ORIGINAL CONTRIBUTION helmet use, motorcycle; motorcycle, trauma
A Prospective Study of the Impact of Helmet Usage on Motorcycle Trauma Study objective: To determine the effect of the use of a motorcycle helmet on reducing the mortality, morbidity, and health care costs resulting from motorcycle crashes. Design: A prospective, multicenter study of all eligible motorcycle crash victims. Setting: The emergency departments of eight medical centers across the state of Illinois, including representatives from urban, rural, teaching, and community facilities. Type of participants: All motorcycle crash victims presenting less than 24 hours after injury for whom helmet information was known. Data were collected from April 1 through October 31, 1988. Measurements and main results: Fifty-eight of 398 patients (14.6%) were helmeted, and 340 (85.4%) were not. The nonhelmeted patients had higher Injury Severity Scores (11.9 vs 7.02), sustained head/neck injuries more frequently (41.7 vs 24.1%), and had lower Glasgow Coma Scores (13.73 vs 14.51). Twenty-five of the 26 fatalities were nonhelmeted patients. By logistic regression, the lack of helmet use was found to be a major risk factor for increased severity of injury, A 23% increase in health care costs was demonstrated for nonhelmeted patients (average charges $7,208 vs $5,852). Conclusion: Helmet use m a y reduce the overall severity of injury and the incidence of head injuries resulting from motorcycle crashes. A trend toward higher health care costs was demonstrated in the nonhelmeted patients. [Kelly P, Sanson T, Strange G, Orsay E: A prospective study of the impact of helmet usage on motorcycle trauma. Ann Emerg Med August 1991;20:852-856.]
INTRODUCTION Motorcycle crashes account for a disproportionate share of deaths and disability resulting from m o t o r vehicle crashes. In Illinois from 1982 through 1987, motorcycle crashes accounted for only 1.7% of all motor vehicle crashes, whereas they accounted for 12.6% of motor vehicle fatalities. During this five-year period, almost 1,000 motorcyclists died in the state. Illinois remains one of only six states that lack mandatory helmet legislation and has the longest interval of these since repeal of its mandatory helmet use law (21 years), t-3 We undertook this prospective study to define the effect of helmet use on the morbidity, mortality, and health care costs resulting from motorcycle crashes. We simultaneously assessed both the injury and the financial impact of motorcycle crashes while evaluating crash variables extensively.
Patrick Kelly, MD Tracy Sanson, MD Gary Strange, MD, FACEP Elizabeth Orsay, MD, FACEP Chicago, Illinois From the Program in Emergency Medicine, University of Illinois, College of Medicine, Chicago. Received for publication May 3, 1990. Revisions received October 12, 1990, and March 22, 1991. Accepted for publication April 27, 1991. Supported by a grant from the Itlinois Department of Transportation. Presented at the Illinois ACEP Scientific Assembly in Chicago, March 1989; the Society for Academic Emergency Medicine Annual Meeting in San Diego, May 1989; and the Sixth World Conference on Emergency and Disaster Medicine in Hong Kong, September 1989. Address for reprints: Patrick Kelly, MD, 118 Wentworth Street, Charleston, South Carolina 29401.
MATERIALS A N D METHODS We conducted a statewide prospective study during the "motorcycle riding season" in Illinois (April 1 through October 31, 1988). The study was conducted at eight centers in four counties representing urban, suburban, and rural settings. To ensure consistency among the centers, members of the research team were assembled before data collection to review the study questionnaire, inclusion criteria, and calculation of Injury Severity Scores (ISS). Patients eligible for inclusion were those who were passengers or drivers involved in motorcycle crashes occurring less than 24 hours before presentation and
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HELMET USAGE Kelly et al
for w h o m h e l m e t i n f o r m a t i o n was k n o w n . I n f o r m a t i o n was o b t a i n e d from the patient, the family, or paramedic or police reports. Only motorcycles with an engine size of 150 cc or more were included, thus excluding m o p e d s and dirt bikes. To enhance enrollment, a financial incentive was awarded to each center for each eligible patient enrolled. County coroners were also contacted to obtain information regarding motorcycle fatalities taken directly to the morgue. On presentation to the emergency department, the examining physician recorded helmet information, time of accident, road c o n d i t i o n s , m e c h a nism of injury (vehicle to vehicle, vehicle to fixed object, overturn, or other), speed of travel, posted speed limit, position on m o t o r c y c l e (passenger versus operator), possession of valid motorcycle license, disposition from the ED, and modified C h a m pion Trauma Score. Both estimated speed of travel (per the patient or a police officer) and posted speeds were obtained. Later, a member of the research team recorded injury data, alcohol level (if measured), ISS, and financial data, including total charges, number of hospital days, and method of payment. Final disposition from the hospital was included as was the name of the receiving facility if the patient was transferred. F i n a n c i a l d a t a i n c l u d e d ED charges, inpatient charges, and initial r e h a b i l i t a t i o n charges. L o n g - t e r m charges for o n g o i n g r e h a b i l i t a t i o n were not assessed. Physician charges for inpatient and rehabilitation services were not included because these charges were not available to the researchers at all of the participating centers. For transferred patients, total charges and lengths of stay were recorded. Actual ED and hospital charges were used to estimate health care costs in these analyses. The Stat Pac Gold Statistical Analysis Package was used for data analysis. A P value < .05 was considered statistically significant.
