AMERICAN JOURNAL OF INDUSTRIAL MEDICINE 58:353–377 (2015)
Review
Epidemiology of Work-related Traumatic Brain Injury: A Systematic Review Vicky C. Chang, MPH,1 E. Niki Guerriero, Bsc (Hon),2 and Angela Colantonio, PhD1,3,4
Objective This systematic review aimed to describe the burden and risk factors of workrelated traumatic brain injury (wrTBI) and evaluate methodological quality of existing literature on wrTBI. Methods A search of electronic databases (MEDLINE, EMBASE, PsycINFO, and CINAHL) was conducted to identify articles published between 1980 and 2013 using a combination of terms for work, TBI, and epidemiology, without geographical limitations. Results Ninety-eight studies were included in this review, of which 24 specifically focused on wrTBI. In general, male workers, those in the youngest and oldest age groups, and those working in the primary (e.g., agriculture, forestry, mining) or construction industries were more likely to sustain wrTBI, with falls being the most common mechanism of injury. Conclusions This review identified workers at highest risk of wrTBI, with implications for prevention efforts. Future research of better methodological quality is needed to provide a more complete picture of the epidemiology of wrTBI. Am. J. Ind. Med. 58:353–377, 2015. ß 2015 Wiley Periodicals, Inc.
KEY WORDS: work-related; traumatic brain injury; epidemiology; systematic review; occupational health and safety
INTRODUCTION Traumatic brain injury (TBI) is a critical public health issue and a major cause of death and disability worldwide.
1
Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada Graduate Department of Rehabilitation Sciences, University of Toronto, Ontario, Canada 3 Department of Occupational Science and Occupational Therapy, University of Toronto, Ontario, Canada 4 Toronto Rehabilitation Institute, University Health Network, Toronto, Ontario, Canada Contract grant sponsor: Canadian Institutes of Health Research; Contract grant number: #CGW-126580 Correspondence to: Dr. Angela Colantonio, PhD, Department of Occupational Science and Occupational Therapy, University of Toronto, 160-500 University Avenue, Toronto, Ontario, Canada M5G 1V7. E-mail: [email protected] 2
Accepted 21 November 2014 DOI 10.1002/ajim.22418. Published online in Wiley Online Library (wileyonlinelibrary.com).
ß 2015 Wiley Periodicals, Inc.
Each year, an estimated 10 million people around the globe sustain a TBI leading to fatality or hospitalization [Hyder et al., 2007]. However, the true burden of TBI is likely much higher due to difficulty capturing mild cases not seeking medical care and the absence of injury surveillance systems in many parts of the world [Langlois et al., 2006; Hyder et al., 2007; Roozenbeek et al., 2013]. Instead of a single injury event, TBI has been increasingly recognized as a chronic health condition, as survivors are often faced with long-term or lifelong physical, cognitive, psychosocial and/or emotional impairments [Masel and DeWitt, 2010; Corrigan and Hammond, 2013]. In the US, it is estimated that at least 5.3 million people, or 2% of the population, are living with disabilities associated with TBI [Langlois et al., 2006]. The epidemiology of TBI has been well-documented [Bruns and Hauser, 2003; Tagliaferri et al., 2006; AbelsonMitchell, 2008; Summers et al., 2009; Roozenbeek et al., 2013]. In general, TBI has a higher occurrence in males and is more likely to affect young children, older adolescents and the
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elderly, with the leading causes being falls, motor vehicle collisions (MVC), struck by/against objects, and assaults/ violence. Additionally, TBI may occur in the workplace [Bruns and Hauser, 2003; Abelson-Mitchell, 2008]. According to data from the Bureau of Labor Statistics, the number of nonfatal occupational TBI cases in the US increased from 7,240 in 2009 to 11,830 in 2012 [BLS, 2014]. Similarly, in the Canadian province of Ontario, while the total number of workers’ compensation (WC) claims decreased over the years, the number of lost-time claims for TBI increased steadily from 1,503 (1.7%) in 2004 to 2,125 (3.9%) in 2013 [WSIB, 2014]. Work-related TBI (wrTBI) is considered among the most serious occupational injuries, leading to profound disruption of workers’ lives and significant economic burdens in terms of medical costs and lost wages [Kim et al., 2006; Colantonio et al., 2010]. Even workers sustaining mild TBI may experience longterm consequences, including challenges in daily activities and return to work [Chang et al., 2011]. Furthermore, it has been shown that wrTBI is significantly different from TBI that did not occur at work (non-wrTBI) in a number of demographic and injury characteristics [Kim et al., 2006]. This emphasizes the importance of identifying wrTBI-specific risk factors in order to inform targeted prevention strategies in work settings. However, while there is a wealth of literature, including reviews, on the epidemiology of TBI among professional athletes [Thurman et al., 1998; Pellman et al., 2004; Benson et al., 2011; Sahler and Greenwald, 2012] and military personnel [Ommaya et al., 1996; Okie, 2005; Warden, 2006; Cameron et al., 2012; Xydakis et al., 2012], research focusing on TBI among the general civilian workforce has been surprisingly sparse until recent years. Moreover, to date, there has not been a comprehensive review of the epidemiological literature on wrTBI, as previous narrative reviews focused primarily on treatment and outcomes from a clinical perspective [Daughton, 1990; Chang et al., 2011]. Given the devastating impacts of wrTBI on the workforce and the need to better understand its etiology for prevention purposes, we conducted a systematic review of the epidemiology of wrTBI. Specifically, this review aimed to describe the burden and demographic, occupational and injury characteristics of wrTBI based on a thorough synthesis of the literature, and critically appraise the quality of existing studies on wrTBI.
METHODS Literature Search Electronic databases MEDLINE, EMBASE, PsycINFO, and CINAHL were searched for the period 1980–2013 to identify English-language studies examining the epidemiology of wrTBI, with no restrictions on geographic location. A combination of search terms and subject headings relating to work, TBI, and epidemiology was used. Search terms for TBI
were selected with reference to a previously published systematic review protocol [Chan et al., 2013]. Search strategies used for each database are presented in Online Supplementary File I.
Inclusion and Exclusion Criteria Studies met inclusion criteria if they (1) provided quantitative information on the burden and/or risk factors (e.g., sex, age, industry, mechanism of injury) of wrTBI; (2) were primary research articles; (3) were published between January 1980 and December 2013; (4) were published in English; and (5) could be retrieved in fulltext. The date range was chosen to exclude older studies that may not reflect current working conditions. We excluded reviews; commentaries; case reports; conference abstracts; government reports with no methods reported; studies focusing on TBI among athletes or military personnel; and studies reporting treatment and/or clinical outcomes with no information on wrTBI risk factors. Studies were also excluded if TBI was not examined separately from neck, spinal cord, facial, and/or superficial head injuries (e.g., cuts and bruises).
Screening Process First, the title and abstract of all studies identified from the search were screened for potential inclusion by two authors (V.C.C. and E.N.G.) independently. Second, the full-texts of potentially eligible studies were retrieved and assessed for meeting inclusion criteria. Reference lists of included studies and relevant review articles were manually searched for additional studies that also met inclusion criteria. Any disagreement between authors was resolved through discussion and consensus or the help of a third author (A.C.).
Data Extraction The following information was extracted from studies that focused on the wrTBI population: study location/period, study type/design/methods, study population, sample size, data source, case definition/severity, and major epidemiologic findings including incidence/mortality, demographic characteristics, industry/occupation, and mechanism of injury. From studies where wrTBI was only a subset of the study population, the percentage of wrTBI was extracted or calculated.
Quality Assessment An assessment of study quality was performed on studies that focused on the wrTBI population, as data from these studies will be the main focus of the review. To assess quality, a 17-item checklist (Online Supplementary File II)
Work-Related Traumatic Brain Injury
was created by modifying items taken from two previously developed tools: one for primary research articles in general [Kmet et al., 2004] and the other specific to studies on occupational injuries/illnesses [Breslin et al., 2005]. Our checklist was designed to evaluate both the quality of reporting and study methodologies in the context of wrTBI. The main methodological considerations evaluated by the checklist included data source and method of subject selection; case definition (i.e., how “work”, “TBI”, and “fatality” were defined); measurement of burden (e.g., rates) and/or risk factors; and statistical analysis. A score of 0, 1, 2, or “N/A” (not applicable) was assigned to each item. Due to differences in the maximum possible score, both a fraction (out of 34 or less) and a percentage were calculated for each study for ease of comparison. Quality assessment was performed by two authors (V.C.C. and E.N.G.) independently, and disagreements were resolved by discussion until consensus was reached.
RESULTS The literature search yielded 8,063 records. After duplicates were removed, titles and abstracts of 6,266 articles were screened and 237 full-text articles were assessed for eligibility. Fifty-seven of these studies met the inclusion criteria and an additional 41 were identified from reference lists, totaling 98 studies included in this review. Of these studies, 24 focused specifically on wrTBI; 33 on work-related injuries, including a subset of TBI; 40 on all cases of TBI, including a subset that were work-related; and one on injuries in general, including estimates of wrTBI. A diagram detailing the search results is presented in Figure 1. Table I provides a summary of the 24 studies focusing on wrTBI, including results from the quality assessment. Of these studies, three (12.5%) were restricted to fatal cases; 12 (50%) included both fatal and nonfatal cases; and nine (37.5%) examined nonfatal cases only. Geographically, 11 (46%) studies were conducted in the US, 10 (42%) in Canada, and one (4%) in each of Great Britain, Hong Kong, and the United Arab Emirates. Moreover, two (8%) studies were published before 1990; six (25%) from 1990–1999; five (21%) from 2000–2009; and 11 (46%) in 2010 or later. Unless otherwise specified, the following sections pertain to findings from the 24 studies that focused on wrTBI only.
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sectional design, seven (29%) were case series, and one (4%) used a historical cohort design. Additionally, 13 (54%) studies involved retrospective analysis of existing data, while 11 (46%) studies relied on chart reviews. Three studies that focused on wrTBI deaths used data from government inspection records [Janicak, 1998], coroners’ files [Tricco et al., 2006], or an occupational injury fatality database containing information from multiple sources [Tiesman et al., 2011]. The majority of the remaining studies (15 of 21; 71%) used data derived from WC claims, which may include medical billing records in addition to other administrative files. Hospitalbased data (e.g., trauma registries and medical records) were another commonly used data source, either alone or in combination with WC claims. TBI cases were defined using standard coding systems, such as the International Classification of Diseases (ICD) and/or WC-based codes, in 16 (67%) of the 24 studies. However, even when the same coding system was used, specific codes varied across studies. The remaining eight studies defined TBI using clinical diagnostic criteria without mention of codes or did not provide a clear definition of TBI.
Quality Assessment Quality assessment scores of the 24 wrTBI studies ranged from 53% to 94%: four studies scored below 70%, seven scored between 70% and 79%, nine scored between 80% and 89%, and four scored above 90%. Some of the most common methodological limitations were: insufficient description of the data source; biased/unrepresentative sample of the population of interest; low population coverage of the data source (e.g., 12 Mean ISS: wrTBI: 26.1 non-wrTBI: 27.1
Clinical or imaging evidence of WC claims (Washington brain injury, diagnosis of State Fund system), with concussion, or loss/alteration hospital billing records of consciousness; excluding closed head injury/fracture with none of the above; defined using diagnosisrelated group (DRG) codes or ICD-9 þ American National Standards Institute Z16.2 codes
Descriptive; cross-sectional Workers with wrTBI, (with incidence rate hospitalized within one calculated for each week of injury n ¼ 301 year); retrospective analysis of existing data
ICD-9-CM codes 800.0^801.9, 803.0^804.9, 850.0^854.1, 950.1^950.3, or 959.01 ISS: 0^8: 16% 9^15: 30% 16^24: 28% 25^75: 26%
Heyer and Franklin [1994] Washington State, US; 1988^1990
Data source
TBI case definition/severity measures
Trauma registry (WashingtonTrauma Registry) linked to WC claims (Washington State Fund) *All cases were identified from trauma registry data, and 71% were linked to WC data
Study population/sample size
Descriptive; cross-sectional; Adolescent and young adult retrospective analysis of workers (aged 16^24 existing data years) who sustained fatal (dead on arrival or in-hospital death) or nonfatal wrTBI involving inpatient admission of 48 hr, trauma resuscitation team activation, and/or interfacility transfer by emergency medical services n ¼ 273 (6% fatal)
Study type/design/ methods
Graves et al. [2013] Washington State, US; 1998^2008
Author [year]; Location/period
TABLE I. (Continued.)
