Motorcycle Helmet Effect on a Per-Crash Basis in the Thailand and Hurt Studies

The data reported here are drawn from two detailed, in-depth studies of motorcycle accidents in which trained investigators collected extensive evidence on-scene immediately after the crash. This paper compares helmeted and unhelmeted motorcycle riders on a per-accident basis for fatality rates, for the frequency of serious (AIS>2) brain injuries among survivors or for what is referred to here a “disastrous outcome” involving either one of the two results. Nine hundred motorcycle crashes in Los Angeles and 969 crashes in Thailand involving 1,082 riders were investigated in detail at the accident scene, 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. In both studies, approximately 20-25% of riders were hospitalized and about 6% were killed. Overall, unhelmeted riders were 2-3 times as likely to be killed, and three times as likely to suffer a “disastrous outcome.” Unhelmeted survivors had 3-4 times as many AIS>2 brain injuries as helmeted riders on a per-crash basis. Unhelmeted riders consistently fared worse than helmeted riders, even when alcohol use was taken into account. Nearly 100% of riders with AIS>4 injuries below the neck died. Crashes that produce such critical injuries are therefore considered to be nearly unsurvivable, regardless of helmet use. Such extreme crashes were 30% of the 63 fatalities in Thailand and 57% of the 54 deaths in Los Angeles, but only about 2-3% of the overall accident population but were. Among the other 97% of riders, universal helmet use could prevent about 80% of fatalities and brain injuries. Helmet use cannot prevent all fatalities because many riders die as the result of below-the-neck injuries that a helmet cannot prevent, but it is extremely effective in preventing death and serious brain injury among riders with survivable below-the-neck injuries.