A proposal for the mandatory inclusion of helmets with new children's bicycles.

To reduce bicycle-related head injuries in children, we propose new regulations be established that mandate the inclusion of approved helmets with the sale of all new children's bicycles. Currently, purchasing a helmet is a separate economic decision that acts as a barrier to helmet ownership and use. The inclusion of a helmet with the bicycle would markedly increase helmet ownership. The increased demand would reduce the manufacturing cost per helmet, so the cost of the bicycle with the helmet would be lower than the current retail price of the two separately. This proposal could potentially be implemented by federal or state legislation, a Consumer Product Safety Commission regulation, or voluntary adoption of a practice or standard by bicycle manufacturers. Increased helmet ownership is necessary but not sufficient to raise helmet use rates. The increased ownership generated by this proposal, complemented by enhanced educational, promotional, and legal interventions, is probably the most practical and cost-effective public health strategy available to increase helmet usage and prevent bicycle-related head injuries in children.     

Prevention of bicycle-related head injuries

Each year in the United States, bicycling accidents cause approximately 1,300 deaths and 60,000 injuries. The death and injury rates are particularly high among children. The death rate from bicycle injuries in children exceeds the death rate from accidental poisonings, falls, firearm injuries, and many major illnesses. Head trauma is the most frequent cause of death and serious injury among bicyclists. Bicycle helmets have the potential to decrease the frequency and severity of bicycle-related head injury. Unfortunately, however, most bicyclists do not use a helmet. The helmet-use rate is extremely low among children. The failure of bicyclists, particularly children, to use bicycle helmets presents an opportunity for prevention of thousands of the traumatic head injuries that occur annually in the United States. Helmet use could be encouraged by schools, community safety programs, and office-based education by physicians.     

The Effect of an All-Ages Bicycle Helmet Law on Bicycle-Related Trauma

In 2003, Seattle implemented an all-ages bicycle helmet law; King County outside of Seattle had implemented a similar law since 1994. For the period 2000–2010, the effect of the helmet legislation on helmet use, helmet-preventable injuries, and bicycle-related fatalities was examined, comparing Seattle to the rest of King County. Data was retrieved from the Washington State Trauma Registry and the King County Medical Examiner. Results comparing the proportions of bicycle related head injuries before (2000–2002) and after (2004–2010) the law show no significant change in the proportion of bicyclists admitted to the hospital and treated for head injuries in either Seattle (37.9 vs 40.2 % p = 0.75) nor in the rest of King County (30.7 vs 31.4 %, p = 0.84) with the extension of the helmet law to Seattle in 2003. However, bicycle-related major head trauma as a proportion of all bicycle-related head trauma did decrease significantly in Seattle (83.9 vs 64.9 %, p = 0.04), while there was no significant change in King County (64.4 vs 57.6 %, p = 0.41). While the results do not show an overall decrease in head injuries, they do reveal a decrease in the severity of head injuries, as well as bicycle-related fatalities, suggesting that the helmet legislation was effective in reducing severe disability and death, contributing to injury prevention in Seattle and King County. The promotion of helmet use through an all ages helmet law is a vital preventative strategy for reducing major bicycle-related head trauma.     

Injury Control Recommendations for Bicycle Helmets

ABSTRACT: These guidelines were developed by the Centers for Disease Control and Prevention for state and local agencies and organizations planning programs to prevent head injuries among bicyclists through use of bicycle helmets. The guidelines contain information on the magnitude and extent of the problem of bicycle-related head injuries and potential impact of increased helmet use; characteristics of helmets, including biomechanical characteristics, helmet standards, and performance in actual crash conditions; barriers that impede increased helmet use; and approaches to increasing use of bicycle helmets within the community. In addition, bicycle helmet legislation and community educational campaigns are evaluated. (J Sch Health. 1995;65(4):133–139)     

Age gradient in the cost-effectiveness of bicycle helmets

OBJECTIVES: This study analyzed the reduction in risk of head injuries associated with use of bicycle helmets among persons ages 3 to 70 and the cost-effectiveness of helmet use based on this estimated risk reduction. METHODS: To derive our cost-effectiveness estimates, we combined injury incidence data gathered through a detailed and comprehensive injury registration system in Norway, acute medical treatment cost information for the Norwegian health service, and information reported in the scientific literature regarding the health protective effects of helmet use. The analysis included all cases of head injuries reported through the registration system from 1990 through 1996. We performed an age-stratified analysis to determine the incidence of bicycle-related head injuries, the 5-year reduction in absolute risk of injury, the number needed to treat, and the cost-effectiveness of helmet use. To test the robustness of the findings to parameter assumptions, we performed sensitivity analysis. RESULTS: The risk of head injury was highest among children aged 5 to 16. The greatest reduction in absolute risk of head injury, 1.0 to 1.4% over 5 years estimated helmet lifetime, occurred among children who started using a helmet between the ages of 3 and 13. Estimates indicate that it would cost approximately U.S. $2,200 in bicycle helmet expenses to prevent any one upper head injury in children ages 3-13. In contrast, it would cost U.S. $10,000-25,000 to avoid a single injury among adults. CONCLUSIONS: Bicycle safety helmets appear to be several times more cost-effective for children than adults, primarily because of the higher risk of head injury among children. Programs aiming to increase helmet use should consider the differences in injury risk and cost-effectiveness among different age groups and target their efforts accordingly.     