^
9.4 per 100,000 FTE per year Decreasing trend overall
^
Incidence/mortality
Score: 28/34 (82%) Province-wide trauma registry data Large sample of TBI cases, with comparisons made between wrTBI and nonwrTBI cases Work-relatedness not defined Unclear source of denominators used for rate calculations (used male workers in Ontario, although study included both males and females)
wrTBI (n ¼ 950) Fall: 45% MVC: 21% Struck by/against: 16% Machinery: 9% Other: 9% 4% intentional (assault by firearms: 31%; fight or brawl: 25%; assault by other means: 25%) non-wrTBI (n ¼12,041) MVC: 68% Falls: 19% Struck by/against: 8% Other: 5% 11% intentional (fight or brawl: 36%; assault by other means: 27%; suicidal jump: 10%) wrTBI only (n ¼ 950) Construction: 37% Transportation: 15% Primary industry: 13% Manufacturing: 13% Sales/services: 10% Recreation/sports: 0.7% Medicine/Health: 0.5% Rate per 100,000 workers Primary industry: 9.4 Construction: 5.5 Manufacturing: 3.0 Transportation: 2.0 Sales/services: 1.5 Medicine/health: 0.8 Recreation/sports: 0.8 wrTBI (n ¼ 950) Sex: M: 94%; F: 6% Mean age: 38.9 Age groups 16^24: 13% 25^34: 23% 35^44: 27% 45^54: 23% 55^64: 14% non-wrTBI (n ¼12,041) Sex: M: 72%; F: 28% Mean age: 35.6 Age groups 16^24: 29% 25^34: 23% 35^44: 20% 45^54: 16% 55^64: 13%
(Continued )
Score: 28/32 (88%) WC system covered two thirds of workers in the state Explored the use of different combinations of codes forTBI case finding and checked a sample of original records Used length of stay as a proxy for injury severity No mention of fatal cases Fall: 49% (40% from elevation þ 9% on same level) Struck by/against: 30% (26% by þ 4% against) Highway MVC: 18% Caught in/under/between: 2% Highway, non MVC: 1% Explosion: 1%
Score: 32/34 (94%) Linkage of two populationbased data sources, capturing 85% of trauma victims Demonstrates undercover age of young workers by the WC system Potential misclassification of work-related injuries in trauma registry data
Quality assessment (score/ comments)
Selected industry-specific rates per 100,000 FTE per year Logging: 345.2 Roof work: 160.6 Garbage collecting: 127.2 Street and road construction: 116.6 Trucking: 94.4 Farms (dairy): 83.4 Interior finished carpentry: 82.8 Building construction: 68.1
Fall: 42% MVC: 23% Struck by/against: 16% Machinery: 3% Other: 16%
Mechanism of injury
Sex-specific rates per 100,000 FTE per year: M: 15.1; F: 2.4 Mean age: 36 (range: 14^75) Rates peaked in the 15^34 and 56^64 age groups
^
and 8 of Coleman, 1986.
Industry/occupation
Main findings
Sex: M: 87%; F: 13% Age groups 16^18: 15% 19^21: 37% 22^24: 48% Race/ethnicity White: 65% Latino /Hispanic: 19% Other: 4% Missing: 12%
Demographic characteristics
Work-Related Traumatic Brain Injury 359
Descriptive; cross-sectional Workers aged 16 who validation study; sustained fatal (dead on retrospective analysis of arrival or in-hospital death) or nonfatal wrTBI existing data involving inpatient admission of 48 hr, trauma resuscitation team activation, and/or interfacility transfer by emergency medical services, and had >3 days lost from work n ¼1,313 (9% fatal)
Sears et al. [2013] Washington State, US; 1998^2008
TBI cases admitted to a hospital, excluding deaths on arrival and deaths from other causes All TBI: n ¼ 581 wrTBI: n ¼ 56 (8% fatal)
Descriptive; case series; retrospective chart review
Salem et al. [2013] Abu Dhabi, United Arab Emirates; 2005^2009
Trauma registry (WashingtonTrauma Registry) linked to WC claims (Washington State Fund) *only included cases with both both data available
Different combinations of OIICS nature of injury (06, 086, 012, 08, 4, 9999), and part of body (01, 00/01/08, 0, 8) codes, compared to ICD-9-CM codes (800.0^801.9, 803.0^804.9, 850.0^854.1, 950.1^950.3, or 959.01)as the gold standard
ICD-9 codes based on CDC case definition of TBI GCS mild: 70% moderate: 9% Severe: 21%
Skull fracture (ICD-9 800^804), intracranial injury (ICD-9 850^ 854), or other injury with residual brain damage (e.g. anoxia due to electric shock or heat stroke) 60% had 2 days of unconsciousness
Selected subset of WC cases WC claim files from an involving TBI insurance carrier, postn ¼ 86 TBI survey questionnaire
Descriptive; case series; retrospective chart review and crosssectional survey
Medical records
Physical damage to, or functional impairment of, the cranial contents from acute mechanical energy exchange GCS: Mild: 79% Moderate: 11% Severe: 3%
Data source
TBI case definition/severity measures
Countywide emergency room/hospital admission records; coroners records, death certificates, nursing home and care facility records
Study population/sample size
Descriptive; cross-sectional; Fatal and nonfatal TBI cases retrospective chart among civilian and review military personnel aged 16 years, with a focus on male wrTBI cases All TBI: n ¼ 3,358 wrTBI: n ¼114(males: n ¼107, 7% fatal)
Study type/design/ methods
Mittelmann et al. [1991] Hartford, Connecticut, US; 1982^1989
Kraus and Fife [1985] San Diego County, California, US; 1981
Author [year]; Location/period
TABLE I. (Continued.)
^
^
^
19.8 per 100,000 male workers (9.9 per 100 million work hours)
Incidence/mortality
^
Sex: M: 100%; F: 0% Age groups 45: 11% Nationality Bangladeshi: 39% Indian: 20% Pakistani: 19% Egyptian: 15% Syrian: 6%
Sex: M: 94%; F: 6% Mean age: 36 (range: 15^70)
^
All cases, identified by ICD codes(n ¼1,313) Fall: 50% MVC: 20% Struck by/against: 15% Machinery: 4% Other: 11% Identified by the most sensitive OIICS-based definition (n ¼ 505) Fall: 47% Struck by/against: 24% MVC: 11% Machinery: 7% Other: 11%
Fall: 63% (80% from3m height) Struck by falling/moving object: 34% MVC: 4% By severity Mild: 51% fall; 44% struck; 5% MVC Moderate: 80% fall; 20% struck Severe: 92% fall; 8% struck
^
(Continued )
Score: 30/32 (94%) Linkage of two populationbased data sources Explored OIICS-based TBI case definitions Limited to severe cases with both trauma registry and WC data available Demonstrates undercount of wrTBI by WC data
Score: 22/30 (73%) Case series from a single hospital (limited generalizability) Work-relatedness not defined Mechanisms of injury stratified by injury severity
Score: 17/30 (57%) Biased and unrepresentative sample of wrTBI No information on how cases were selected for inclusion Use of non-TBI codes
Score: 29/34 (85%) Comprehensive coverage of records from different data sources (e.g., 95% of hospital beds) Not clear if standard codes were used to define TBI cases Work-relatedness not defined for civilian workers Females excluded
Civilian (n ¼ 65) Fall: 54% Struck by/against: 32% On-road MVC: 8% Firearms /assaults: 5% Off-road MVC: 2% Military (n ¼ 42) Off-road MVC: 36% On-road MVC: 21% Fall: 21% Struck by/against: 14% Firearms /assaults: 7% Fall: 41% Struck by object: 28% MVC: 19% Gunshot: 2% Other: 10%
Quality assessment (score/ comments)
Mechanism of injury
^
Civilian: 61% Military: 39% Rate per 100,000 male workers Civilian: 15.2 Military: 37.0 Rate per 100 million work hours Civilian:7.6 Military:18.5
Industry/occupation
Main findings
Sex: M: 94%; F: 6% Only males were included for further analysis (n ¼107) Rates decreased with increasing age for both civilian and military personnel
Demographic characteristics
360 Chang et al.
Colantonio and Comper [2012] Ontario, Canada; 1998^2001
Nonfatal only Colantonio et al.[2009] Ontario, Canada; 2004^2005
Descriptive; case series; retrospective chart review
Medical records and WC Workers with wrTBI, aged claim files (Ontario >15 years at time of WSIB) injury, have not returned to work 6 weeks postinjury, discharged from a WSIB-referred outpatient neurology service between 1998 and 2001 n ¼ 435
Descriptive; cross-sectional; Construction workers who WC claims (Ontario WSIB, retrospective analysis of sustained nonfatal wrTBI abstracted by the existing data resulting in days off Construction Safety work Association of Ontario) n ¼ 218 Sex: not reported Mean age: 35.8 Median age: 34 Age groups 17^24: 23% 25^34: 28% 35^44: 22% 45^54: 17% 55^64: 10%
Sex: M: 75%; F: 25% Age groups 44: 31% >44: 69% Married: 70% Less than high school education: 47%
^
Injury of appreciable magnitude to the head Most classified as ‘‘mild’’ Loss of consciousness: 52% (mostly 15 years at time of WSIB) injury, have not returned to work 6 weeks postinjury, discharged from a WSIB-referred outpatient neurology service between 1998 and 2011,with a focus on wrTBI due to falls Total wrTBI: n ¼ 435 Falls only: n ¼ 214
Head injury Most classified as ‘‘mild’’
TBI case definition/severity measures
Medical records and WC Workers with wrTBI, claims (Ontario WSIB) presented to the senior author between 1993^ 1997 with dizziness as the major complaint from an otoneurological perspective, referred by the WSIB, with 6 months follow-up from time of injury to date of initial neurotological assessment n ¼ 365
Medical records and WC Workers with wrTBI, aged claim files (Ontario >15 years at time of WSIB) injury, have not returned to work 6 weeks postinjury, discharged from a referral-based outpatient neurology service between 1998 and 2011,with a focus on construction workers Total: n ¼ 435 Construction: n ¼ 83
Study population/sample size
^
^
^
Incidence/mortality
Industry/occupation
Main findings
^
All falls (n ¼ 214) Occupations Trades/transport: 37% Professional/manager/ skilled: 34% Manufacturing: 17% General laborer: 13% Industries Construction: 25% Manufacturing: 19% Retail/wholesale: 14% Government/related services: 12% Transport/storage: 10% Primary industry/ mining: 5% Other: 15%
Sex: M: 83%; F: 17% Mean age at assessment: 45 (range: 18^71)
All falls (n ¼ 214) Sex: M: 71%; F: 29% Aged 45: 76% Did not complete secondary school: 47% Same level (n ¼115) Sex: M: 54%; F: 46% Aged45: 79% Did not complete secondary school: 39% From elevation (n ¼ 99) Sex: M: 90%; F: 10% Aged45: 73% Did not complete secondary school: 57%
Construction (19%) Construction (n ¼ 83) Trades/transport/ Aged45: 66% equipment operator: Married: 68% 55% Did not complete General laborer: 41% secondary school: 64% Other (81%) Speaks English or Trades/transport/ French: 65% equipment operator: Immigrant: 47% 35% Other (n ¼ 352) General laborer: 5% Aged45: 69% Other: 60% Married: 71% Did not complete secondary school: 43% Speak English or French: 70% Immigrant: 50%
Demographic characteristics
Fall: 49% of all wrTBI Same level: 54% From elevation: 46% Agent in contact with head: Working area: 80% Unboxed material: 12% Human/vehicle: 4% Tools/machinery: 2%
Fall: 47% Struck by/against: 35% MVC: 12% Assault: 4% Explosion: 2%
Construction (n ¼ 83) Fall: 66% (59% from elevation þ 7% on same level) Struck by object: 36% Struck against object/ building: 11%/8% MVC: 6% Other (n ¼ 352) Fall: 46% (15% from elevation þ 31% on same level) Struck by object: 36% Struck against object/ building: 13%/12% MVC: 13%
Mechanism of injury
(Continued )
Score: 21/28 (75%) Generalizable only to WSIB insured cases with persistent symptoms and those who have not returned to work Lacked a clear definition of TBI and injury severity Validated tool used for data abstraction Comparisons of wrTBI cases by type of fall
Score: 20/28 (71%) Convenience sample with very specific inclusion criteria ^ not generalizable to all wrTBI cases No clear definition of TBI (i.e., no codes used) although severity grades were assigned based on type of TBI Data source not sufficiently described
Score: 23/28 (82%) Generalizable only to WSIB insured cases with persistent symptoms and those who have not returned to work Lacked a clear definition of TBI and injury severity Validated tool used for data abstraction Comparisons made between wrTBI cases in construction vs. other industries
Quality assessment (score/ comments)
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TBI, traumatic brain injury; wrTBI, work-related TBI; WC, workers’compensation; WSIB,Workplace Safety and Insurance Board; OIICS, Occupational Injury and Illness Classification System; ICD, International Classification of Diseases; ICD-9-CM, ICD, 9th revision, Clinical Modification; ISS, Injury Severity Score; GCS, Glasgow Coma Scale; CDC, Centers for Disease Control and Prevention; FTE, full-time equivalent; M, male; F, female; MVC, motor vehicle collision. Note that some information may be missing (i.e., not reported or not applicable) from each study.
