1 Journal of Surgical Research 158, 1 5 (2010) doi: /j.jss ASSOCIATION FOR ACADEMIC SURGERY Motorcycle Helmets Save Lives, But Not Limbs: A National Trauma Data Bank Analysis of Functional Outcomes After Motorcycle Crash 1 Joseph G. Crompton, M.D.,*,2 Tolulope Oyetunji, M.D., M.P.H., Kent A. Stevens, M.D., M.P.H.,* David T. Efron, M.D.,* Elliott R. Haut, M.D.,* and Adil H. Haider, M.D., M.P.H.* *Department of Surgery, The Johns Hopkins University School of Medicine, Baltimore, Maryland; and Department of Surgery, Howard University College of Medicine, Washington, D.C Submitted for publication January 10, 2009 Background. The incidence of motorcycle fatalities over the last 10 y has nearly doubled. There is considerable evidence that motorcycle helmets save lives, but there are little data regarding the impact that helmets have on functional outcomes after a motorcycle crash. The objective of this study was to determine the difference between helmeted and non-helmeted motorcyclists in the odds of developing a functional deficit at discharge in three domains: speech, locomotion, and feeding. Methods. Reviewed cases in the National Trauma Databank v7.0 involved in motorcycle collisions. Multiple logistic regression was used to analyze the effect of helmets on mortality and functional outcomes, adjusting for age, race, gender, insurance status, anatomic and physiologic injury severity, and head injury. Results. The adjusted odds of mortality (0.75; 95% CI ) and functional deficits in speech (0.82; 95% CI ), locomotion (1.19; 95% CI ), and feeding ( % CI ) among helmeted riders was compared with non-helmeted motorcyclists with equivalent injuries. Conclusion. motorcyclists are less likely to die and develop a deficit in speech after a motorcycle collision. These data support that motorcycle helmets are important in preventing functional deficits related to head injury. Ó 2010 Elsevier Inc. All rights reserved. 1 This research was presented as a quick shot oral poster at the annual meeting of the Association for Academic Surgery, February 3, 2009, Fort Meyers, Florida. 2 To whom correspondence and reprint requests should be addressed at, Trauma Outcomes Research Group, Department of Surgery, Division of Acute Care Surgery, Johns Hopkins School of Medicine, 600 N. Wolfe Street, Carnegie 683, Baltimore, MD Key Words: motorcycle helmet; functional outcomes; speech deficit; locomotion deficit; feeding deficit; National Trauma Data Bank; trauma. INTRODUCTION According to the National Highway Traffic Safety Administration (NHTSA), 4810 motorcyclists died and nearly 88,000 were injured in 2006 . The incidence of motorcycle fatalities has risen for the last 10 y, and motorcycle fatalities now represent nearly one in eight motor vehicle deaths. It is estimated that per mile travelled in 2006, a motorcyclist was roughly 37% more likely to die in a collision than a passenger in an automobile . There is considerable evidence that motorcycle helmets save lives. A Cochrane review concluded that helmets reduce the risk of death and head injury in riders who crash , and NHTSA estimates that a non-helmeted rider is 40% more likely to incur a fatal head injury, and 15% more likely to suffer from a nonfatal injury than a helmeted motorcyclist . Although there are definitive data that helmets reduce mortality, there is little evidence regarding the impact that helmets have on functional outcomes after a motorcycle crash. Functional deficits in speech, locomotion, and feeding represent significant morbidity associated with motorcycle collisions, and potentially result in long-term medical expenditures and years of potential productivity lost. In a study of 94 patients, Holtz and colleagues investigated several outcomes 1 y postinjury, including return-to-work, but to our knowledge, there are no previous studies using a large database /10 $36.00 Ó 2010 Elsevier Inc. All rights reserved.
