Asia-Pacific Journal of Public Health http://aph.sagepub.com/
Work-Related Musculoskeletal Disorders Among Sugarcane Farmers in Northeastern Thailand Teerasak Phajan, Kessarawan Nilvarangkul, Dariwan Settheetham and Wongsa Laohasiriwong Asia Pac J Public Health published online 21 March 2014 DOI: 10.1177/1010539514528026 The online version of this article can be found at: http://aph.sagepub.com/content/early/2014/03/20/1010539514528026.citation A more recent version of this article was published on - May 13, 2014
Published by: http://www.sagepublications.com
On behalf of:
Asia-Pacific Academic Consortium for Public Health
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528026 research-article2014
APHXXX10.1177/1010539514528026Asia-Pacific Journal of Public HealthPhajan et al
Original Article
Work-Related Musculoskeletal Disorders Among Sugarcane Farmers in North-Eastern Thailand
Asia-Pacific Journal of Public Health 1–8 © 2014 APJPH Reprints and permissions: sagepub.com/journalsPermissions.nav DOI: 10.1177/1010539514528026 aph.sagepub.com
Teerasak Phajan1, Kessarawan Nilvarangkul, PhD, REQW1, Dariwan Settheetham, PhD1, and Wongsa Laohasiriwong, PhD1
Abstract This cross-sectional analytical study aimed to identify prevalence and factors associated with work-related musculoskeletal disorders (WMSDs) among sugarcane farmers. Cluster random sampling was used to select 540 sugarcane farmers from 3 provinces in North-Eastern Thailand. Three related questionnaires, plus assessments by 2 expert physiotherapists, were used to check for factors associated with WMSDs and prevalence of WMSDs. Data were analyzed using descriptive statistics and multiple logistic regressions. The results indicated the prevalence of WMSDs among sugarcane farmers in the 7 days before the interview and looking back over the previous 12 months were 82.96% and 88.70%, respectively. Factors significantly associated with reporting WMSDs (P value < .05) during past 12 months were (a) repetitive motions (adjusted odds ratio [OR] = 1.90; 95% confidence interval [CI] = 1.05-3.43), (b) working in awkward postures (adjusted OR = 1.95; 95% CI = 1.01-3.77), (c) forceful exertions (adjusted OR = 2.78; 95% CI = 1.54-5.02), and (d) stress about future income (adjusted OR = 1.80; 95% CI = 1.023.16). Recommendations are made for risk prevention strategies. Keywords musculoskeletal disorders, working postures, repetitive work, forceful exertions, financial stress, sugarcane farmers, Thailand
Introduction Work-related musculoskeletal disorders (WMSDs) are a common health problem among the general working population. In Thailand, there are approximately 274 832 cases of WMSDs per year.1 These disorders raise the cost of workers’ compensation by approximately 11 000 million baht per annum (US$333 million per annum). It should also be noted that the cost of lost time associated with WMSDs is often overlooked and unaccounted for.2 The symptoms of WMSDs are typically stress, sickness, a noticeable decrease in overall physical activity levels, the inability to perform certain other physical activities, decreased working efficiency, and a low quality of life.3-5
1Khon
Kaen University, Khon Kaen, Thailand
Corresponding Author: Kessarawan Nilvarangkul, Faculty of Nursing, Khon Kaen University, Khon Kaen 40002, Thailand. Email: [email protected]
Downloaded from aph.sagepub.com at PENNSYLVANIA STATE UNIV on May 26, 2014
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Asia-Pacific Journal of Public Health
In Thailand, sugarcane work is seasonal. During the growing period from November until April, the workforce is never less than 600 000 persons.6 Sugarcane farmers are directly involved in the production process and are therefore exposed to most of the associated risk factors. The few existing studies show that sugarcane work is characterized by extreme repetition, forceful movements, continuous body contortions, awkward postures, high workloads, and psychosocial pressures.7,8 However, little research has been carried out to investigate the risk factors associated with WMSDs in North-Eastern Thailand. Moreover, there is a gap in such knowledge because few basic statistics are available on the prevalence of WMSDs among the general working population. This study therefore aimed to identify the prevalence of WMSDs among sugarcane farmers in Thailand and the factors associated with increased morbidity. This article analyses factors associated with risk exposure, drawing on questionnaire data, and discusses strategies for mitigating these risks.