Fall: 46% MVC: 29% Struck by object: 14% Assault: 5% Machinery: 3% ^ Sex: M: 76%; F: 24% Age groups 18^24: 13% 25^34: 16% 35^44: 22% 45^54: 18% 55^64: 14% 65: 17% 6.2 per 100,000 workers per year Decreasing trend overall ICD-9-CM codes established in Minnesota Rules, including codes used by the CDC and other codes associated with TBI
Incidence/mortality Data source
Descriptive; cross-sectional; Nonfatal hospital-admitted TBI registry (MinnesotaTBI Registry) retrospective analysis of cases of wrTBI, aged existing data 18 years and injured while working for income n ¼1,722 Wei et al. [2012] Minnesota, US; 1999^2008
Mechanism of injury Industry/occupation
Main findings
Demographic characteristics TBI case definition/severity measures Study population/sample size Study type/design/ methods Author [year]; Location/period
TABLE I. (Continued.)
Score: 26/32 (81%) Population-based TBI registry TBI codes used were not clearly stated Potential misclassification of work-related injuries in medical records Rates not calculated by subgroups (e.g., sex, age)
Chang et al. Quality assessment (score/ comments)
364
database of occupational fatalities between 2003 and 2008, the mortality rate of wrTBI was estimated at 0.8 per 100,000 workers per year [Tiesman et al., 2011]. In an Ontario study using coroners’ records of wrTBI fatalities, a rate of 6.45 per 100,000 male workers was reported over a 5-year period 1996–2000 [Tricco et al., 2006]. This averaged to 1.3 per 100,000 per year, which is similar to the malespecific mortality rate (1.5 per 100,000 per year) reported in the US [Tiesman et al., 2011].
Severity and case fatality Seven studies presented data on the severity of wrTBI cases, assessed using measures such as the Glasgow Coma Scale (GCS), Injury Severity Score (ISS), and duration of loss of consciousness and/or post-traumatic amnesia. Specifically, two studies using hospital records showed that the majority (>70%) of hospitalized wrTBI cases were mild (i.e., GCS 13–15) [Kraus and Fife, 1985; Salem et al., 2013], while studies using trauma registry data had more severe cases as defined by the ISS [Kim et al., 2006; Graves et al., 2013]. In nine studies, the percentage of fatal cases (i.e., case fatality rates) ranged from 4% to 11%.
Demographic characteristics Across all studies presenting data on sex distribution, males comprised a greater proportion of wrTBI cases than females. However, relative proportions varied according to the degree of injury severity. In the only study examining sex distribution of wrTBI fatalities, 93% of cases were males [Tiesman et al., 2011]. Similarly, in seven studies examining hospitalized/fatal wrTBI, males accounted for 87–100% of cases. When restricted to nonfatal cases, the proportion of males ranged from 64% to 83% across seven studies, with the lowest percentages (80%) involved falls from an elevation [Heyer and Franklin, 1994; Cohen et al., 1999; Wrona, 2006; Salem et al., 2013], while falls from the same level were more common among nonfatal and less severe cases [Colantonio et al., 2010; Wei et al., 2010; Liu et al., 2011]. MVC and being struck by/against were also among the top three causes of wrTBI. In general, MVC were more common among fatal and/or severe cases compared to being struck/by against [Kim et al., 2006; Wrona, 2006; Tiesman et al., 2011; Graves et al., 2013; Sears et al., 2013]. Unlike falls, MVC were more common among younger workers [Kim et al., 2006; Wei et al., 2012] and were the leading cause of fatal wrTBI in workers below 55 years of age and in the transportation/warehousing industry [Tiesman et al., 2011]. Being struck by/against was the leading cause of wrTBI when a wider range of severity levels were examined [Colantonio et al., 2010]. It also occurred more frequently among younger workers [Mittelmann et al., 1991; Kim et al., 2006; Colantonio et al., 2009, 2010; Tiesman et al., 2011] and was the leading cause of severe and/or fatal wrTBI in the primary industries [Kim et al., 2006; Tiesman et al., 2011]. Other notable mechanisms of injury included assaults/ violence, machinery incidents, and being caught/crushed. In particular, assaults accounted for 2–5% of wrTBI cases according to six studies [Kraus and Fife, 1985; Mittelmann et al., 1991; Ogawa and Rutka, 1999; Kim et al., 2006; Wrona, 2006; Wei et al., 2012], and 10–20% of wrTBI fatalities according to two studies [Wrona, 2006; Tiesman et al., 2011]. Specifically, Tiesman et al. [2011] found that more than 40% of wrTBI deaths among women were caused by assaults or violent acts, including self-inflicted injuries.
1982^1986 1990^1992 1980^1985
Washington State, US
New York State, US Massachusetts, US Washington State, US Greece
Washington State, US
Washington, DC, US Washington and Alaska, US
Sears et al. [2011]
Belville et al. [1993] Brooks and Davis [1996] Miller and Kaufman [1998] Alexe et al. [2003]
Demers and Rosenstock [1991] Hunting et al. [1994] Holman et al. [1987]
1980^1987 1987^1990 1988^1991 1996^2000
1998^2008
2009 Feb^ Aug
Taiwan
Lin et al. [2012]
2002^2006
US
Konstantinidis et al. [2011]
1989 Jan^ Feb
1980^1989 1990^1999 1990^2001 1991^1994 1991^1994 1992^2000
Aberdeen, UK
Dunn and Runyan [1993] Etiler et al. [2004] Colak et al. [2004] Jeong [1998] Jeong [1997] Scott [2004]
2003^2008 1996^2000
1997^2003
North Carolina, US Kocaeli,Turkey Kocaeli,Turkey South Korea South Korea US
Tiesman et al. [2011] Tricco et al. [2006]
1986^1989
1994^1996 1998^2008
1979^1983
1978
Study period
Illinois, US
US Ontario, Canada
Shannon et al. [1993]
Fatal/nonfatal Friedman and Forst [2008] Harker et al. [1991]
Ontario, Canada
Janicak [1998] Sears et al. [2013]
Maryland, US
Location
Metro Dade County, Florida, US US Washington State, US
Copeland [1985]
Fatal only Baker et al. [1982]
Author [year]
TABLE II. Proportion of Work-Related Injuries Identified asTBI
592 51
25,097
9,656 2,551 15,051 2,367
9,185
4,403
67,658
578
17,422
71 387 153 3,028 2,533 780
33,641 488
470
3,202 NR
147
148
Sample sizea
Construction workers Loggers
Agricultural workers
Adolescent workers (14^17 y) Adolescent workers (14^17 y) Adolescent workers (11^17 y) Farm workers
Workers
Workers
Workers
Workers
Workers
Adolescent workers (900 centers)
Statewide trauma registry
Medical examiners’ records Occupational injury registry records Occupational injury registry records National industrial accident statistics National industrial accident statistics Census of Fatal Occupational Injuries
Coroners’ records and Ministry of Labor fatality inspection records Census of Fatal Occupational Injuries Coroners’ records
Occupational fatality inspection records Trauma registry linked to WC claims data
Medical examiners’ records, WC claims, occupational agency reports, vital records Medical examiners’ records
Data source
2% 43%
0.4%
0.6% 0.5% 0.7% 3%
21%
11%
16%
0.3%
9%
34% 24% 26% 19% 12% 43%
22% 45%
6%
27% 60%
25%
21%
% TBI
(Continued )
Head injury/concussion (ICD-9 codes) Head injury (skull fractures, concussions, major
Concussion
TBI (ICD-9-CM 800.0^801.9, 803.0^804.9, 850.0^854.1, 950.1^950.3, 959.01) Concussion Concussion (ANSI codes) Concussion (ANSI codes) Concussion
TBI, including concussion, fractured skull, intracranial hemorrhages, and other head injury Intracranial injury
Concussion
TBI involving internal injury (ICD-9 N codes)
Death due to head injury Death involvingTBI (ICD-9-CM 800.0^801.9, 803.0^804.9, 850.0^854.1, 950.1^950.3, 959.01) Intracranial injury (ICD-9 N codes), as either the first or second injury specified TBI accounting for death (OIICS codes) Injuries included TBI (ICD-9 N800^804, 850^ 854) Blunt head trauma as mechanism of injury Head trauma as cause of death Head trauma as cause of death Concussion as nature of injury Cerebral concussion as nature of injury Head as part of body injured which led to death
Craniocerebral trauma as cause of death
Head injury as the only severe injury causing death
TBI case definition
366 Chang et al.
Massachusetts, US South Korea South Korea Umea , Sweden
North Carolina, US St. Louis, Missouri, US Australia Australia
Brooks et al. [1993] Jeong [1998] Jeong [1997] Bylund and Bj€ornstig [1998]
Kucera et al. [2010] Lipscomb et al. [2003] Lucas et al. [2009b] Lucas et al. [2009a]
1999^2001 1999^2002 1960^ 1960^
1979^1982 1991^1994 1991^1994 1985
1986 2001^2004 1997^1999
1980^1981
1995^2003 2006^2008
1990^1999
Study period
125 117 2,188 453
1,176 125,929 186,726 398
31,588 467 5,546,000
11,586,000
15,113 306
33
Sample sizea
Fishermen Carpenters (falls only) Veterinarians Veterinarians (horse-related injuries only)
Adolescent workers (14^17 y) Construction workers Manufacturing workers Mechanics and construction metal workers
Workers Workers Workers
Workers
Male goods-transport drivers Workers (ladder falls only)
Loggers
Injured worker population
National probability survey (household interview) WC claims Hospital records and questionnaire National probability survey (household interview) ED and hospital admission records National industrial accident statistics National industrial accident statistics Hospital records, occupational agency reports, WC claims Telephone interviews Questionnaire Questionnaire Questionnaire
Occupational hospitalization registry National injury surveillance system (65 ED) and questionnaire
Medical records from 1trauma center
Data source
Concussion Concussion Intracranial injury Intracranial injury
Concussion/cranial injury (ICD-9-CM codes) Concussion Cerebral concussion Concussion
Skull fractures and intracranial injuries (ICD-9 800^804, 850^854) Brain concussion (ANSI codes) Brain trauma Skull/brain as body region injured
brain injuries) Head injury (concussion, skull fractures, subarachnoid hemorrhage) Concussion (ICD-10 S06.0) Concussion
TBI case definition
1% 2% 3% 6%
2% 3% 1% 0.8%
0.6% 6% 3%
3%
1% 3%
48%
% TBI
TBI,traumaticbraininjury;WC,workers’compensation;ED,emergencydepartment;ICD,InternationalClassificationofDiseases;ICD-9-CM,ICD,9threvision,ClinicalModification;OIICS,OccupationalInjuryandIllnessClassification System; ANSI, American National Standards Institute; NR, not reported. a Sample size refers to the denominator (i.e., total number of work-related deaths or injuries) used to determine the percentage of TBI.
