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Most studies find strong evidence that motorcycle helmets protect against injury, but a small number of controversial studies have reported a positive association between helmet use and neck injury. The most commonly cited paper is that of Goldstein (1986). Goldstein obtained and reanalyzed data from the Hurt Study, a prospective, on-scene investigation of 900 motorcycle collisions in the city of Los Angeles. The Goldstein results have been adopted by the anti-helmet community to justify resistance to compulsory motorcycle helmet use on the grounds that helmets may cause neck injuries due to their mass. In the current study, we replicated Goldstein's models to understand how he obtained his unexpected results, and we then applied modern statistical methods to estimate the association of motorcycle helmet use with head injury, fatal injury, and neck injury among collision-involved motorcyclists. We found Goldstein's analysis to be critically flawed due to improper data imputation, modeling of extremely sparse data, and misinterpretation of model coefficients. Our new analysis showed that motorcycle helmets were associated with markedly lower risk of head injury (RR 0.40, 95% CI 0.31-0.52) and fatal injury (RR 0.44, 95% CI 0.26-0.74) and with moderately lower but statistically significant risk of neck injury (RR 0.63, 95% CI 0.40-0.99), after controlling for multiple potential confounders., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Objective: The "risk compensation" hypothesis suggests that individuals offset perceived gains in safety by increasing their risk-taking behavior to maintain a stable or "homeostatic" level of risk. If this is true for motorcyclists, then helmet use, which reduces the risk of brain injury and death, may lead helmet users to take more risks when they ride. Thus, increased risk-taking by helmet users should show up as overrepresentation in crashes, and accident reconstruction should reveal risky behaviors in the seconds just before the crash. This article examines data from two separate studies involving the on-scene, in-depth investigation and reconstruction of motorcycle crashes: 900 in Los Angeles (1976-1977) and another 1082 in Thailand (1999-2000)., Methods: Each crash was investigated on scene within minutes of its occurrence by teams of specially trained researchers and later reconstructed in order to identify precrash and crash events, verify helmet use/nonuse, etc. "Exposure" data on helmet use and other readily visible factors were also collected for the population-at-risk by observing riders who passed by each accident scene some time after a crash that had been investigated by the team. In this article, helmeted and unhelmeted accident-involved riders are compared to each other as well as to the population-at-risk., Results: In Thailand, helmeted riders did not differ significantly from unhelmeted riders in alcohol use, precrash speed, being the primary or sole cause of the crash, or unsafe speed or lane positioning for the traffic conditions; they were no more likely to be in a single-vehicle accident, to crash by running off the road, or to lose control. In Los Angeles, drinking riders were half as likely to wear a helmet as nondrinkers. However, when drinkers and nondrinkers were segregated, helmeted riders were no more likely to cause their crash, run stop signs or red lights, commit other traffic code violations, or run off the road. They did not differ in speed or single-vehicle crash rates. In both studies, helmeted riders were underrepresented in crashes compared to helmet use in the population-at-risk, and helmet use was associated with greater distances traveled., Conclusions: The data fail to support the hypothesis that the increased safety provided by motorcycle helmet use is offset by more risk-taking while riding. The only evidence of risk compensation was that helmet use increased with greater amounts of travel.

Objective: To compare the effectiveness of motorcycle helmets seen in prospective on-the-street motorcycle accident investigations. The data are drawn from two detailed, in-depth studies of motorcycle accidents, in which trained investigators collected extensive accident evidence on-scene immediately after the crash. This article compares helmeted and unhelmeted motorcycle riders on a per-accident basis for fatality rates, the rate of serious (AIS > 2) brain injuries among survivors, or an outcome that involved either of the two., Methods: Nine hundred motorcycle crashes in Los Angeles and 969 crashes in Thailand were investigated in detail at the accident scenes, including photos of vehicles, skids, damage, and sometimes the rider. Helmets were collected and injury information was obtained from riders and care providers. This evidence was then used to reconstruct collision events to identify speeds, precrash motions, collision contacts, injury causation, and helmet performance., Results: In both studies, approximately 6% of riders were killed and 20-25% were hospitalized. Overall, unhelmeted riders were two to three times as likely to be killed, and three times as likely to suffer either death or survival with AIS > 2 brain injury. Unhelmeted survivors had three to four times as many AIS > 2 brain injuries as helmeted riders on a per-crash basis. Nearly 100% of riders with AIS > 4 somatic injuries died. Such injuries were 30% of Thailand fatalities and 57% of L.A. fatalities, but only about 2-3% of the overall accident population. Among the 97-98% of riders with AIS < 5 somatic injuries, helmet use could prevent about three-fourths of fatalities and brain injuries., Conclusions: Helmets were extremely effective in preventing brain injury and death in 97% of the accident population in less-than-extreme crashes. Helmet use cannot prevent all fatalities because many of those killed succumb to below-the-neck injuries that a helmet cannot prevent.