Methods Recruitment of Subjects This study was a cross-sectional analytical survey administered to sugarcane farmers working in North-Eastern Thailand. The required sample size was estimated using a formula for multiple logistic regression to identify relationships between multiple independent variables and a dichotomous dependent variable.9 Cluster random sampling was applied to select 540 sugarcane farmers spread across a study of 3 provinces (Khon Kaen, Nakhon Ratchasima, Udon Thani). See Figure 1. The inclusion criteria for participants was that they engaged in at least one activity ranging from cutting, tightening, applying fertilizer, lifting cane onto loading trucks, weed control, had worked in that activity for at least 1 year, and were between 18 and 59 years old. Potential participants were excluded if they had a preexisting diagnosis of either bone or muscle disease, such as gout, arthritis, rheumatism, osteoporosis, osteoarthritis, myasthenia gravis, immune deficiency, menopausal syndrome, or had received surgery for a bone or muscle disorder. Data were collected between October 25, 2012, and January 15, 2013.
Research Instruments The study used separate questionnaires to assess (a) workers’ perceptions of the importance of the physical, environmental, and psychosocial risk factors that were associated with WMSDs and (b) the extent of pain and disability suffered by those workers. An initial screening questionnaire was also applied to identify subjects for inclusion in the study and to distinguish workers who were actually affected by WMSDs from those experiencing other illnesses. A questionnaire dealing with background demographic data was developed by the researcher, with 3 sections dealing with physical, environmental, and psychosocial risks. This was pretested with 30 sugarcane farmers in Sahatsakhan district, Kalasin province. Reliability was assessed using Cronbach’s α, yielding a score of .84, which was judged acceptable. Six experts commented on the draft questionnaire, and revisions were made to improve its validity. The Standardized Nordic Questionnaire10 measured the respondents’ subjective perceptions of disability and pain and was used alongside the purpose-designed questionnaire on risk factors to examine the relationship between risk exposure and WMSDs. It was chosen because it could identify body region disorders (neck, shoulder, elbow, wrist, upper back, low back, hip, knee, ankle, and foot) experienced in either the past 7 days or the last 12 months. The tool is widely used worldwide and is generally considered to be highly reliable, for example, achieving a reliability of .90.11 In Thailand, it has been calculated that the instrument had a reliability of .80.12
Downloaded from aph.sagepub.com at PENNSYLVANIA STATE UNIV on May 26, 2014
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Phajan et al
Figure 1. Map of the 3 provinces studied in North-Eastern Thailand.
It was realized that self-reported pain would be affected by respondents’ differential pain tolerance thresholds, which might result in low reporting of WMSDs even where the range of motions could be considered abnormal. Thus, the results of the Nordic Standardized Questionnaire were supplemented by musculoskeletal examinations performed by 2 expert physiotherapists who assessed the range of motions achievable (this term refers to the extent to which a joint or group of muscles can be flexed or extended). Thus, the questionnaire responses were analyzed alongside the forms completed by the 2 expert physiotherapists recording the results of the musculoskeletal examination (mainly relating to range of motion).
Data Analysis After data collection, the data were validated, coded, and analyzed using the statistical application package STATA version 10.0. Descriptive statistics were used to examine the characteristics of sugarcane farmers and the prevalence of WMSDs. Associations between independent variables and WMSDs were analyzed using the χ2 test, and multiple logistic regression analysis was applied to determine the adjusted odds ratio with a 95% confidence interval.
Research Ethics The proposal and the tools were submitted and approval was granted by the Ethics Committee of Khon Kaen University (Reference No. HE 552186).