Washington State, US Guangzhou, China US
Fulton-Kehoe et al. [2000] Li et al. [2008] Smith et al. [2005]
US
Denmark US
Shibuya et al. [2008] Lombardi et al. [2011]
Nonfatal only Collins [1986]
Pennsylvania, US
Location
Johnson et al. [2002]
Author [year]
TABLE II. (Continued.)
Work-Related Traumatic Brain Injury 367
Al-Ain city, United Arab Emirates
Virginia, US Olmsted County, Minnesota, US
St Gallen, Switzerland
Sfax,Tunisia Veneto Region, Italy
Toronto, Ontario, Canada
NorthwesternTanzania
Hualien County, Taiwan
Ontario, Canada
New South Wales, Australia
Trndelag, Norway
Sydney, Australia King County, Washington, US
US
Ontario, Canada
San Diego County, California, US
Alberico et al. [1987] Annegers et al. [1980]
Annoni et al. [1992]
Bahloul et al. [2004] Baldo et al. [2003]
Cadotte et al. [2011]
Chalya et al. [2011]
Chiu et al. [1995]
CIHI [2004]
Dan et al. [1986]
Edna and Cappelen [1984]
Fearnside et al. [1993] Gale et al. [1983]
Jager et al. [2000]
Kim et al. [2006]
Kraus and Fife [1985]
Dharan, Nepal
Fatal/nonfatal Agrawal et al. [2009]
Location
Al-Kuwaiti et al. [2012]
Tabriz, Iran
Fatal only Bavil [2008]
Author [year]
1981
1993^2001
1992^1994
NR 1980^1981
1979^1980
1977^1978
2001^2002
1988^1991
2008^2010
1986^2007
1997^1999 1996^2000
1987
1976^1984 1935^1974
2003^2006
2005
1999^2004
Study period
TABLE III. Proportion of Traumatic Brain Injuries Identified as Work-Related
3,358
12,991
1,144,807
315 451
1,124
126
2,489
5,378
260
9,315
437 32,919
80
230 3,587
589
334
216
Sample sizea
Trauma registry (single center) Questionnaire from a hospital ED Admission records from 4 major hospitals, medical examiners’ reports, death certificates Provincial trauma registry (lead trauma hospitals) Statewide hospital records and death certificates Population-based hospital admission records
Medical records from 1hospital ED/hospital records from a regional trauma center National probability survey of ED visits
14 0 8 0 0
0 0
0
16^64
0
0
0
Provincial trauma registry (lead trauma hospitals) Population-based ED/hospital records, coroners’ records, death certificates,
Medical records from regional neurosurgical units Medical records from a hospital ICU Population-based hospital records
0
0
Medical records from 1hospital Countywide medical records linkage system, including death certificates and autopsy reports
Trauma registry (single center)
0
20^80 0
Medical records from a surgery department
Autopsy reports from 1hospital
Data source
0
0
Age (year)
3%
7%
4%
1% 4%
5%
3%
4%
12%
0.4%
5%
4% 9%
10%
2% 4%
14%
0.6%
6%
% WR
(Continued )
ICD-9-CM 800.0^801.9, 803.0^804.9, 850.0^ 854.1 ICD-9-CM 800.0^801.9, 803.0^804.9, 850.0^ 854.1; ISS >12 Physical damage to, or functional impairment of, the cranial contents from acute
ICD-N 800, 801, 803, 804, 850, 851, 852, 853, 854; ISS >12 Extradural hematoma occurring alone, with no other hematoma Physical injury to the brain or skull caused by external force, with LOC, skull fracture, or development of intracranial hematoma SevereTBI (GCS 8) Mild/moderate/severeTBI (based on GCS)
Mild/moderate/severeTBI (defined by period of LOC and PTA) Head injury (concussion, fractured skull, subdural/epidural hematoma, subarachnoid bleeding, intracerebral hemorrhage, brain contusion) SevereTBI (GCS 7) Head injury with evidence of presumed brain involvement: concussion with LOC, PTA, or neurological signs of brain injury; skull fracture Intracranial lesions shown on admission CT scan Mild/moderate/severeTBI (based on GCS) ICD-9-CM 800.0^801.9, 803.0^804.9, 850.0^ 854.1 ISS >12 and Head Abbreviated Injury Scale (HAIS) score >0 Blunt or penetrating injury affecting the cranium and its contents ICD-9 800, 801, 803, 804, 850, 851, 852, 853, 854
Death due to severe head injury before or after admission
TBI case definition/severity
368 Chang et al.
Hanover and M€unster, Germany
New South Wales, Australia
Austria Abu Dhabi, United Arab Emirates US
Romagna and Trentino, Italy
New South Wales, Australia
New South Wales, Australia
New South Wales, Australia
Autonomous Region of Cantabria, Spain
Oulu and Lapland, Finland
Toronto, Ontario, Canada
Hong Kong Calgary Health Region, Alberta, Canada
Rickels et al. [2010]
Ring et al. [1986]
Rosso et al. [2007] Salem et al. [2013] Schootman and Fuortes [2000]
Servadei et al. [2002]
Stening et al. [1986a]
Stening et al. [1986b]
Vanderfield et al. [1986]
Va´zquez-Barquero et al. [1992]
Winqvist et al. [2008]
Wong et al. [1993]
Yue et al. [1983] Zygun et al. [2005]
New Zealand
12 European countries Australia and New Zealand Kingston, Ontario, Canada
Murray et al. [1999] Myburgh et al. [2008] Pickett et al. [2001]
Nonfatal only Alexander et al. [2007]
Taiwan
Location
Lee et al. [1990]
Author [year]
TABLE III. (Continued.)
2003^2004
1970^1981 1999^2002
1978^1991
1978^2000
1988
1977^1978
1977^1978
1977^1978
1998
2001^2003 2005^2009 1995^1997
1977^1978
2000^2001
1995 Feb^ Apr NR 1998
1977^1987
Study period
161
60 241
456
236
477
135
290
129
R: 2,880 T: 1,562
391 581 1,400,000
991
6,783
996 635 202
10,000
Sample sizea
Statewide hospital records and death certificates Hospital admission records from 5 hospitals Admission records from 1hospital National probability survey of ambulatory care (ED, outpatient, physicians’ office) visits Population-based hospital admission records
0
NR
0 18
18
12
0
0
0
0
0
Medical records from a concussion clinic
Hospital records from a general surgical unit Population-based records from a tertiary care trauma center and all acute care facilities
Population-based hospital discharge registry, hospital records, questionnaire (birth cohort) Medical records from 1hospital
Statewide hospital records and death certificates Statewide hospital records and death certificates Statewide hospital records and death certificates Population-based hospital admission records
Population-based hospital ED records
0
0 NR 0
Survey completed by 67 neurosurgical centers Case reports from ICU of major trauma centers Population-based surveillance program, ED and inpatient care records from all hospitals
nursing home records Admission records from a major hospital
Data source
>16 >16 0
0
Age (year)
External force to the head, mild/moderate/ severeTBI
7%
15% 6%
0.7%
3%
8%
3%
2%
6%
R: 8% T: 2%
7% 10% 7%
3%
15%
6% 1% 3%
3%
% WR
(Continued )
Acute/subacute subdural hematoma occurring alone, with no other hematoma Chronic subdural hematoma occurring alone, with no other hematoma Head injury with LOC, skull fracture, or objective neurologic findings ICD-8 and ICD-9 N codes 800, 801, 803, 850, 851^854; or ICD-10 S02.0^ S02.11, S06.0^ S06.9, S07.1 Medical diagnosis of TBI with potential for rehabilitation Extradural hematoma SevereTBI (GCS 8, requiring intracranial pressure monitoring, or presence of clinical/radiographic herniation) and ISS 12
ICD-9 800.0^800.3, 801.0^801.3, 803.0^ 803.3, 850, 851.0^851.1, 852.0^852.1, 853.0^853.1, 854.0^854.1 Multiple intracranial hematomas
mechanical energy exchange Head injury with LOC, PTA, clinical signs of focal brain lesion, and/or evidence of traumatic intracranial lesions by CTscan Moderate/severeTBI (GCS 12) Mild/moderate/severeTBI (based on GCS) Blunt head trauma resulting in LOC, PTA, or disorientation; skull fracture; intracranial injury; or head injury resulting in hospitalization Acute head injury with clinical symptoms; ICD10 S02, 04, 06, 07, 09 ICD-8 851^3, 800^804, 850, 854; operation codes SevereTBI (GCS 8) ICD-9 codes, based on CDC’s definition of TBI ICD-9-CM 800^801, 803^804, 850^854
TBI case definition/severity
Work-Related Traumatic Brain Injury 369
18
1,255
62
1,381
357
495
NR
1993^1998
1992^1993
2003^2005
2002^2004
1983
1999^2008
US
Staffordshire, UK
Reading, UK
Internet-based, mainly US
Christchurch, New Zealand
6 cities in China
Minnesota, US
Collins [1986]
Haboubi et al. [2001]
Powell et al. [1996]
Setnik and Bazarian [2007]
Snell and Surgenor [2006]
Wang et al. [1986]
Wei et al. [2012]
TBI, traumatic brain injury; WR, work-related; ICU, intensive care unit; ED, emergency department; LOC, loss of consciousness; PTA, post-traumatic amnesia; GCS, Glasgow Coma Scale; CT, computerized tomography; ICD, International Classification of Diseases; ICD-9-CM, ICD, 9th revision, Clinical Modification; ISS, Injury Severity Score; CDC, Centers for Disease Control and Prevention; NR, not reported. a Sample size refers to the denominator (i.e., total number of TBI cases) used to determine the percentage of TBI that were work-related.