Trends and subgroup differences in transportation-related injury risk and safety behaviors among high school students, 1991-1997.

PURPOSE: To examine national trends in transportation-related injury risk and safety behaviors among U.S. high school students. METHODS: To examine secular trends in riding with a driver who had been drinking, driving after drinking, and using seat belts, bicycle helmets, and motorcycle helmets, we used logistic regression to analyze data from national Youth Risk Behavior Surveys (YRBS) conducted in 1991, 1993, 1995, and 1997. The YRBS is a self-administered, anonymous survey that uses a national probability sample of U.S. students in public and private schools from grades 9-12 (N = 55,734 for all years combined). RESULTS: The percentages of students who rode with a driver who had been drinking (36.6% in 1997), drove after drinking alcohol (16.9% in 1997), always wore seat belts (33.2% in 1997), and always wore a motorcycle helmet when riding a motorcycle (45.0% in 1997) remained stable between 1991 and 1997. From 1991 to 1997, the percentage of bicycle riders who always wore a helmet when bicycling showed a small but statistically significant increase (1.1% in 1991 to 3.8% in 1997), but helmet use remained low. CONCLUSION: Many young people place themselves at unnecessary risk for motor vehicle- and bicycle-related crash injuries and fatalities. Improved motor vehicle- and bicycle-related injury prevention strategies are needed that specifically target adolescents.     

Promotion of bicycle helmet use among schoolchildren: a randomized clinical trial

Although bicycle helmets have been shown to reduce the rates of head injuries and brain injuries from bicycle mishaps, use of helmets is very uncommon. We compared a comprehensive awareness program to increase bicycle helmet use among schoolchildren to the impact of that same awareness program plus a bicycle helmet subsidy. Results showed no impact of the educational program (no children observed riding to school wore helmets before or after the program). The proportion of helmet wearers at the school that obtained the subsidy increased from 0% to 22% (p = 0.036). An educational program in conjunction with a subsidy may have a significant impact on bicycle helmet use.     

Epidemiology of accidents among users of two-wheeled motor vehicles. A surveillance study in two Italian cities

BACKGROUND: This paper describes a study on the epidemiology of accidents among users of two-wheeled motor vehicles in two Italian cities, Rome and Naples. METHODS: A surveillance study was conducted, recruiting the victims of accidents among users of two-wheeled motor vehicles, visiting the emergency departments of two Italian hospitals. The registration form includes personal data of the involved person, circumstances of the accident, means of arrival at the hospital, type of vehicles involved, helmet use, and eventually third parties involved, and data on the specific injury diagnosis. RESULTS: 736 injured drivers of two-wheeled motor vehicles were investigated for the study (65.1% males, 34.9% females). The mean age of the victims was 22.92 years; 42.9% of the injuries were the result of a single accident. In 35.5% of the injuries cars were involved and in 8.6% of the cases there was a passenger included. Only 12% of the injured people were wearing a helmet. Most of the lesions concerns the knee or lower leg (27.5%), followed by the head (17.5%), elbow and forearm (8.8%), wrist and hand (8.6%), shoulder and upper arm (8.4%) and ankle and foot (6.9%). Helmet use has a protective effect (OR = 0.23), whereas accidents in Naples and during dark hours are associated with an increased risk of head injury (respectively OR = 1.93, and OR = 1.46). CONCLUSION: In this study the lower injury risk due to the use of the helmet on the frequency and severity of head trauma was confirmed. Moreover, the results confirm that Emergency Departments can provide essential epidemiological information, and they have already provided clear arguments in favour of extending the compulsory use of helmets to people above 18 years in Italy.     

Bicycle-related injuries among the elderly--a new epidemic?