Downloaded from aph.sagepub.com at PENNSYLVANIA STATE UNIV on May 26, 2014
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Asia-Pacific Journal of Public Health
Table 1. The Prevalence of WMSDs Among Sugarcane Farmers in the Past 7 Days and the Last 12 Months (n = 540). In the Past 7 Days WMSDs No Yes 1 sitea 2 sites 3 sites 4 sites 5 sites 6 sites 7 sites 8 sites 9 sites
In the Last 12 Months
Number
Prevalence (95% CI)
Number
Prevalence (95% CI)
92 448 115 138 81 50 25 27 7 4 1
17.04 (13.96-20.47) 82.96 (79.52-86.03) 25.67 (22.10-29.64) 30.80 (26.87-34.82) 18.08 (14.98-21.66) 11.16 (8.58-14.07) 5.58 (5.14-5.99) 6.03 (5.61-6.45) 1.56 (1.26-1.89) 0.89 (0.66-1.16) 0.22 (0.11-0.38)
61 479 119 128 83 54 42 23 21 6 3
11.30 (8.75-14.27) 88.70 (85.72- 91.24) 24.84 (21.22-28.68) 26.72 (22.98-30.61) 17.33 (14.30-20.87) 11.27 (8.75-14.27) 8.77 (84.71-90.41) 4.80 (4.367-52.27) 4.38 (3.96-4.81) 1.25 (1.00-1.56) 0.63 (0.43-0.86)
Abbreviations: WMSD, work-related musculoskeletal disorder; CI, confidence interval. aNumber of site, for example, 1 site means a sugarcane farmer has WMSDs at 1 position: neck or hip; 2 sites mean a sugarcane farmer has WMSDs at 2 positions: knee and hip or hip and shoulder.
Results Characteristics of the Study Sample A total of 57.59% of the respondents were females. The average age was 44.75 ± 7.67 years; 95.00% were married, and 62.59% had finished primary education. Respondents had an average body mass index of 24.30 ± 3.79 kg/m2.
Prevalence of Musculoskeletal Disorders in Sugarcane Farmers The majority of respondents perceived they had experienced WMSDs in the past 7 days and in the last 12 months, and the results are given in Table 1. Data for those who had experienced WMSDs in the past 7 days, in the last 12 months, and sickness absences in the last 12 months are given in Figure 2.
Factors Associated With Work-Related Musculoskeletal Disorders Among Sugarcane Farmers Bivariate analysis showed statistically significant associations between WMSDs in last 12 months factors. Bivariate analysis was selected for the multivariate modeling process, and the results are given in Table 2. Multivariate analysis using multiple logistic regression analysis indicated statistically significant associations between suffering WMSDs in last 12 months and several factors (P value < .05), and the results are given in Table 3.
Discussion The prevalence of WMSDs among sugarcane farmers in this study was 88.70% (Table 1). The farmers had WMSDs in their low backs (58.70%), shoulders (42.96%), and wrists (32.22%; Figure 2). This result was higher than other studies related to farmers in Malaysia (58.30%)13 and
Downloaded from aph.sagepub.com at PENNSYLVANIA STATE UNIV on May 26, 2014
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Phajan et al
Figure 2. The prevalence of WMSDs in the past 7 days, in the past 12 months, and for sickness absences in the last 12 months. Table 2. Unadjusted ORs of Having WMSDs of Sugarcane Farmers and Their 95% CIs for Each Factor (n = 540). Factors
OR
95% CI
P Value
Extending or twisting the wrist repeatedly for more than 2 hours total per day (Yes = 1, No = 0) Repetitive motions: worker repeats the same motion with the neck, shoulder, elbows, wrists, or hand for more than 2 hours total per day (Yes = 1, No = 0) Work that entails prolonged standing for more than 4 hours per day (Yes = 1, No = 0) Exerting or squeezing the hand continuously for more than 2 hours total per day (Yes = 1, No = 0) Working in awkward postures: stooping for more than 2 hours total per day (Yes = 1, No = 0) Exerting or twisting the torso for more than 2 hours total per day (Yes = 1, No = 0) Forceful exertions: lifting objects weighing more than 11 kg (25 lb) more than 25 times per day (Yes = 1, No = 0) Stress about future income (Yes = 1, No = 0)
2.70
1.29-5.65
.008
2.38
1.37-4.14
.002
3.67
1.88-7.17
Work-Related Musculoskeletal Disorders Among Sugarcane Farmers in Northeastern Thailand Teerasak Phajan, Kessarawan Nilvarangkul, Dariwan Settheetham and Wongsa Laohasiriwong Asia Pac J Public Health published online 21 March 2014 DOI: 10.1177/1010539514528026 The online version of this article can be found at: http://aph.sagepub.com/content/early/2014/03/20/1010539514528026.citation A more recent version of this article was published on - May 13, 2014
Published by: http://www.sagepublications.com
On behalf of:
Asia-Pacific Academic Consortium for Public Health
Additional services and information for Asia-Pacific Journal of Public Health can be found at: Email Alerts: http://aph.sagepub.com/cgi/alerts Subscriptions: http://aph.sagepub.com/subscriptions Reprints: http://www.sagepub.com/journalsReprints.nav Permissions: http://www.sagepub.com/journalsPermissions.nav
Version of Record - May 13, 2014 >> OnlineFirst Version of Record - Mar 21, 2014 What is This?