0
4% StatewideTBI registry
16
24% Door-to-door survey, medical records
13
6%
Internet-based survey on a patient-oriented website of a medical center Medical records from a concussion clinic
>16
13%
Medical records from 1hospital
16^65
7%
14%
Skull fractures and intracranial injuries (ICD-9 800^804, 850^854) Mild TBI (GCS 13^15), seen in ED or admitted to hospital for
Review
Epidemiology of Work-related Traumatic Brain Injury: A Systematic Review Vicky C. Chang, MPH,1 E. Niki Guerriero, Bsc (Hon),2 and Angela Colantonio, PhD1,3,4
Objective This systematic review aimed to describe the burden and risk factors of workrelated traumatic brain injury (wrTBI) and evaluate methodological quality of existing literature on wrTBI. Methods A search of electronic databases (MEDLINE, EMBASE, PsycINFO, and CINAHL) was conducted to identify articles published between 1980 and 2013 using a combination of terms for work, TBI, and epidemiology, without geographical limitations. Results Ninety-eight studies were included in this review, of which 24 specifically focused on wrTBI. In general, male workers, those in the youngest and oldest age groups, and those working in the primary (e.g., agriculture, forestry, mining) or construction industries were more likely to sustain wrTBI, with falls being the most common mechanism of injury. Conclusions This review identified workers at highest risk of wrTBI, with implications for prevention efforts. Future research of better methodological quality is needed to provide a more complete picture of the epidemiology of wrTBI. Am. J. Ind. Med. 58:353–377, 2015. ß 2015 Wiley Periodicals, Inc.
KEY WORDS: work-related; traumatic brain injury; epidemiology; systematic review; occupational health and safety
INTRODUCTION Traumatic brain injury (TBI) is a critical public health issue and a major cause of death and disability worldwide.
1
Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada Graduate Department of Rehabilitation Sciences, University of Toronto, Ontario, Canada 3 Department of Occupational Science and Occupational Therapy, University of Toronto, Ontario, Canada 4 Toronto Rehabilitation Institute, University Health Network, Toronto, Ontario, Canada Contract grant sponsor: Canadian Institutes of Health Research; Contract grant number: #CGW-126580 Correspondence to: Dr. Angela Colantonio, PhD, Department of Occupational Science and Occupational Therapy, University of Toronto, 160-500 University Avenue, Toronto, Ontario, Canada M5G 1V7. E-mail: [email protected] 2
Accepted 21 November 2014 DOI 10.1002/ajim.22418. Published online in Wiley Online Library (wileyonlinelibrary.com).
ß 2015 Wiley Periodicals, Inc.
Each year, an estimated 10 million people around the globe sustain a TBI leading to fatality or hospitalization [Hyder et al., 2007]. However, the true burden of TBI is likely much higher due to difficulty capturing mild cases not seeking medical care and the absence of injury surveillance systems in many parts of the world [Langlois et al., 2006; Hyder et al., 2007; Roozenbeek et al., 2013]. Instead of a single injury event, TBI has been increasingly recognized as a chronic health condition, as survivors are often faced with long-term or lifelong physical, cognitive, psychosocial and/or emotional impairments [Masel and DeWitt, 2010; Corrigan and Hammond, 2013]. In the US, it is estimated that at least 5.3 million people, or 2% of the population, are living with disabilities associated with TBI [Langlois et al., 2006]. The epidemiology of TBI has been well-documented [Bruns and Hauser, 2003; Tagliaferri et al., 2006; AbelsonMitchell, 2008; Summers et al., 2009; Roozenbeek et al., 2013]. In general, TBI has a higher occurrence in males and is more likely to affect young children, older adolescents and the
354
Chang et al.
elderly, with the leading causes being falls, motor vehicle collisions (MVC), struck by/against objects, and assaults/ violence. Additionally, TBI may occur in the workplace [Bruns and Hauser, 2003; Abelson-Mitchell, 2008]. According to data from the Bureau of Labor Statistics, the number of nonfatal occupational TBI cases in the US increased from 7,240 in 2009 to 11,830 in 2012 [BLS, 2014]. Similarly, in the Canadian province of Ontario, while the total number of workers’ compensation (WC) claims decreased over the years, the number of lost-time claims for TBI increased steadily from 1,503 (1.7%) in 2004 to 2,125 (3.9%) in 2013 [WSIB, 2014]. Work-related TBI (wrTBI) is considered among the most serious occupational injuries, leading to profound disruption of workers’ lives and significant economic burdens in terms of medical costs and lost wages [Kim et al., 2006; Colantonio et al., 2010]. Even workers sustaining mild TBI may experience longterm consequences, including challenges in daily activities and return to work [Chang et al., 2011]. Furthermore, it has been shown that wrTBI is significantly different from TBI that did not occur at work (non-wrTBI) in a number of demographic and injury characteristics [Kim et al., 2006]. This emphasizes the importance of identifying wrTBI-specific risk factors in order to inform targeted prevention strategies in work settings. However, while there is a wealth of literature, including reviews, on the epidemiology of TBI among professional athletes [Thurman et al., 1998; Pellman et al., 2004; Benson et al., 2011; Sahler and Greenwald, 2012] and military personnel [Ommaya et al., 1996; Okie, 2005; Warden, 2006; Cameron et al., 2012; Xydakis et al., 2012], research focusing on TBI among the general civilian workforce has been surprisingly sparse until recent years. Moreover, to date, there has not been a comprehensive review of the epidemiological literature on wrTBI, as previous narrative reviews focused primarily on treatment and outcomes from a clinical perspective [Daughton, 1990; Chang et al., 2011]. Given the devastating impacts of wrTBI on the workforce and the need to better understand its etiology for prevention purposes, we conducted a systematic review of the epidemiology of wrTBI. Specifically, this review aimed to describe the burden and demographic, occupational and injury characteristics of wrTBI based on a thorough synthesis of the literature, and critically appraise the quality of existing studies on wrTBI.
METHODS Literature Search Electronic databases MEDLINE, EMBASE, PsycINFO, and CINAHL were searched for the period 1980–2013 to identify English-language studies examining the epidemiology of wrTBI, with no restrictions on geographic location. A combination of search terms and subject headings relating to work, TBI, and epidemiology was used. Search terms for TBI
were selected with reference to a previously published systematic review protocol [Chan et al., 2013]. Search strategies used for each database are presented in Online Supplementary File I.
Inclusion and Exclusion Criteria Studies met inclusion criteria if they (1) provided quantitative information on the burden and/or risk factors (e.g., sex, age, industry, mechanism of injury) of wrTBI; (2) were primary research articles; (3) were published between January 1980 and December 2013; (4) were published in English; and (5) could be retrieved in fulltext. The date range was chosen to exclude older studies that may not reflect current working conditions. We excluded reviews; commentaries; case reports; conference abstracts; government reports with no methods reported; studies focusing on TBI among athletes or military personnel; and studies reporting treatment and/or clinical outcomes with no information on wrTBI risk factors. Studies were also excluded if TBI was not examined separately from neck, spinal cord, facial, and/or superficial head injuries (e.g., cuts and bruises).
Screening Process First, the title and abstract of all studies identified from the search were screened for potential inclusion by two authors (V.C.C. and E.N.G.) independently. Second, the full-texts of potentially eligible studies were retrieved and assessed for meeting inclusion criteria. Reference lists of included studies and relevant review articles were manually searched for additional studies that also met inclusion criteria. Any disagreement between authors was resolved through discussion and consensus or the help of a third author (A.C.).
Data Extraction The following information was extracted from studies that focused on the wrTBI population: study location/period, study type/design/methods, study population, sample size, data source, case definition/severity, and major epidemiologic findings including incidence/mortality, demographic characteristics, industry/occupation, and mechanism of injury. From studies where wrTBI was only a subset of the study population, the percentage of wrTBI was extracted or calculated.
Quality Assessment An assessment of study quality was performed on studies that focused on the wrTBI population, as data from these studies will be the main focus of the review. To assess quality, a 17-item checklist (Online Supplementary File II)
Work-Related Traumatic Brain Injury
was created by modifying items taken from two previously developed tools: one for primary research articles in general [Kmet et al., 2004] and the other specific to studies on occupational injuries/illnesses [Breslin et al., 2005]. Our checklist was designed to evaluate both the quality of reporting and study methodologies in the context of wrTBI. The main methodological considerations evaluated by the checklist included data source and method of subject selection; case definition (i.e., how “work”, “TBI”, and “fatality” were defined); measurement of burden (e.g., rates) and/or risk factors; and statistical analysis. A score of 0, 1, 2, or “N/A” (not applicable) was assigned to each item. Due to differences in the maximum possible score, both a fraction (out of 34 or less) and a percentage were calculated for each study for ease of comparison. Quality assessment was performed by two authors (V.C.C. and E.N.G.) independently, and disagreements were resolved by discussion until consensus was reached.
RESULTS The literature search yielded 8,063 records. After duplicates were removed, titles and abstracts of 6,266 articles were screened and 237 full-text articles were assessed for eligibility. Fifty-seven of these studies met the inclusion criteria and an additional 41 were identified from reference lists, totaling 98 studies included in this review. Of these studies, 24 focused specifically on wrTBI; 33 on work-related injuries, including a subset of TBI; 40 on all cases of TBI, including a subset that were work-related; and one on injuries in general, including estimates of wrTBI. A diagram detailing the search results is presented in Figure 1. Table I provides a summary of the 24 studies focusing on wrTBI, including results from the quality assessment. Of these studies, three (12.5%) were restricted to fatal cases; 12 (50%) included both fatal and nonfatal cases; and nine (37.5%) examined nonfatal cases only. Geographically, 11 (46%) studies were conducted in the US, 10 (42%) in Canada, and one (4%) in each of Great Britain, Hong Kong, and the United Arab Emirates. Moreover, two (8%) studies were published before 1990; six (25%) from 1990–1999; five (21%) from 2000–2009; and 11 (46%) in 2010 or later. Unless otherwise specified, the following sections pertain to findings from the 24 studies that focused on wrTBI only.
355
sectional design, seven (29%) were case series, and one (4%) used a historical cohort design. Additionally, 13 (54%) studies involved retrospective analysis of existing data, while 11 (46%) studies relied on chart reviews. Three studies that focused on wrTBI deaths used data from government inspection records [Janicak, 1998], coroners’ files [Tricco et al., 2006], or an occupational injury fatality database containing information from multiple sources [Tiesman et al., 2011]. The majority of the remaining studies (15 of 21; 71%) used data derived from WC claims, which may include medical billing records in addition to other administrative files. Hospitalbased data (e.g., trauma registries and medical records) were another commonly used data source, either alone or in combination with WC claims. TBI cases were defined using standard coding systems, such as the International Classification of Diseases (ICD) and/or WC-based codes, in 16 (67%) of the 24 studies. However, even when the same coding system was used, specific codes varied across studies. The remaining eight studies defined TBI using clinical diagnostic criteria without mention of codes or did not provide a clear definition of TBI.
Quality Assessment Quality assessment scores of the 24 wrTBI studies ranged from 53% to 94%: four studies scored below 70%, seven scored between 70% and 79%, nine scored between 80% and 89%, and four scored above 90%. Some of the most common methodological limitations were: insufficient description of the data source; biased/unrepresentative sample of the population of interest; low population coverage of the data source (e.g., 12 Mean ISS: wrTBI: 26.1 non-wrTBI: 27.1
Clinical or imaging evidence of WC claims (Washington brain injury, diagnosis of State Fund system), with concussion, or loss/alteration hospital billing records of consciousness; excluding closed head injury/fracture with none of the above; defined using diagnosisrelated group (DRG) codes or ICD-9 þ American National Standards Institute Z16.2 codes
Descriptive; cross-sectional Workers with wrTBI, (with incidence rate hospitalized within one calculated for each week of injury n ¼ 301 year); retrospective analysis of existing data
ICD-9-CM codes 800.0^801.9, 803.0^804.9, 850.0^854.1, 950.1^950.3, or 959.01 ISS: 0^8: 16% 9^15: 30% 16^24: 28% 25^75: 26%
Heyer and Franklin [1994] Washington State, US; 1988^1990
Data source
TBI case definition/severity measures
Trauma registry (WashingtonTrauma Registry) linked to WC claims (Washington State Fund) *All cases were identified from trauma registry data, and 71% were linked to WC data
Study population/sample size
Descriptive; cross-sectional; Adolescent and young adult retrospective analysis of workers (aged 16^24 existing data years) who sustained fatal (dead on arrival or in-hospital death) or nonfatal wrTBI involving inpatient admission of 48 hr, trauma resuscitation team activation, and/or interfacility transfer by emergency medical services n ¼ 273 (6% fatal)
Study type/design/ methods
Graves et al. [2013] Washington State, US; 1998^2008
Author [year]; Location/period
TABLE I. (Continued.)