RESULTS Four hundred two questionnaires were completed; 398 patients were entered into the study. Four patients were excluded: one due to lack of helmet information, two because of cycle size of less than 150 cc, and one 56/853
TABLE 1. Descriptive data for h e l m e t e d vs n o n h e l m e t e d patients Characteristic
Time of Accident (%) AM PM
Road Surface (%) Dry Wet
Type of Roadway (%) Rural City street Other Interstate
18.5 64.8 5.6 11.1
9,5 73.7 10.7 6.1
Estimated Speed of Travel in mph (%) 11 25 26 - 40 41 - 55 > 55
26.8 41,1 25.0 7.1
40.6 40.6 10.5 8.3
Age (yr) Patient Posilion (%) Operator Passenger Sex (%) Female Male
Possession of Valid Motorcycle License (%)
Ambulance Transport (%) Patient Disposition From ED (%) Admitted Discharged
Positive Blood Alcohol (79 Tested) (%)
Payment Status (%) Third-party gay Uninsured
who presented more than 24 hours after the crash. Contact with county coroners resulted in two scene death entries into the study. Of the 398 patients, 58 (14.6%) were wearing helmets, and 340 (85.4%) w e r e not. There were 338 operators and 60 passengers; 88.9% were male. Overall, the majority of crashes occurred during the evening hours, on city streets, and u n d e r dry conditions. There were no significant diff e r e n c e s b e t w e e n the t w o g r o u p s with regard to age, sex, time of day that the crash occurred, light conditions, type of roadway, or m e c h a n i s m of i n j u r y (Table 1). H o w e v e r , helmeted motorcyclists were more likely to have a valid motorcycle license, were more frequently involved in crashes while traveling on wet surfaces, and were less likely to have a Annals of Emergency Medicine
p o s i t i v e blood a l c o h o l level t h a n w e r e n o n h e l m e t e d c y c l i s t s . Estimated speeds of travel were similar for the groups, except that there were more helmeted riders in the 41 to 55 m p h category. However, when comparing estimated speed of travel with posted speed limit: for each group, the n o n h e l m e t e d riders e x c e e d e d t h e speed limit more frequently, particularly in the highest speed range. Injury data were calculated using the Abbreviated Injury Scale (AIS) and the ISS. 4-6 The mean ISS for helmeted motorcyclists was 7.02 + 1.44 (_+ SEM) vs 11.12 _+ .94 for n o n helmeted motorcyclists, representing a 36% increase in the nonhelmeted group (P = .038)(Figure 1). Considering the m o r e s e v e r e l y injured patients (ISS > 15), there was a trend toward lack of helmet use, with non20:8 August 1991
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FIGURE 1. Injury Severity Score. 18v
FIGURE 2. Incidence of injury in each AIS body region, helmet versus no helmet.
NH 11.189 12
P = ,0380 (one-t)
AIS P ~ 0214 Calegory Hea6rNeck
P = 4226 Face
P = 7417 Thorax
P = 0848 Abdomen and Pelvic Contents
P = 0415 Extremity and Pelvic eir61e
P - 0054 E~lernal
TABLE 2. Predictors of higher injury severity Variable
Increase in R2.