Downloaded from aph.sagepub.com at PENNSYLVANIA STATE UNIV on May 26, 2014
528026 research-article2014
APHXXX10.1177/1010539514528026Asia-Pacific Journal of Public HealthPhajan et al
Original Article
Work-Related Musculoskeletal Disorders Among Sugarcane Farmers in North-Eastern Thailand
Asia-Pacific Journal of Public Health 1–8 © 2014 APJPH Reprints and permissions: sagepub.com/journalsPermissions.nav DOI: 10.1177/1010539514528026 aph.sagepub.com
Teerasak Phajan1, Kessarawan Nilvarangkul, PhD, REQW1, Dariwan Settheetham, PhD1, and Wongsa Laohasiriwong, PhD1
Abstract This cross-sectional analytical study aimed to identify prevalence and factors associated with work-related musculoskeletal disorders (WMSDs) among sugarcane farmers. Cluster random sampling was used to select 540 sugarcane farmers from 3 provinces in North-Eastern Thailand. Three related questionnaires, plus assessments by 2 expert physiotherapists, were used to check for factors associated with WMSDs and prevalence of WMSDs. Data were analyzed using descriptive statistics and multiple logistic regressions. The results indicated the prevalence of WMSDs among sugarcane farmers in the 7 days before the interview and looking back over the previous 12 months were 82.96% and 88.70%, respectively. Factors significantly associated with reporting WMSDs (P value < .05) during past 12 months were (a) repetitive motions (adjusted odds ratio [OR] = 1.90; 95% confidence interval [CI] = 1.05-3.43), (b) working in awkward postures (adjusted OR = 1.95; 95% CI = 1.01-3.77), (c) forceful exertions (adjusted OR = 2.78; 95% CI = 1.54-5.02), and (d) stress about future income (adjusted OR = 1.80; 95% CI = 1.023.16). Recommendations are made for risk prevention strategies. Keywords musculoskeletal disorders, working postures, repetitive work, forceful exertions, financial stress, sugarcane farmers, Thailand
Introduction Work-related musculoskeletal disorders (WMSDs) are a common health problem among the general working population. In Thailand, there are approximately 274 832 cases of WMSDs per year.1 These disorders raise the cost of workers’ compensation by approximately 11 000 million baht per annum (US$333 million per annum). It should also be noted that the cost of lost time associated with WMSDs is often overlooked and unaccounted for.2 The symptoms of WMSDs are typically stress, sickness, a noticeable decrease in overall physical activity levels, the inability to perform certain other physical activities, decreased working efficiency, and a low quality of life.3-5
1Khon
Kaen University, Khon Kaen, Thailand
Corresponding Author: Kessarawan Nilvarangkul, Faculty of Nursing, Khon Kaen University, Khon Kaen 40002, Thailand. Email: [email protected]
Downloaded from aph.sagepub.com at PENNSYLVANIA STATE UNIV on May 26, 2014
2
Asia-Pacific Journal of Public Health
In Thailand, sugarcane work is seasonal. During the growing period from November until April, the workforce is never less than 600 000 persons.6 Sugarcane farmers are directly involved in the production process and are therefore exposed to most of the associated risk factors. The few existing studies show that sugarcane work is characterized by extreme repetition, forceful movements, continuous body contortions, awkward postures, high workloads, and psychosocial pressures.7,8 However, little research has been carried out to investigate the risk factors associated with WMSDs in North-Eastern Thailand. Moreover, there is a gap in such knowledge because few basic statistics are available on the prevalence of WMSDs among the general working population. This study therefore aimed to identify the prevalence of WMSDs among sugarcane farmers in Thailand and the factors associated with increased morbidity. This article analyses factors associated with risk exposure, drawing on questionnaire data, and discusses strategies for mitigating these risks.