^
9.4 per 100,000 FTE per year Decreasing trend overall
^
Incidence/mortality
Score: 28/34 (82%) Province-wide trauma registry data Large sample of TBI cases, with comparisons made between wrTBI and nonwrTBI cases Work-relatedness not defined Unclear source of denominators used for rate calculations (used male workers in Ontario, although study included both males and females)
wrTBI (n ¼ 950) Fall: 45% MVC: 21% Struck by/against: 16% Machinery: 9% Other: 9% 4% intentional (assault by firearms: 31%; fight or brawl: 25%; assault by other means: 25%) non-wrTBI (n ¼12,041) MVC: 68% Falls: 19% Struck by/against: 8% Other: 5% 11% intentional (fight or brawl: 36%; assault by other means: 27%; suicidal jump: 10%) wrTBI only (n ¼ 950) Construction: 37% Transportation: 15% Primary industry: 13% Manufacturing: 13% Sales/services: 10% Recreation/sports: 0.7% Medicine/Health: 0.5% Rate per 100,000 workers Primary industry: 9.4 Construction: 5.5 Manufacturing: 3.0 Transportation: 2.0 Sales/services: 1.5 Medicine/health: 0.8 Recreation/sports: 0.8 wrTBI (n ¼ 950) Sex: M: 94%; F: 6% Mean age: 38.9 Age groups 16^24: 13% 25^34: 23% 35^44: 27% 45^54: 23% 55^64: 14% non-wrTBI (n ¼12,041) Sex: M: 72%; F: 28% Mean age: 35.6 Age groups 16^24: 29% 25^34: 23% 35^44: 20% 45^54: 16% 55^64: 13%
(Continued )
Score: 28/32 (88%) WC system covered two thirds of workers in the state Explored the use of different combinations of codes forTBI case finding and checked a sample of original records Used length of stay as a proxy for injury severity No mention of fatal cases Fall: 49% (40% from elevation þ 9% on same level) Struck by/against: 30% (26% by þ 4% against) Highway MVC: 18% Caught in/under/between: 2% Highway, non MVC: 1% Explosion: 1%
Score: 32/34 (94%) Linkage of two populationbased data sources, capturing 85% of trauma victims Demonstrates undercover age of young workers by the WC system Potential misclassification of work-related injuries in trauma registry data
Quality assessment (score/ comments)
Selected industry-specific rates per 100,000 FTE per year Logging: 345.2 Roof work: 160.6 Garbage collecting: 127.2 Street and road construction: 116.6 Trucking: 94.4 Farms (dairy): 83.4 Interior finished carpentry: 82.8 Building construction: 68.1
Fall: 42% MVC: 23% Struck by/against: 16% Machinery: 3% Other: 16%
Mechanism of injury
Sex-specific rates per 100,000 FTE per year: M: 15.1; F: 2.4 Mean age: 36 (range: 14^75) Rates peaked in the 15^34 and 56^64 age groups
^
and 8 of Coleman, 1986.
Industry/occupation
Main findings
Sex: M: 87%; F: 13% Age groups 16^18: 15% 19^21: 37% 22^24: 48% Race/ethnicity White: 65% Latino /Hispanic: 19% Other: 4% Missing: 12%
Demographic characteristics
Work-Related Traumatic Brain Injury 359
Descriptive; cross-sectional Workers aged 16 who validation study; sustained fatal (dead on retrospective analysis of arrival or in-hospital death) or nonfatal wrTBI existing data involving inpatient admission of 48 hr, trauma resuscitation team activation, and/or interfacility transfer by emergency medical services, and had >3 days lost from work n ¼1,313 (9% fatal)
Sears et al. [2013] Washington State, US; 1998^2008
TBI cases admitted to a hospital, excluding deaths on arrival and deaths from other causes All TBI: n ¼ 581 wrTBI: n ¼ 56 (8% fatal)
Descriptive; case series; retrospective chart review
Salem et al. [2013] Abu Dhabi, United Arab Emirates; 2005^2009
Trauma registry (WashingtonTrauma Registry) linked to WC claims (Washington State Fund) *only included cases with both both data available
Different combinations of OIICS nature of injury (06, 086, 012, 08, 4, 9999), and part of body (01, 00/01/08, 0, 8) codes, compared to ICD-9-CM codes (800.0^801.9, 803.0^804.9, 850.0^854.1, 950.1^950.3, or 959.01)as the gold standard
ICD-9 codes based on CDC case definition of TBI GCS mild: 70% moderate: 9% Severe: 21%
Skull fracture (ICD-9 800^804), intracranial injury (ICD-9 850^ 854), or other injury with residual brain damage (e.g. anoxia due to electric shock or heat stroke) 60% had 2 days of unconsciousness
Selected subset of WC cases WC claim files from an involving TBI insurance carrier, postn ¼ 86 TBI survey questionnaire
Descriptive; case series; retrospective chart review and crosssectional survey
Medical records
Physical damage to, or functional impairment of, the cranial contents from acute mechanical energy exchange GCS: Mild: 79% Moderate: 11% Severe: 3%
Data source
TBI case definition/severity measures
Countywide emergency room/hospital admission records; coroners records, death certificates, nursing home and care facility records
Study population/sample size
Descriptive; cross-sectional; Fatal and nonfatal TBI cases retrospective chart among civilian and review military personnel aged 16 years, with a focus on male wrTBI cases All TBI: n ¼ 3,358 wrTBI: n ¼114(males: n ¼107, 7% fatal)
Study type/design/ methods
Mittelmann et al. [1991] Hartford, Connecticut, US; 1982^1989
Kraus and Fife [1985] San Diego County, California, US; 1981
Author [year]; Location/period
TABLE I. (Continued.)
^
^
^
19.8 per 100,000 male workers (9.9 per 100 million work hours)
Incidence/mortality
^
Sex: M: 100%; F: 0% Age groups 45: 11% Nationality Bangladeshi: 39% Indian: 20% Pakistani: 19% Egyptian: 15% Syrian: 6%
Sex: M: 94%; F: 6% Mean age: 36 (range: 15^70)
^
All cases, identified by ICD codes(n ¼1,313) Fall: 50% MVC: 20% Struck by/against: 15% Machinery: 4% Other: 11% Identified by the most sensitive OIICS-based definition (n ¼ 505) Fall: 47% Struck by/against: 24% MVC: 11% Machinery: 7% Other: 11%
Fall: 63% (80% from3m height) Struck by falling/moving object: 34% MVC: 4% By severity Mild: 51% fall; 44% struck; 5% MVC Moderate: 80% fall; 20% struck Severe: 92% fall; 8% struck
^
(Continued )
Score: 30/32 (94%) Linkage of two populationbased data sources Explored OIICS-based TBI case definitions Limited to severe cases with both trauma registry and WC data available Demonstrates undercount of wrTBI by WC data
Score: 22/30 (73%) Case series from a single hospital (limited generalizability) Work-relatedness not defined Mechanisms of injury stratified by injury severity
Score: 17/30 (57%) Biased and unrepresentative sample of wrTBI No information on how cases were selected for inclusion Use of non-TBI codes
Score: 29/34 (85%) Comprehensive coverage of records from different data sources (e.g., 95% of hospital beds) Not clear if standard codes were used to define TBI cases Work-relatedness not defined for civilian workers Females excluded
Civilian (n ¼ 65) Fall: 54% Struck by/against: 32% On-road MVC: 8% Firearms /assaults: 5% Off-road MVC: 2% Military (n ¼ 42) Off-road MVC: 36% On-road MVC: 21% Fall: 21% Struck by/against: 14% Firearms /assaults: 7% Fall: 41% Struck by object: 28% MVC: 19% Gunshot: 2% Other: 10%
Quality assessment (score/ comments)
Mechanism of injury
^
Civilian: 61% Military: 39% Rate per 100,000 male workers Civilian: 15.2 Military: 37.0 Rate per 100 million work hours Civilian:7.6 Military:18.5
Industry/occupation
Main findings
Sex: M: 94%; F: 6% Only males were included for further analysis (n ¼107) Rates decreased with increasing age for both civilian and military personnel
Demographic characteristics
360 Chang et al.
Colantonio and Comper [2012] Ontario, Canada; 1998^2001
Nonfatal only Colantonio et al.[2009] Ontario, Canada; 2004^2005
Descriptive; case series; retrospective chart review
Medical records and WC Workers with wrTBI, aged claim files (Ontario >15 years at time of WSIB) injury, have not returned to work 6 weeks postinjury, discharged from a WSIB-referred outpatient neurology service between 1998 and 2001 n ¼ 435
Descriptive; cross-sectional; Construction workers who WC claims (Ontario WSIB, retrospective analysis of sustained nonfatal wrTBI abstracted by the existing data resulting in days off Construction Safety work Association of Ontario) n ¼ 218 Sex: not reported Mean age: 35.8 Median age: 34 Age groups 17^24: 23% 25^34: 28% 35^44: 22% 45^54: 17% 55^64: 10%
Sex: M: 75%; F: 25% Age groups 44: 31% >44: 69% Married: 70% Less than high school education: 47%
^
Injury of appreciable magnitude to the head Most classified as ‘‘mild’’ Loss of consciousness: 52% (mostly 15 years at time of WSIB) injury, have not returned to work 6 weeks postinjury, discharged from a WSIB-referred outpatient neurology service between 1998 and 2011,with a focus on wrTBI due to falls Total wrTBI: n ¼ 435 Falls only: n ¼ 214
Head injury Most classified as ‘‘mild’’
TBI case definition/severity measures
Medical records and WC Workers with wrTBI, claims (Ontario WSIB) presented to the senior author between 1993^ 1997 with dizziness as the major complaint from an otoneurological perspective, referred by the WSIB, with 6 months follow-up from time of injury to date of initial neurotological assessment n ¼ 365
Medical records and WC Workers with wrTBI, aged claim files (Ontario >15 years at time of WSIB) injury, have not returned to work 6 weeks postinjury, discharged from a referral-based outpatient neurology service between 1998 and 2011,with a focus on construction workers Total: n ¼ 435 Construction: n ¼ 83
Study population/sample size
^
^
^
Incidence/mortality
Industry/occupation
Main findings
^
All falls (n ¼ 214) Occupations Trades/transport: 37% Professional/manager/ skilled: 34% Manufacturing: 17% General laborer: 13% Industries Construction: 25% Manufacturing: 19% Retail/wholesale: 14% Government/related services: 12% Transport/storage: 10% Primary industry/ mining: 5% Other: 15%
Sex: M: 83%; F: 17% Mean age at assessment: 45 (range: 18^71)
All falls (n ¼ 214) Sex: M: 71%; F: 29% Aged 45: 76% Did not complete secondary school: 47% Same level (n ¼115) Sex: M: 54%; F: 46% Aged45: 79% Did not complete secondary school: 39% From elevation (n ¼ 99) Sex: M: 90%; F: 10% Aged45: 73% Did not complete secondary school: 57%
Construction (19%) Construction (n ¼ 83) Trades/transport/ Aged45: 66% equipment operator: Married: 68% 55% Did not complete General laborer: 41% secondary school: 64% Other (81%) Speaks English or Trades/transport/ French: 65% equipment operator: Immigrant: 47% 35% Other (n ¼ 352) General laborer: 5% Aged45: 69% Other: 60% Married: 71% Did not complete secondary school: 43% Speak English or French: 70% Immigrant: 50%
Demographic characteristics
Fall: 49% of all wrTBI Same level: 54% From elevation: 46% Agent in contact with head: Working area: 80% Unboxed material: 12% Human/vehicle: 4% Tools/machinery: 2%
Fall: 47% Struck by/against: 35% MVC: 12% Assault: 4% Explosion: 2%
Construction (n ¼ 83) Fall: 66% (59% from elevation þ 7% on same level) Struck by object: 36% Struck against object/ building: 11%/8% MVC: 6% Other (n ¼ 352) Fall: 46% (15% from elevation þ 31% on same level) Struck by object: 36% Struck against object/ building: 13%/12% MVC: 13%
Mechanism of injury
(Continued )
Score: 21/28 (75%) Generalizable only to WSIB insured cases with persistent symptoms and those who have not returned to work Lacked a clear definition of TBI and injury severity Validated tool used for data abstraction Comparisons of wrTBI cases by type of fall
Score: 20/28 (71%) Convenience sample with very specific inclusion criteria ^ not generalizable to all wrTBI cases No clear definition of TBI (i.e., no codes used) although severity grades were assigned based on type of TBI Data source not sufficiently described
Score: 23/28 (82%) Generalizable only to WSIB insured cases with persistent symptoms and those who have not returned to work Lacked a clear definition of TBI and injury severity Validated tool used for data abstraction Comparisons made between wrTBI cases in construction vs. other industries
Quality assessment (score/ comments)
Work-Related Traumatic Brain Injury 363
TBI, traumatic brain injury; wrTBI, work-related TBI; WC, workers’compensation; WSIB,Workplace Safety and Insurance Board; OIICS, Occupational Injury and Illness Classification System; ICD, International Classification of Diseases; ICD-9-CM, ICD, 9th revision, Clinical Modification; ISS, Injury Severity Score; GCS, Glasgow Coma Scale; CDC, Centers for Disease Control and Prevention; FTE, full-time equivalent; M, male; F, female; MVC, motor vehicle collision. Note that some information may be missing (i.e., not reported or not applicable) from each study.