2 2 JOURNAL OF SURGICAL RESEARCH: VOL. 158, NO. 1, JANUARY 2010 that have analyzed the impact of motorcycle helmets on functional outcomes . This study investigates whether helmets reduce the likelihood of developing a functional deficit in speech, locomotion, and feeding after a motorcycle crash. It will also determine if motorcyclists who do not wear a helmet are more likely to die than their helmeted counterparts with equivalent injury. METHODS This was a retrospective analysis of all registered cases of motorcycle collision in the National Trauma Data Bank (NTDB ver. 7.0) between 2002 and The NTDB is a convenience sample and is managed by the American College of Surgeons. Data is voluntarily reported from over 700 U.S. trauma centers and hospitals that care for trauma patients, making it the largest registry trauma data ever assembled. Detailed information on the NTDB data collection procedures have been published elsewhere . This study was reviewed by the Johns Hopkins University School of Medicine Institutional Review Board and approved for exempt status. Cases were identified through an electronic search of all International Classification of Diseases (ver. 9) external cause of injury codes for motorcyclist-related collisions in the NTDB . Motorcycle riders and any passengers on the motorcycle who were 18 y of age or older were included (Fig. 1). Demographic data, such as age, gender, race, and insurance status were tabulated for helmeted and non-helmeted motorcyclists. Injury severity data, such as mean injury severity score, presence of shock (systolic blood pressure < 90 mm Hg), and severe head injury were also tabulated. Severe head injury was defined as an abbreviated injury scale (AIS) score > 3 in the region of the head . Presence of severe extremity injury was also tabulated and defined as an AIS > 3 in the extremity region. A comparison between helmeted and non-helmeted riders involved in a motorcycle collision was undertaken. The primary outcome measures were death, presence or absence of a functional deficit in feeding, expression, or locomotion at discharge from hospital. Functional outcomes were measured using a modification of the functional independence measure (FIM) score in the three domains. Each domain had a FIM score range from 1 to 4 (1 ¼ poorest function/completely dependent; 4 ¼ normal function/no dependence). Patient outcomes were categorized as either no deficit (FIM ¼ 4) or presence of deficit (FIM < 4) in each of the three domains. The FIM is a widely validated and accepted scale to measure the functional abilities of patients undergoing rehabilitation and is described in other publications . As data reporting to the NTDB is voluntary, several hospitals did not systematically report any functional outcome data. For this reason, only patients with complete functional outcome data were analyzed in this part of the study. We calculated the proportion of helmet use among those with functional deficits, and multiple logistic regression was also used to analyze the independent effect of helmet use on mortality and functional outcomes. Only cases with complete data for all the following covariates were included in the adjusted analysis: age, gender, race, both anatomic and physiologic injury severity, severe head and extremity injury, and insurance status. To adequately adjust for injury severity, we used the presence or absence of shock to measure the degree of physiologic injury. We employed the injury severity score (ISS) to quantify the extent of anatomic injury in each patient . As our outcome measures included functional parameters, we further adjusted patients for the presence of severe head injury and extremity injury using the AIS, which has been shown to be a predictor of trauma outcomes . Patient demographics, including race, age, and gender, were also included in the regression to control for differences within these 1.8 million patients in NTDB Exclude all causes of injury not related to motorcycle collision 69,396 adults (age 18 years) involved in motorcycle collision Exclude cases without data regarding helmet use 44,847 adults involved in motorcycle collision with completed helmet data Motorcyclists n=34,829 motorcyclists n=10,018 FIG. 1. Patient Selection in the National Trauma Data Bank (NTDB).