.072 .051 .021 .017
,001 .001 .005 .019
Estimatedspeed of travel Mechanismof injury Helmet status Age *R 2 equal In c o e f f i c i e n t
of m u l t i p l ~
hehneted cyclists having a twofold incidence of ISS of more than 15 compared with h e l m e t e d cyclists (17.8% vs 8.6%, P = .123). This translates to an odds ratio of 2.23 for an increased risk of a severe injury in the nonhelmeted group. There were 26 fatalities in the study, 25 of which were in the nonhelmeted group (P = .196). Logistic regression was undertaken to assess those variables associated with increasing ISS. Factors assessed included patient sex, age, estimated speed of travel, mechanism of injury, road surface conditions, helmet sta20:8 August 1991
tus, possession of a valid motorcycle license, and positive blood alcohol level. The significant predictors of higher ISS, in decreasing order of contribution, were estimated speed of travel, mechanism of injury, helmet status, and age (Table 2). These four factors contribute 16% (the sum of the increase of R 2 for each variable) to the overall risk of severe injury. A comparison was then made of these risk factors between helmeted and n o n h e l m e t e d cyclists. Interestingly, there were no differences regarding m e c h a n i s m of injury, estimated speeds of travel, and age. Lack of motorcycle helmet use was, therefore, a significant predictor of higher ISS. Three AIS body regions were found to have statistically different incid e n c e s of i n j u r y b e t w e e n n o n h e l m e t e d and h e l m e t e d cyclists. Head/neck and external injuries (eg, lacerations, contusions, abrasions) were more frequent and extremity injuries were less frequent in nonhelmeted cyclists (Figure 2). The incidence of head/neck injuries in the nonhelmeted group was almost twice that of the helmeted group. Within this category, there were three times as m a n y head injuries in the nonhelmeted group (12.1% vs 32.6%, P < .0001). Furthermore, nonhelmeted cyclists had l o w e r G l a s g o w C o m a Scores than helmeted motorcyclists (13.73 vs 14.51, respectively; P = .05). In patients with a severe head injury (AIS /> 3), there was an approximately threefold greater incidence in the n o n h e l m e t e d group (3.4% vs 10.6%), although statistical significance was not reached. There was no significant difference between the two groups for the incidence of overall neck injuries (10.3% helmeted vs 13.5% nonhelmeted) or neck injuries with neurological sequelae (3.6% helmeted vs 0.9% nonhelmeted). The average charges of care for helm e t e d m o t o r c y c l i s t s i n v o l v e d in crashes was $5,852 + 1,527 vs $7,208 -+ 998 for n o n h e l m e t e d cyclists, a 23% increase in health care costs (P = .30). There were no significant differences between the groups regardAnnals of Emergency Medicine
ing hospital admission rate, length of stay, and need of a long-term care facility. Nonhelmeted patients tended to be transported by ambulance more frequently (63.4% vs 46.4%, P = .078). Analysis of patient payor status revealed a higher incidence of selfpay status in the nonhelmeted group, although this did not reach statistical significance (54.6% vs 44.2%, P = .210). The total health care charges for all patients studied was more than $2.7 million, and these crashes resulted in more than 2,000 inpatient days. By scattergram analysis, patients most severely injured (ISS > i5), had the longest and most costly stays, and these tended to be nonhelmeted patients (P = .12). DISCUSSION In this study, we found that helmet use reduced the overall incidence and severity of injury in m o t o r c y c l e crashes in Illinois and reduced the incidence of injuries in the AIS category of head/neck. A trend toward reducing health care costs also was found. Our data reconfirm the disturbingly low rate of helmet use found in the reports of other states that lack m a n d a t o r y h e l m e t use laws. 7-13 States that have mandatory helmet use laws report an 80% to 99% compliance rate, attesting to the effectiveness of such legislation in convincing motorcyclists to wear helmets.m, t3-1s Further effect of these mandatory helmet laws was demonstrated when the Highway Safety Act of 1976 lifted the penalty for noncompliance with mandatory safety legislation; 27 states repealed or revised their mandatory helmet laws, resulting in a 25% to 46% increase in m o t o r c y c l e d e a t h s n a t i o n wide. 12,16 This was specifically docum e n t e d by nine states (Colorado, Kansas,; Oklahoma, South Dakota, Indiana, Rhode Island, Arizona, Minnesota, and South Carolina), all of which showed significant increases in both injury and fatality rates after repeal of their m a n d a t o r y h e l m e t law.] 1,17-22
The increased incidence of injuries in the head/neck AIS category in the nonhelmeted motorcyclists has been shown previously in m a n y studies. 7,s,17,23 We looked further at each body region component of this category and found differences of note. We demonstrated a higher inci854/57
HELMET USAGE Kelly et al