Fall: 46% MVC: 29% Struck by object: 14% Assault: 5% Machinery: 3% ^ Sex: M: 76%; F: 24% Age groups 18^24: 13% 25^34: 16% 35^44: 22% 45^54: 18% 55^64: 14% 65: 17% 6.2 per 100,000 workers per year Decreasing trend overall ICD-9-CM codes established in Minnesota Rules, including codes used by the CDC and other codes associated with TBI
Incidence/mortality Data source
Descriptive; cross-sectional; Nonfatal hospital-admitted TBI registry (MinnesotaTBI Registry) retrospective analysis of cases of wrTBI, aged existing data 18 years and injured while working for income n ¼1,722 Wei et al. [2012] Minnesota, US; 1999^2008
Mechanism of injury Industry/occupation
Main findings
Demographic characteristics TBI case definition/severity measures Study population/sample size Study type/design/ methods Author [year]; Location/period
TABLE I. (Continued.)
Score: 26/32 (81%) Population-based TBI registry TBI codes used were not clearly stated Potential misclassification of work-related injuries in medical records Rates not calculated by subgroups (e.g., sex, age)
Chang et al. Quality assessment (score/ comments)
364
database of occupational fatalities between 2003 and 2008, the mortality rate of wrTBI was estimated at 0.8 per 100,000 workers per year [Tiesman et al., 2011]. In an Ontario study using coroners’ records of wrTBI fatalities, a rate of 6.45 per 100,000 male workers was reported over a 5-year period 1996–2000 [Tricco et al., 2006]. This averaged to 1.3 per 100,000 per year, which is similar to the malespecific mortality rate (1.5 per 100,000 per year) reported in the US [Tiesman et al., 2011].
Severity and case fatality Seven studies presented data on the severity of wrTBI cases, assessed using measures such as the Glasgow Coma Scale (GCS), Injury Severity Score (ISS), and duration of loss of consciousness and/or post-traumatic amnesia. Specifically, two studies using hospital records showed that the majority (>70%) of hospitalized wrTBI cases were mild (i.e., GCS 13–15) [Kraus and Fife, 1985; Salem et al., 2013], while studies using trauma registry data had more severe cases as defined by the ISS [Kim et al., 2006; Graves et al., 2013]. In nine studies, the percentage of fatal cases (i.e., case fatality rates) ranged from 4% to 11%.
Demographic characteristics Across all studies presenting data on sex distribution, males comprised a greater proportion of wrTBI cases than females. However, relative proportions varied according to the degree of injury severity. In the only study examining sex distribution of wrTBI fatalities, 93% of cases were males [Tiesman et al., 2011]. Similarly, in seven studies examining hospitalized/fatal wrTBI, males accounted for 87–100% of cases. When restricted to nonfatal cases, the proportion of males ranged from 64% to 83% across seven studies, with the lowest percentages (80%) involved falls from an elevation [Heyer and Franklin, 1994; Cohen et al., 1999; Wrona, 2006; Salem et al., 2013], while falls from the same level were more common among nonfatal and less severe cases [Colantonio et al., 2010; Wei et al., 2010; Liu et al., 2011]. MVC and being struck by/against were also among the top three causes of wrTBI. In general, MVC were more common among fatal and/or severe cases compared to being struck/by against [Kim et al., 2006; Wrona, 2006; Tiesman et al., 2011; Graves et al., 2013; Sears et al., 2013]. Unlike falls, MVC were more common among younger workers [Kim et al., 2006; Wei et al., 2012] and were the leading cause of fatal wrTBI in workers below 55 years of age and in the transportation/warehousing industry [Tiesman et al., 2011]. Being struck by/against was the leading cause of wrTBI when a wider range of severity levels were examined [Colantonio et al., 2010]. It also occurred more frequently among younger workers [Mittelmann et al., 1991; Kim et al., 2006; Colantonio et al., 2009, 2010; Tiesman et al., 2011] and was the leading cause of severe and/or fatal wrTBI in the primary industries [Kim et al., 2006; Tiesman et al., 2011]. Other notable mechanisms of injury included assaults/ violence, machinery incidents, and being caught/crushed. In particular, assaults accounted for 2–5% of wrTBI cases according to six studies [Kraus and Fife, 1985; Mittelmann et al., 1991; Ogawa and Rutka, 1999; Kim et al., 2006; Wrona, 2006; Wei et al., 2012], and 10–20% of wrTBI fatalities according to two studies [Wrona, 2006; Tiesman et al., 2011]. Specifically, Tiesman et al. [2011] found that more than 40% of wrTBI deaths among women were caused by assaults or violent acts, including self-inflicted injuries.
1982^1986 1990^1992 1980^1985
Washington State, US
New York State, US Massachusetts, US Washington State, US Greece
Washington State, US
Washington, DC, US Washington and Alaska, US
Sears et al. [2011]
Belville et al. [1993] Brooks and Davis [1996] Miller and Kaufman [1998] Alexe et al. [2003]
Demers and Rosenstock [1991] Hunting et al. [1994] Holman et al. [1987]
1980^1987 1987^1990 1988^1991 1996^2000
1998^2008
2009 Feb^ Aug
Taiwan
Lin et al. [2012]
2002^2006
US
Konstantinidis et al. [2011]
1989 Jan^ Feb
1980^1989 1990^1999 1990^2001 1991^1994 1991^1994 1992^2000
Aberdeen, UK
Dunn and Runyan [1993] Etiler et al. [2004] Colak et al. [2004] Jeong [1998] Jeong [1997] Scott [2004]
2003^2008 1996^2000
1997^2003
North Carolina, US Kocaeli,Turkey Kocaeli,Turkey South Korea South Korea US
Tiesman et al. [2011] Tricco et al. [2006]
1986^1989
1994^1996 1998^2008
1979^1983
1978
Study period
Illinois, US
US Ontario, Canada
Shannon et al. [1993]
Fatal/nonfatal Friedman and Forst [2008] Harker et al. [1991]
Ontario, Canada
Janicak [1998] Sears et al. [2013]
Maryland, US
Location
Metro Dade County, Florida, US US Washington State, US
Copeland [1985]
Fatal only Baker et al. [1982]
Author [year]
TABLE II. Proportion of Work-Related Injuries Identified asTBI
592 51
25,097
9,656 2,551 15,051 2,367
9,185
4,403
67,658
578
17,422
71 387 153 3,028 2,533 780
33,641 488
470
3,202 NR
147
148
Sample sizea
Construction workers Loggers
Agricultural workers
Adolescent workers (14^17 y) Adolescent workers (14^17 y) Adolescent workers (11^17 y) Farm workers
Workers
Workers
Workers
Workers
Workers
Adolescent workers (900 centers)
Statewide trauma registry
Medical examiners’ records Occupational injury registry records Occupational injury registry records National industrial accident statistics National industrial accident statistics Census of Fatal Occupational Injuries
Coroners’ records and Ministry of Labor fatality inspection records Census of Fatal Occupational Injuries Coroners’ records
Occupational fatality inspection records Trauma registry linked to WC claims data
Medical examiners’ records, WC claims, occupational agency reports, vital records Medical examiners’ records
Data source
2% 43%
0.4%
0.6% 0.5% 0.7% 3%
21%
11%
16%
0.3%
9%
34% 24% 26% 19% 12% 43%
22% 45%
6%
27% 60%
25%
21%
% TBI
(Continued )
Head injury/concussion (ICD-9 codes) Head injury (skull fractures, concussions, major
Concussion
TBI (ICD-9-CM 800.0^801.9, 803.0^804.9, 850.0^854.1, 950.1^950.3, 959.01) Concussion Concussion (ANSI codes) Concussion (ANSI codes) Concussion
TBI, including concussion, fractured skull, intracranial hemorrhages, and other head injury Intracranial injury
Concussion
TBI involving internal injury (ICD-9 N codes)
Death due to head injury Death involvingTBI (ICD-9-CM 800.0^801.9, 803.0^804.9, 850.0^854.1, 950.1^950.3, 959.01) Intracranial injury (ICD-9 N codes), as either the first or second injury specified TBI accounting for death (OIICS codes) Injuries included TBI (ICD-9 N800^804, 850^ 854) Blunt head trauma as mechanism of injury Head trauma as cause of death Head trauma as cause of death Concussion as nature of injury Cerebral concussion as nature of injury Head as part of body injured which led to death
Craniocerebral trauma as cause of death
Head injury as the only severe injury causing death
TBI case definition
366 Chang et al.
Massachusetts, US South Korea South Korea Umea , Sweden
North Carolina, US St. Louis, Missouri, US Australia Australia
Brooks et al. [1993] Jeong [1998] Jeong [1997] Bylund and Bj€ornstig [1998]
Kucera et al. [2010] Lipscomb et al. [2003] Lucas et al. [2009b] Lucas et al. [2009a]
1999^2001 1999^2002 1960^ 1960^
1979^1982 1991^1994 1991^1994 1985
1986 2001^2004 1997^1999
1980^1981
1995^2003 2006^2008
1990^1999
Study period
125 117 2,188 453
1,176 125,929 186,726 398
31,588 467 5,546,000
11,586,000
15,113 306
33
Sample sizea
Fishermen Carpenters (falls only) Veterinarians Veterinarians (horse-related injuries only)
Adolescent workers (14^17 y) Construction workers Manufacturing workers Mechanics and construction metal workers
Workers Workers Workers
Workers
Male goods-transport drivers Workers (ladder falls only)
Loggers
Injured worker population
National probability survey (household interview) WC claims Hospital records and questionnaire National probability survey (household interview) ED and hospital admission records National industrial accident statistics National industrial accident statistics Hospital records, occupational agency reports, WC claims Telephone interviews Questionnaire Questionnaire Questionnaire
Occupational hospitalization registry National injury surveillance system (65 ED) and questionnaire
Medical records from 1trauma center
Data source
Concussion Concussion Intracranial injury Intracranial injury
Concussion/cranial injury (ICD-9-CM codes) Concussion Cerebral concussion Concussion
Skull fractures and intracranial injuries (ICD-9 800^804, 850^854) Brain concussion (ANSI codes) Brain trauma Skull/brain as body region injured
brain injuries) Head injury (concussion, skull fractures, subarachnoid hemorrhage) Concussion (ICD-10 S06.0) Concussion
TBI case definition
1% 2% 3% 6%
2% 3% 1% 0.8%
0.6% 6% 3%
3%
1% 3%
48%
% TBI
TBI,traumaticbraininjury;WC,workers’compensation;ED,emergencydepartment;ICD,InternationalClassificationofDiseases;ICD-9-CM,ICD,9threvision,ClinicalModification;OIICS,OccupationalInjuryandIllnessClassification System; ANSI, American National Standards Institute; NR, not reported. a Sample size refers to the denominator (i.e., total number of work-related deaths or injuries) used to determine the percentage of TBI.