3 CROMPTON ET AL.: ANALYSIS OF FUNCTIONAL OUTCOMES AFTER MOTORCYLE CRASH 3 categories. We included race and gender because evidence demonstrates gender and racial disparities in medical treatment and outcomes following trauma [11, 12]. Finally, insurance status (uninsured, commercial insurance, government insurance) was included to control for differences in outcomes based on insurance status . Student s t-test was employed to compare continuous variables, and c 2 was used to compare categorical variables for bivariate analysis. A multiple logistic regression was undertaken while adjusting for differences in the above-mentioned covariates to analyze the independent effect of helmets on both mortality and functional deficits among motorcyclists in a collision. All data analysis was carried out using STATA ver. 10 . RESULTS Between 2003 and 2006, 1,862,348 patient cases were entered into the National Trauma Data Bank (NTDB). Of these patients approximately 4% (n ¼ 69,396) were involved in motorcycle collisions. Crude mortality for all MCC patients was 4.2%, and approximately 54% of riders involved in MCC were reported to wear a helmet. Demographic information of the helmeted and non-helmeted riders is presented in Table 1, and characterization of injury severity is presented in Table 2. riders were slightly older, consisted of a greater proportion of men, and had less insurance coverage than helmeted riders. motorcyclists had a greater prevalence of severe head injury, shock, and were more likely to die than helmeted riders. After adjusting for patient demographics and injury severity with the covariates discussed above, the adjusted odds of mortality among helmeted riders was 0.75 (95% CI ) compared with non-helmeted motorcyclists with equivalent injuries. Functional deficit data was not reported by approximately 30% of hospitals in the NTDB, accounting for roughly 40% of patients in our sample yielding a sample size of over 20,000 cases for the subsequent functional outcomes analysis. The proportion of patients who developed unadjusted deficits in speech, locomotion, and feeding by helmet use are presented in Table 3, and show that helmeted riders have fewer deficits in speech than non-helmeted riders. The adjusted odds of developing a deficit in speech among helmeted motorcyclists was 0.82 (95% CI ) compared with non-helmeted riders, suggesting that helmeted riders involved in a MCC had an 18% less chance of developing a speech deficit compared with non-helmeted riders with similar injuries (Fig. 2). It also shows that helmeted riders were more likely to develop a locomotion deficit compared with their nonhelmeted counterparts. To determine whether a locomotion deficit was more likely due to a traumatic brain injury or extremity injury, we analyzed the population of riders with TABLE 1 Demographic Data of and Non- Riders Involved in a Motorcycle Collision in the National Trauma Data Bank (n ¼ 34,829) locomotion deficits and found that 89.9%* had an extremity injury, and 10.9% (P ¼ 0.771) had a severe head injury. The adjusted odds of developing a locomotion deficit after an extremity injury were 7.06 (95% CI ) compared with motorcyclists without an extremity injury. DISCUSSION (n ¼ 10,018) Male* (%) Race* White (%) non-white (%) Age* (mean) Insured patients* (%) This study demonstrates that helmeted motorcyclists involved in a motorcycle collision were 18% less likely to develop a speech deficit compared with non-helmeted riders with similar injuries. It also shows that helmets reduce mortality among those involved in a motorcycle collision. Use of motorcycle helmets was not, however, associated with a significant reduction in the functional deficits of locomotion and feeding. The finding in this analysis that helmeted riders are 25% less likely to die than similarly-injured nonhelmeted motorcyclists is consistent with previous studies that have shown that helmets reduce head injury and mortality after a motorcycle crash. The National Highway Traffic Safety Administration (NHTSA) estimates that helmets reduce mortality after MCC by as much as 37% . Hurt and colleagues concluded in a retrospective analysis of 3600 traffic reports TABLE 2 Mortality and Injury Severity Characteristics Among and Non- Motorcyclists in the National Trauma Data Bank (n ¼ 34,829) (n ¼ 10,018) Shock* (SPB 90 mm Hg) (%) ISS* (mean) Severe head injury* (AIS 3), (%) Severe extremity injury* (AIS 3), (%) Mortality*, crude (%)
