The human cost of allowing unhelmeted motorcycling in the United States, a study just released by the Insurance Institute for Highway Safety (IIHS) and Highway Loss Data Institute (HLDI), says motorcycle crashes involving riders without helmets is estimated to be responsible for 22,058 preventable fatalities from 1976 to 2022.
The study sought to link the absence of all-rider mandatory helmet-use laws in some states to the number of riders fatally injured in motorcycle crashes.
The description of the study method states: “Counts of helmeted and unhelmeted motorcyclist fatalities were used to estimate population-level helmet use under all-rider helmet laws and in the absence of such laws. The number of lives that could have been saved if helmet use in states that allowed unhelmeted riding was equal to helmet use in states with all-rider helmet laws was estimated for each year and summed over the study years.”
The study posits that 22,058 fewer motorcyclists would have suffered fatal injuries nationwide if all states had all-rider mandatory helmet-use laws from 1976 to 2022. It estimates that fatalities in 2022 would have been ten percent lower. The study notes that only 17 states and the District of Columbia had all-rider mandatory helmet-use laws throughout the study period.
The description of the study method raises some questions. Specifically, how were fatalities linked clinically to the presence or absence of helmet use? Crash injuries that can cause fatal outcomes are not limited to head injuries in either case. So, how were fatalities caused by internal or external hemorrhage and shock, chest trauma, spinal injuries, neurogenic shock, and so on excluded from the fatality count to prevent over-estimation of deaths attributed to traumatic brain injury?
If such exclusion was not used—it is not mentioned in the description of the study method—did the researchers simply assume that if any crash-related data indicated no helmet use at the time of the crash, the fatal outcome had to be attributable to traumatic brain injury?
To answer those questions, I contacted IIHS Director of Media Relations Joe Young. He forwarded the questions to The human cost of allowing unhelmeted motorcycling in the United States author Eric Teoh. Teoh’s response:
Helmet use was not clinically linked to the fatality outcome. Rather, we only looked at whether fatally-injured riders were helmeted or not. We know from a study that helmet use is associated with a 37% reduction in risk of dying in a crash, on average. Certainly, many fatal injuries are not to the head, and some fatal head injuries happen even with a helmet. The current study was done at a macro/average/population level, rather than trying to determine if individual fatalities were/weren’t related to helmet use. So, we used that 37% to come up with an estimate of how many fewer fatalities we’d have with X fatalities if helmet use in the population were A instead of B. Helmet use in the population (not just crash-involved) under all-rider laws is ballpark-90% vs ballpark-50% in states without such laws.
That 37 percent data point is probably from page 9 of the National Highway Traffic Safety Administration’s (NHTSA) Motorcycle Safety 5-Year Plan and this study: Motorcycle Helmet Use and Head and Facial Injuries: Crash Outcomes in CODES-Linked Data.
That study doesn’t link the clinical cause of death in fatal motorcycle crashes to the presence or absence of a helmet, either. Instead, it is a statistical estimate. So, the IIHS data is an estimate based on an estimate. As a result, the study may overestimate the number of fatalities attributable to the non-use of a helmet, where the actual cause of death may be other injuries where helmet use/non-use is not a factor.
The problem with this method is that by not including only clinically verified head injuries where helmet use/non-use is a factor in the outcome, the effectiveness of helmets may be understated and is, at a minimum, unknown.
For motorcyclists who want to know about the effect of helmet use on crash outcomes associated with neck injuries, which was done in the clinical setting, there has been recent research published by the University of Wisconsin School of Medicine and Public Health.
That study debunked the oft-heard claim that helmets cause or contribute to neck injuries. It found helmets do not cause or contribute to neck injuries. Further, the number of severe neck injuries was about double the number among helmetless crash victims compared to those wearing helmets.
Another common outcome of traumatic brain injury and spinal cord injury that is not mentioned in the study is permanent disability, up to and including injuries causing severe disability requiring long-term or permanent inpatient institutional care. This is another significant human cost to consider.
Yet another factor that is as important as helmet use is the stunning failure rate—43.9 percent—among helmets labeled as compliant with DOT FMVSS 218 standards when subjected to testing for compliance with that standard’s physical performance standards. We covered that safety issue recently.
While most people would agree that a helmet offers protection from head injury, up to and including fatal injuries, even helmet manufacturers remind helmet buyers that no helmet can prevent injury or death in all crash incidents.
In 1966, President Johnson signed the National Highway Safety Act. It set the stage for appropriating federal funds so states could improve highway infrastructure, maintenance, and safety.
Initially, the National Highway Safety Act linked federal highway funding to mandatory on-road helmet use by motorcycle riders. Later, the authority to mandate helmet use was passed to the states and uncoupled from access to federal highway funds, resulting in the patchwork of states with differing helmet laws we have now.
The IIHS study advocates for national mandatory helmet laws for all riders as a way to cut the fatality rate associated with motorcycle crashes.
IIHS President David Harkey said, “Requiring all riders to wear helmets is a common-sense rule not that different from requiring people in cars to buckle up. We have an obligation to protect everyone on our roadways through smart policy.”
However, without a national mandatory helmet law, helmet use in the United States is trending higher.
While it’s likely that increased helmet use should help reduce motorcycle crash-related fatalities, the data to support that assertion should be more accurately linked to deaths from head and neck injuries that are actually related to helmet use or non-use. That would more accurately demonstrate the effectiveness of helmet use in preventing death and disability. That is the case that must be made for state legislatures to consider enacting helmet-use laws where they are not in use now. That will take a long time, even with the best of data.
At the federal level, action to ensure helmet users are buying helmets independently tested and proven to pass more rigorous performance standards than those in FMVSS 218 could substantially improve safety and crash survival outcomes much more quickly.