Methods Recruitment of Subjects This study was a cross-sectional analytical survey administered to sugarcane farmers working in North-Eastern Thailand. The required sample size was estimated using a formula for multiple logistic regression to identify relationships between multiple independent variables and a dichotomous dependent variable.9 Cluster random sampling was applied to select 540 sugarcane farmers spread across a study of 3 provinces (Khon Kaen, Nakhon Ratchasima, Udon Thani). See Figure 1. The inclusion criteria for participants was that they engaged in at least one activity ranging from cutting, tightening, applying fertilizer, lifting cane onto loading trucks, weed control, had worked in that activity for at least 1 year, and were between 18 and 59 years old. Potential participants were excluded if they had a preexisting diagnosis of either bone or muscle disease, such as gout, arthritis, rheumatism, osteoporosis, osteoarthritis, myasthenia gravis, immune deficiency, menopausal syndrome, or had received surgery for a bone or muscle disorder. Data were collected between October 25, 2012, and January 15, 2013.
Research Instruments The study used separate questionnaires to assess (a) workers’ perceptions of the importance of the physical, environmental, and psychosocial risk factors that were associated with WMSDs and (b) the extent of pain and disability suffered by those workers. An initial screening questionnaire was also applied to identify subjects for inclusion in the study and to distinguish workers who were actually affected by WMSDs from those experiencing other illnesses. A questionnaire dealing with background demographic data was developed by the researcher, with 3 sections dealing with physical, environmental, and psychosocial risks. This was pretested with 30 sugarcane farmers in Sahatsakhan district, Kalasin province. Reliability was assessed using Cronbach’s α, yielding a score of .84, which was judged acceptable. Six experts commented on the draft questionnaire, and revisions were made to improve its validity. The Standardized Nordic Questionnaire10 measured the respondents’ subjective perceptions of disability and pain and was used alongside the purpose-designed questionnaire on risk factors to examine the relationship between risk exposure and WMSDs. It was chosen because it could identify body region disorders (neck, shoulder, elbow, wrist, upper back, low back, hip, knee, ankle, and foot) experienced in either the past 7 days or the last 12 months. The tool is widely used worldwide and is generally considered to be highly reliable, for example, achieving a reliability of .90.11 In Thailand, it has been calculated that the instrument had a reliability of .80.12
Downloaded from aph.sagepub.com at PENNSYLVANIA STATE UNIV on May 26, 2014
3
Phajan et al
Figure 1. Map of the 3 provinces studied in North-Eastern Thailand.
It was realized that self-reported pain would be affected by respondents’ differential pain tolerance thresholds, which might result in low reporting of WMSDs even where the range of motions could be considered abnormal. Thus, the results of the Nordic Standardized Questionnaire were supplemented by musculoskeletal examinations performed by 2 expert physiotherapists who assessed the range of motions achievable (this term refers to the extent to which a joint or group of muscles can be flexed or extended). Thus, the questionnaire responses were analyzed alongside the forms completed by the 2 expert physiotherapists recording the results of the musculoskeletal examination (mainly relating to range of motion).
Data Analysis After data collection, the data were validated, coded, and analyzed using the statistical application package STATA version 10.0. Descriptive statistics were used to examine the characteristics of sugarcane farmers and the prevalence of WMSDs. Associations between independent variables and WMSDs were analyzed using the χ2 test, and multiple logistic regression analysis was applied to determine the adjusted odds ratio with a 95% confidence interval.
Research Ethics The proposal and the tools were submitted and approval was granted by the Ethics Committee of Khon Kaen University (Reference No. HE 552186).