4 4 JOURNAL OF SURGICAL RESEARCH: VOL. 158, NO. 1, JANUARY 2010 TABLE 3 Proportion of Patients with Unadjusted Functional Deficits in and Non- Riders Involved in a Motorcycle Collision in the National Trauma Data Bank (n ¼ 17,207) % (n ¼ 5532) % Speech* Locomotion* Feeding* that helmets are the single most important factor in surviving motorcycle crashes . This survival benefit, evident in this study, is likely an underestimate due to survival bias because we did not account for non-helmeted riders who died at the scene. The mechanism by which helmets reduce the likelihood of developing a speech deficit is most likely a result of the effect of helmets in reducing severe head injury after MCC. This study showed that 20% of nonhelmeted riders had severe head injury, compared to only 9% of helmeted riders. These results validate earlier studies that show helmets protect against head and brain injuries in MCC [16 18]. The Crash Outcome Data Evaluation System (CODES) study, for example, found that non-helmeted motorcyclists involved in crashes were three times more likely to suffer brain injuries than their helmeted counterparts . With regard to the functional outcome of feeding, it was expected that the greater prevalence of traumatic brain injury among non-helmeted riders would also result in greater functional deficits of feeding in nonhelmeted riders. Although there was a trend toward a protective effect of helmets, there was no statistically significant difference in feeding outcome between helmeted and non-helmeted riders found in this analysis. Further studies with a larger sample size may strengthen this association of the protective effect of helmets on feeding outcomes. It may also be that the cause of feeding deficits among motorcyclists is more often facial injuries as opposed to traumatic brain injury, and according to a Cochrane review , there is insufficient evidence regarding the protective effect of helmets on facial injuries. The increased adjusted odds of developing a locomotion deficit with helmet use are most-likely due to an increased survival of severely-injured patients with a concomitant extremity injury. This is supported by the finding that among those with deficits of locomotion, 90% had an extremity injury, and only 11% had a severe head injury. These data suggest that the locomotion deficit was more commonly due to the extremity injury and not an inability to ambulate because of a neurological deficit resulting from a traumatic brain injury. This is further supported by the finding that a motorcyclist with an extremity injury is over 7 times more likely to develop a deficit in walking than those without an extremity injury. The present study is an important contribution to the literature investigating the effect of helmets on the morbidity and mortality associated with motorcycle collisions because it not only demonstrates that helmets reduce the likelihood of developing a long-term deficit in speech, but also confirms the results of earlier studies that have shown a reduction in mortality among motorcyclists wearing a helmet. The legally-mandated use of helmets is currently a highly-debated topic in the context of the repeal of the universal helmet laws in several states. There is compelling evidence to suggest that outcomes such as mortality after MCC have increased in states that have repealed the law because fewer riders are wearing helmets than previously [20 22]. In this analysis, we focused on an outcome that has previously received little attention in the literature on motorcycle helmets. The passage of helmet use legislation demands reliable studies focused on all outcomes to ensure that legislative decisions are based on the best available data regarding the impact of helmets on injury and death associated with motorcycle collisions. There are some limitations to this study, including the standard issue of missing clinical data in trauma FIG. 2. Adjusted odds of developing functional deficit among helmeted motorcyclists compared to non-helmeted riders involved in a motorcycle collision in the National Trauma Data Bank. n¼22,739.
5 CROMPTON ET AL.: ANALYSIS OF FUNCTIONAL OUTCOMES AFTER MOTORCYLE CRASH 5 registries. Systematic non-reporting of data from a large number of hospitals participating in the NTDB has been described elsewhere . In this analysis, there were a significant number of hospitals that did not report functional outcome data. Even so, among the large number of patients meeting inclusion criteria in the NTDB, just over half were suitable for analysis of functional outcomes. Data was also not available for potential confounders, such as severity of crash, involvement of other vehicles, weather, and time of day, motorcycle speed, and alcohol consumption that are often associated with crash fatalities and injury [24, 25]. The type of helmet and motorcycle were also not considered in the analysis. In addition, we were lacking information on several key potential confounders, including patient comorbidities, location of death (e.g., emergency department, operating room, intensive care unit), and medical or surgical therapies implemented, such as the administration