Washington State, US Guangzhou, China US
Fulton-Kehoe et al. [2000] Li et al. [2008] Smith et al. [2005]
US
Denmark US
Shibuya et al. [2008] Lombardi et al. [2011]
Nonfatal only Collins [1986]
Pennsylvania, US
Location
Johnson et al. [2002]
Author [year]
TABLE II. (Continued.)
Work-Related Traumatic Brain Injury 367
Al-Ain city, United Arab Emirates
Virginia, US Olmsted County, Minnesota, US
St Gallen, Switzerland
Sfax,Tunisia Veneto Region, Italy
Toronto, Ontario, Canada
NorthwesternTanzania
Hualien County, Taiwan
Ontario, Canada
New South Wales, Australia
Trndelag, Norway
Sydney, Australia King County, Washington, US
US
Ontario, Canada
San Diego County, California, US
Alberico et al. [1987] Annegers et al. [1980]
Annoni et al. [1992]
Bahloul et al. [2004] Baldo et al. [2003]
Cadotte et al. [2011]
Chalya et al. [2011]
Chiu et al. [1995]
CIHI [2004]
Dan et al. [1986]
Edna and Cappelen [1984]
Fearnside et al. [1993] Gale et al. [1983]
Jager et al. [2000]
Kim et al. [2006]
Kraus and Fife [1985]
Dharan, Nepal
Fatal/nonfatal Agrawal et al. [2009]
Location
Al-Kuwaiti et al. [2012]
Tabriz, Iran
Fatal only Bavil [2008]
Author [year]
1981
1993^2001
1992^1994
NR 1980^1981
1979^1980
1977^1978
2001^2002
1988^1991
2008^2010
1986^2007
1997^1999 1996^2000
1987
1976^1984 1935^1974
2003^2006
2005
1999^2004
Study period
TABLE III. Proportion of Traumatic Brain Injuries Identified as Work-Related
3,358
12,991
1,144,807
315 451
1,124
126
2,489
5,378
260
9,315
437 32,919
80
230 3,587
589
334
216
Sample sizea
Trauma registry (single center) Questionnaire from a hospital ED Admission records from 4 major hospitals, medical examiners’ reports, death certificates Provincial trauma registry (lead trauma hospitals) Statewide hospital records and death certificates Population-based hospital admission records
Medical records from 1hospital ED/hospital records from a regional trauma center National probability survey of ED visits
14 0 8 0 0
0 0
0
16^64
0
0
0
Provincial trauma registry (lead trauma hospitals) Population-based ED/hospital records, coroners’ records, death certificates,
Medical records from regional neurosurgical units Medical records from a hospital ICU Population-based hospital records
0
0
Medical records from 1hospital Countywide medical records linkage system, including death certificates and autopsy reports
Trauma registry (single center)
0
20^80 0
Medical records from a surgery department
Autopsy reports from 1hospital
Data source
0
0
Age (year)
3%
7%
4%
1% 4%
5%
3%
4%
12%
0.4%
5%
4% 9%
10%
2% 4%
14%
0.6%
6%
% WR
(Continued )
ICD-9-CM 800.0^801.9, 803.0^804.9, 850.0^ 854.1 ICD-9-CM 800.0^801.9, 803.0^804.9, 850.0^ 854.1; ISS >12 Physical damage to, or functional impairment of, the cranial contents from acute
ICD-N 800, 801, 803, 804, 850, 851, 852, 853, 854; ISS >12 Extradural hematoma occurring alone, with no other hematoma Physical injury to the brain or skull caused by external force, with LOC, skull fracture, or development of intracranial hematoma SevereTBI (GCS 8) Mild/moderate/severeTBI (based on GCS)
Mild/moderate/severeTBI (defined by period of LOC and PTA) Head injury (concussion, fractured skull, subdural/epidural hematoma, subarachnoid bleeding, intracerebral hemorrhage, brain contusion) SevereTBI (GCS 7) Head injury with evidence of presumed brain involvement: concussion with LOC, PTA, or neurological signs of brain injury; skull fracture Intracranial lesions shown on admission CT scan Mild/moderate/severeTBI (based on GCS) ICD-9-CM 800.0^801.9, 803.0^804.9, 850.0^ 854.1 ISS >12 and Head Abbreviated Injury Scale (HAIS) score >0 Blunt or penetrating injury affecting the cranium and its contents ICD-9 800, 801, 803, 804, 850, 851, 852, 853, 854
Death due to severe head injury before or after admission
TBI case definition/severity
368 Chang et al.
Hanover and M€unster, Germany
New South Wales, Australia
Austria Abu Dhabi, United Arab Emirates US
Romagna and Trentino, Italy
New South Wales, Australia
New South Wales, Australia
New South Wales, Australia
Autonomous Region of Cantabria, Spain
Oulu and Lapland, Finland
Toronto, Ontario, Canada
Hong Kong Calgary Health Region, Alberta, Canada
Rickels et al. [2010]
Ring et al. [1986]
Rosso et al. [2007] Salem et al. [2013] Schootman and Fuortes [2000]
Servadei et al. [2002]
Stening et al. [1986a]
Stening et al. [1986b]
Vanderfield et al. [1986]
Va´zquez-Barquero et al. [1992]
Winqvist et al. [2008]
Wong et al. [1993]
Yue et al. [1983] Zygun et al. [2005]
New Zealand
12 European countries Australia and New Zealand Kingston, Ontario, Canada
Murray et al. [1999] Myburgh et al. [2008] Pickett et al. [2001]
Nonfatal only Alexander et al. [2007]
Taiwan
Location
Lee et al. [1990]
Author [year]
TABLE III. (Continued.)
2003^2004
1970^1981 1999^2002
1978^1991
1978^2000
1988
1977^1978
1977^1978
1977^1978
1998
2001^2003 2005^2009 1995^1997
1977^1978
2000^2001
1995 Feb^ Apr NR 1998
1977^1987
Study period
161
60 241
456
236
477
135
290
129
R: 2,880 T: 1,562
391 581 1,400,000
991
6,783
996 635 202
10,000
Sample sizea
Statewide hospital records and death certificates Hospital admission records from 5 hospitals Admission records from 1hospital National probability survey of ambulatory care (ED, outpatient, physicians’ office) visits Population-based hospital admission records
0
NR
0 18
18
12
0
0
0
0
0
Medical records from a concussion clinic
Hospital records from a general surgical unit Population-based records from a tertiary care trauma center and all acute care facilities
Population-based hospital discharge registry, hospital records, questionnaire (birth cohort) Medical records from 1hospital
Statewide hospital records and death certificates Statewide hospital records and death certificates Statewide hospital records and death certificates Population-based hospital admission records
Population-based hospital ED records
0
0 NR 0
Survey completed by 67 neurosurgical centers Case reports from ICU of major trauma centers Population-based surveillance program, ED and inpatient care records from all hospitals
nursing home records Admission records from a major hospital
Data source
>16 >16 0
0
Age (year)
External force to the head, mild/moderate/ severeTBI
7%
15% 6%
0.7%
3%
8%
3%
2%
6%
R: 8% T: 2%
7% 10% 7%
3%
15%
6% 1% 3%
3%
% WR
(Continued )
Acute/subacute subdural hematoma occurring alone, with no other hematoma Chronic subdural hematoma occurring alone, with no other hematoma Head injury with LOC, skull fracture, or objective neurologic findings ICD-8 and ICD-9 N codes 800, 801, 803, 850, 851^854; or ICD-10 S02.0^ S02.11, S06.0^ S06.9, S07.1 Medical diagnosis of TBI with potential for rehabilitation Extradural hematoma SevereTBI (GCS 8, requiring intracranial pressure monitoring, or presence of clinical/radiographic herniation) and ISS 12
ICD-9 800.0^800.3, 801.0^801.3, 803.0^ 803.3, 850, 851.0^851.1, 852.0^852.1, 853.0^853.1, 854.0^854.1 Multiple intracranial hematomas
mechanical energy exchange Head injury with LOC, PTA, clinical signs of focal brain lesion, and/or evidence of traumatic intracranial lesions by CTscan Moderate/severeTBI (GCS 12) Mild/moderate/severeTBI (based on GCS) Blunt head trauma resulting in LOC, PTA, or disorientation; skull fracture; intracranial injury; or head injury resulting in hospitalization Acute head injury with clinical symptoms; ICD10 S02, 04, 06, 07, 09 ICD-8 851^3, 800^804, 850, 854; operation codes SevereTBI (GCS 8) ICD-9 codes, based on CDC’s definition of TBI ICD-9-CM 800^801, 803^804, 850^854
TBI case definition/severity
Work-Related Traumatic Brain Injury 369
18
1,255
62
1,381
357
495
NR
1993^1998
1992^1993
2003^2005
2002^2004
1983
1999^2008
US
Staffordshire, UK
Reading, UK
Internet-based, mainly US
Christchurch, New Zealand
6 cities in China
Minnesota, US
Collins [1986]
Haboubi et al. [2001]
Powell et al. [1996]
Setnik and Bazarian [2007]
Snell and Surgenor [2006]
Wang et al. [1986]
Wei et al. [2012]
TBI, traumatic brain injury; WR, work-related; ICU, intensive care unit; ED, emergency department; LOC, loss of consciousness; PTA, post-traumatic amnesia; GCS, Glasgow Coma Scale; CT, computerized tomography; ICD, International Classification of Diseases; ICD-9-CM, ICD, 9th revision, Clinical Modification; ISS, Injury Severity Score; CDC, Centers for Disease Control and Prevention; NR, not reported. a Sample size refers to the denominator (i.e., total number of TBI cases) used to determine the percentage of TBI that were work-related.
0
4% StatewideTBI registry
16
24% Door-to-door survey, medical records
13
6%
Internet-based survey on a patient-oriented website of a medical center Medical records from a concussion clinic
>16
13%
Medical records from 1hospital
16^65
7%
14%
Skull fractures and intracranial injuries (ICD-9 800^804, 850^854) Mild TBI (GCS 13^15), seen in ED or admitted to hospital for