dence of severe head injuries in the n o n h e l m e t e d g r o u p , w h i c h is in a g r e e m e n t w i t h B a c h u l i s et al and Luna et al.7,17 The odds ratio that we calculated for severe injury (ISS > 15) associated w i t h l a c k of h e l m e t u s e a p p r o x i m a t e s that f o u n d in N o r t h D a k o t a (3.2) after repeal of its m a n d a t o r y helm e t law for those over age 18.s We f o u n d no s i g n i f i c a n t d i f f e r e n c e bet w e e n the groups in the n u m b e r or s e v e r i t y of n e c k i n j u r i e s , h o w e v e r , c o u n t e r i n g t h e c l a i m of i n c r e a s e d neck injuries w i t h h e l m e t use m a d e by some h e l m e t opponents.12,14, 24 It is of interest to note the lower incid e n c e of e x t r e m i t y i n j u r i e s in t h e n o n h e l m e t e d group. This finding was also d o c u m e n t e d by Bachulis et al, 7 and we believe that it reflects inadeq u a t e d o c u m e n t a t i o n of o c c u l t ext r e m i t y i n j u r i e s in t h o s e p a t i e n t s w h o die, m o s t of w h o m a r e n o n h e l m e t e d (96% in o u r study). T h e d i s p r o p o r t i o n a t e n u m b e r of f a c i a l and scalp l a c e r a t i o n s s u s t a i n e d b y n o n h e l m e t e d c y c l i s t s is t h o u g h t to a c c o u n t for the higher i n c i d e n c e of " e x t e r n a l " i n j u r i e s s e e n in t h a t group. M a n y studies have assessed financial s t a t i s t i c s r e l a t e d to m o t o r c y c l e trauma.8,23, 25-2s These statistics emphasize the significant e c o n o m i c impact of m o t o r c y c l e injuries and the financial burden that the taxpayer frequently assumes. Furthermore, either through direct comparisons, c o s t - b e n e f i t a n a l y s e s , or i m p l i e d c o m p a r i s o n based on prior studies, h e l m e t e d patients have been shown to have lower h e a l t h care costs and fewer indirect losses and to be more likely to have medical insurance. 13~26,28 In our prospective study, we were a l s o a b l e to d e m o n s t r a t e l o w e r health care costs for injuries suffered by h e l m e t e d cyclists, w h o were m o r e likely to be insured as well, but the differences proved n o t to be statistically significant. We p o s t u l a t e that a larger s a m p l e size w i t h a larger n u m b e r of patients in the h e l m e t e d group w o u l d s h o w s t a t i s t i c a l l y significant cost variance. F u r t h e r m o r e , this study addressed only acute health care charges. We m a d e no estimates of the indirect costs for the 25 n o n h e l m e t e d f a t a l i t i e s or the ongoing costs for n o n h e l m e t e d rehabilitation patients. Had such indirect costs such as lost p r o d u c t i v i t y , d i s a b i l i t y 58/855
c o m p e n s a t i o n , a n d so on b e e n included, then a m u c h larger difference m i g h t have been demonstrated. The initial power analysis we cond u c t e d was based on a s s u m i n g two n o n h e l m e t e d r i d e r s for e v e r y h e l m e t e d rider. A c t u a l l y , we h a d a 6:1 r a t i o of n o n h e l m e t e d to h e l m e t e d cyclists, resulting in a m u c h smaller (58) h e l m e t e d group. This v a r i a n c e c o n t r i b u t e s to t h e p o s s i b i l i t y of a type II (~) error in our financial data and in some of the injury data (eg, fatality rate only approaching statistical significance). F u r t h e r s t u d y s h o r t c o m i n g s inc l u d e a l a c k of d e t a i l e d c r a s h s i t e a n a l y s e s and further e l a b o r a t i o n of m o t o r c y c l e r i d e r b e h a v i o r . It m a y well be that cyclists who wear helm e t s are safer operators t h a n those w h o do not. However, m e a s u r e m e n t of such factors as safety and behavior are difficult if not impossible to assess. We e v a l u a t e d o n l y t h o s e variables that could be objectively identified and assessed. CONCLUSION We h a v e s h o w n t h a t m o t o r c y c l e h e l m e t use m a y significantly reduce overall injury severity and the incidence of head injuries. A m o n g those crash variables that predict the m o s t severely injured patients, the lack of h e l m e t use is a k e y c o n t r i b u t o r to increasing injury severity. A trend toward higher direct h e a l t h care costs and a greater incidence of patients req u i r i n g l o n g e r and m o r e e x p e n s i v e hospital stays were also demons t r a t e d in n o n h e l m e t e d m o t o r c y clists.
The authors extend their gratitude to the following people for their support in data collection: Denise Fligner, MD (Christ Hospital, Oak Lawn, Illinois); Edward Sloan, MD, Robert Zalenski, MD (Cook County Hospital, Chicago); Otto Metzmaker, MD (St John's Hospital, Springfield, Illinois); Jerry Thurman, DO (Carbondale Memorial Hospital/Marion Hospital, Carbondale, Illinois); Arthur Proust, MD (Rockford Memorial Hospital, Rockford, Illinois); and the University of Illinois Emergency Medicine Residents (Mercy Hospital and Medical Center, Chicagol Lutheran General Hospital, Park Ridge, Illinois; and Illinois Masonic Medical Center, Chicago). Their thanks also go to Karlene Montgomery and Elizabeth Springer for their assistance in manuscript preparation. Statistical analysis was Annals of Emergency Medicine
conducted by Elizabeth Gordon, PhD, and Bryan Coyle, MA, Department of Research and Education, Lutheran General Hospital, Park Ridge, Illinois.
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26. Hartunian NS, Smart CN, Willemain TR, et al: The
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motorcycle hehnet laws. Am J Public Health 1980;70: 586-592. 28. Rivara F, Dicker B, Bergman A, et al: The public cost of motorcycle trauma, lAMA 1988;260:221-223.