Downloaded from aph.sagepub.com at PENNSYLVANIA STATE UNIV on May 26, 2014
4
Asia-Pacific Journal of Public Health
Table 1. The Prevalence of WMSDs Among Sugarcane Farmers in the Past 7 Days and the Last 12 Months (n = 540). In the Past 7 Days WMSDs No Yes 1 sitea 2 sites 3 sites 4 sites 5 sites 6 sites 7 sites 8 sites 9 sites
In the Last 12 Months
Number
Prevalence (95% CI)
Number
Prevalence (95% CI)
92 448 115 138 81 50 25 27 7 4 1
17.04 (13.96-20.47) 82.96 (79.52-86.03) 25.67 (22.10-29.64) 30.80 (26.87-34.82) 18.08 (14.98-21.66) 11.16 (8.58-14.07) 5.58 (5.14-5.99) 6.03 (5.61-6.45) 1.56 (1.26-1.89) 0.89 (0.66-1.16) 0.22 (0.11-0.38)
61 479 119 128 83 54 42 23 21 6 3
11.30 (8.75-14.27) 88.70 (85.72- 91.24) 24.84 (21.22-28.68) 26.72 (22.98-30.61) 17.33 (14.30-20.87) 11.27 (8.75-14.27) 8.77 (84.71-90.41) 4.80 (4.367-52.27) 4.38 (3.96-4.81) 1.25 (1.00-1.56) 0.63 (0.43-0.86)
Abbreviations: WMSD, work-related musculoskeletal disorder; CI, confidence interval. aNumber of site, for example, 1 site means a sugarcane farmer has WMSDs at 1 position: neck or hip; 2 sites mean a sugarcane farmer has WMSDs at 2 positions: knee and hip or hip and shoulder.
Results Characteristics of the Study Sample A total of 57.59% of the respondents were females. The average age was 44.75 ± 7.67 years; 95.00% were married, and 62.59% had finished primary education. Respondents had an average body mass index of 24.30 ± 3.79 kg/m2.
Prevalence of Musculoskeletal Disorders in Sugarcane Farmers The majority of respondents perceived they had experienced WMSDs in the past 7 days and in the last 12 months, and the results are given in Table 1. Data for those who had experienced WMSDs in the past 7 days, in the last 12 months, and sickness absences in the last 12 months are given in Figure 2.
Factors Associated With Work-Related Musculoskeletal Disorders Among Sugarcane Farmers Bivariate analysis showed statistically significant associations between WMSDs in last 12 months factors. Bivariate analysis was selected for the multivariate modeling process, and the results are given in Table 2. Multivariate analysis using multiple logistic regression analysis indicated statistically significant associations between suffering WMSDs in last 12 months and several factors (P value < .05), and the results are given in Table 3.
Discussion The prevalence of WMSDs among sugarcane farmers in this study was 88.70% (Table 1). The farmers had WMSDs in their low backs (58.70%), shoulders (42.96%), and wrists (32.22%; Figure 2). This result was higher than other studies related to farmers in Malaysia (58.30%)13 and
Downloaded from aph.sagepub.com at PENNSYLVANIA STATE UNIV on May 26, 2014
5
Phajan et al
Figure 2. The prevalence of WMSDs in the past 7 days, in the past 12 months, and for sickness absences in the last 12 months. Table 2. Unadjusted ORs of Having WMSDs of Sugarcane Farmers and Their 95% CIs for Each Factor (n = 540). Factors
OR
95% CI
P Value
Extending or twisting the wrist repeatedly for more than 2 hours total per day (Yes = 1, No = 0) Repetitive motions: worker repeats the same motion with the neck, shoulder, elbows, wrists, or hand for more than 2 hours total per day (Yes = 1, No = 0) Work that entails prolonged standing for more than 4 hours per day (Yes = 1, No = 0) Exerting or squeezing the hand continuously for more than 2 hours total per day (Yes = 1, No = 0) Working in awkward postures: stooping for more than 2 hours total per day (Yes = 1, No = 0) Exerting or twisting the torso for more than 2 hours total per day (Yes = 1, No = 0) Forceful exertions: lifting objects weighing more than 11 kg (25 lb) more than 25 times per day (Yes = 1, No = 0) Stress about future income (Yes = 1, No = 0)
2.70
1.29-5.65
.008
2.38
1.37-4.14
.002
3.67
1.88-7.17