of vasoactive agents or blood products. Despite these limitations, the strengths of this study include a large sample size of over 69,000 motorcyclists. To our knowledge, this is the largest multi-institution retrospective review of functional outcomes in speech, feeding, and locomotion after a motorcycle collision. The analysis also adjusted for potential confounders, including race, age, gender, insurance status, anatomic and physiologic injury severity, and severe head injury. The finding that helmeted motorcyclists are less likely to die and suffer from functional deficits after a collision suggests that motorcycle helmets are important in preventing functional deficits related to head injury, and reenactment of the universal helmet law should be considered, to reduce the morbidity and mortality associated with motorcycle crashes. ACKNOWLEDGMENTS The authors acknowledge support for this work by Johns Hopkins School of Medicine and Johns Hopkins Department of Surgery. REFERENCES 1. NHTSA. Recent Trends in Fatal Motorcycle Crashes: An Update. DOT HS Technical Report. Washington, DC: National Highway Traffic Safety Administration, NHTSA. Motorcycle Helmet Use Laws. DOT HS W. Washington, DC: National Highway Traffic Safety Administration, Liu BC, Ivers R, Norton R, et al. Helmets for preventing injury in motorcycle riders. Cochrane Database Syst Rev 2004;(2). CD Holtz GA, Cohn SM, Mishkin D, et al. Outcome of motorcycle riders at one year post-injury. Traffic Inj Prev 2004;5: Professional ICD-9-CM Manual for Hospitals, Ingenix USA Committee on Trauma, American College of Surgeons. NTDB Version 7.1. Chicago, IL The content reproduced from the NTDB remains the full and exclusive copyrighted property of the American College of Surgeons. The American College of Surgeons is not responsible for any claims arising from works based on the original data, text, tables, or figures. 7. Association for the Advancement of Automotive Medicine. The Abbreviated Injury Scale; 1985 and 1990 revisions. Des Plaines, IL. 8. Guide for the Uniform Data Set for Medical Rehabilitation (Including the FIM Instrument), Version 5.1. Buffalo, NY: State University of New York at Buffalo, Baker SP, O Neill B. The injury severity score: An update. J Trauma 1976;16: Haider AH, Chang DC, Haut ER, et al. Mechanism of injury predicts patient mortality and impairment after blunt trauma. J Surg Res 2008 May Sperry JL. Minei JP Gender dimorphism following injury: Making the connection from bench to bedside. J Leukoc Biol 2008;83:499. Epub 2007 Sep 25 Review. 12. Haider AH, Efron DT, Haut ER, et al. Mortality in adolescent girls versusboys following traumatic shock: An analysis of the National Pediatric Trauma Registry. Arch Surg 2007;142:875. discussion Haider AH, Chang DC, Efron DT, et al. Race and insurance status as risk factors for trauma mortality: Not all black and white. Arch Surg 2008 (in press). National Trauma Data Bank (NTDB version 7.0). 14. StataCorp. Stata Statistical Software: Release 10. College Station, TX: StataCorp LP, Hurt HH, Ouellet JV, Thom DR. Motorcycle Accident Cause Factors and Identification of Countermeasures, Volume 1: Technical Report, Traffic Safety Center, University of Southern California, Los Angeles. 16. Houston DJ, Richardson LE. Motorcyclist fatality rates and mandatory helmet-use laws. Accid Anal Prev 2008;40:200. Epub 2007 Jun Sarkar S, Peek C, Kraus JF. Fatal injuries in motorcycle riders according to helmet use. J Trauma 1995;38: Kasantikul V, Ouellet JV, Smith T. Head and neck injuries in fatal motorcycle collisions as determined by detailed autopsy. Traffic Inj Prev 2003;4: Johnson S, Walker J. The crash outcome data evaluation system (CODES) NHTSA Technical Report. Washington DC: Research and Development, National Highway Traffic Safety Administration; 1996 Jan. Report No: DOT HS 20. Proscia N, Sullivan T, Cuff S, et al. The effects of motorcycle helmet use between hospitals in states with and without a mandatory helmet law. Conn Med 2002;66:195. Erratum in. Conn Med 2002;66: Bledsoe GH, Li G. Trends in Arkansas motorcycle trauma after helmet law repeal. South Med J 2005;98: Mertz KJ, Weiss HB. Changes in motorcycle-related head injury deaths, hospitalizations, and hospital charges following repeal of Pennsylvania s mandatory motorcycle helmet law. Am J Public Health 2008;98: Kardooni S, Haut ER, Chang DC, et al. Hazards of benchmarking complications with the National Trauma Data Bank: Numerators in search of denominators. J Trauma 2008;64:273. discussion Sauter C, Zhu S, Allen S, Hargarten S, Layde PM. Increased risk of death or disability in unhelmeted Wisconsin motorcyclists. WMJ 2005;104: Zambon F, Hasselberg M. Factors affecting the severity of injuries among young motorcyclists A Swedish nationwide cohort study. Traffic Inj Prev 2006;7:143.