Bicycling in Sweden has almost doubled between 1980 and 1992/3 among persons aged 25-64 y. The upward trend is continuing. For the elderly (65 or older) the bicycle is a common means of transport, in both Sweden and a number of other countries. Almost one-third of the Swedish population aged 65 or older bike at some time during the year. The objectives of this study are to describe the pattern of, and trend in, bicycle-related injuries among the elderly in Sweden and to discuss possible means of injury prevention. Mortality data come from official death certificates (1967-96). Hospital-discharge data (1985-96) are also employed, divided into three age groups (-14, 15-64 and 65-), by external cause according to the ICD-9, and also into 'all diagnoses' and 'head injuries'. Number of cases and days of hospital care for persons aged 65 or more, on aggregate and by gender, are reported for 1996. The whole of Sweden and its northern and southern parts separately were investigated. 2830 bicyclists were killed over the period 1967-96, of which 47% were 65 or older. The risk of dying due to bicycling was about 3.7 times greater among the elderly than among children aged 14 or under. There were significant changes in injury trends for all age groups between 1985 and 1996 with regard to hospital care. Annual average decreases for children, of 2.2% for all diagnoses and of 3.4% for head injuries, were observed. For the other two age groups there were increases in all injuries of 3.4% (15-64) and of 2.9% (65-), and increases in head injuries of 4.6% (15-64) and 2.7% (65-). For the elderly living in the southern part of Sweden, there was an increase on average of 2.2% per year over the period, compared with 4.2% for those in the northern part. Males showed a higher incidence of injuries and received longer periods of care than females. Do we have an epidemic of bicycle injuries among the elderly? They face a greater risk of being injured or killed than his/her younger counterpart. For all ages the risk is 7.4 times higher for a bicyclist than for a car driver. The risk for the elderly is about 3 times greater than for the average bicyclist, and as much as 6 times higher for the age group 75-84 y. With some few exceptions, there is no doubt that society has neglected the problem. Decision-makers have a tendency to focus on the relatively young. But people are living longer today and the elderly are healthier, which indicates the need for greater interest and more intervention. We have signs of an epidemic, but one that can be ameliorated or prevented. Just waiting for injury to occur leads only to premature death or lifelong disability.     

Bicycle helmet campaigns and head injuries among children. Does poverty matter?

Objectives   To assess the impact of a community-based bicycle helmet programme aimed at children aged 5–12 years (about 140 000) from poor and well-off municipalities.
Methods   A quasi-experimental design, including a control group, was used. Changes in the risk of bicycle-related head injuries leading to hospitalization were measured, using rates ratios.
Results   Reductions in bicycle-related head injuries were registered in both categories of municipalities. Compared with the pre-programme period, the protective effect of the programme during the post-programme period was as significant among children from poor municipalities (RR 0.45; 95% CI 0.26–0.78) as among those from richer municipalities (RR 0.55; 95% CI 0.41–0.75).
Conclusion   Population-based educational programmes may have a favourable impact on injury risks in poor areas despite lower adoption of protective behaviours.     

Development of a Swedish bicycle helmet promotion programme--one decade of experiences

OBJECTIVE: to describe 10 years of experiences of the Swedish National Bicycle Safety Programme which started during 1990 as part of an initiative taken by the World Health Organization (WHO). In relation to WHO's efforts with regard to accident and injury prevention, a global programme to increase helmet-wearing by two-wheel riders was launched. The idea was to introduce a simple 'vaccine' for everyone that was achievable at a low cost. The Swedish initiative was taken up by the Karolinska Institute and the National Institute of Public Health. METHOD: at an operational level, all available methods and data sources were utilized in the programme: surveillance of injuries, provision of information and advice, training and supervision, environment and product improvements, and legislation. RESULTS: considerable progress has been made in reducing bicycle-related injuries in Sweden over the last two decades. Cycling injuries among the elderly must be a matter of particular concern. CONCLUSIONS: our 10 years of experiences from a bicycle helmet promotion programme lead to the conclusion that there is a case for mandatory helmet wearing, as one of the most important strategies on the national level. But regional and community-based efforts will still need to be more comprehensive. Besides this, efforts must be made to intensify the activities of parties already involved in prevention programmes. New target groups must be approached, such as immigrants, vulnerable social groups, and teenagers. Sustainability of the Swedish Bicycle Helmet Initiative Group, including continued participation of group members and organizations, is the key--in the long term--to protecting Swedish bicyclists against head injuries.     

The cost effectiveness of three programs to increase use of bicycle helmets among children.

Each year in the United States, 280 children die from bicycle crashes and 144,000 are treated for head injuries from bicycling. Although bicycle helmets reduce the risk of head injury by 85 percent, few children wear them. To help guide the choice of strategy to promote helmet use among children ages 5 to 16 years, the cost effectiveness of legislative, communitywide, and school-based approaches was assessed. A societal perspective was used, only direct costs were included, and a 4-year period after program startup was examined. National age-specific injury rates and an attributable risk model were used to estimate the expected number of bicycle-related head injuries and deaths in localities with and without a program. The percentage of children who wore helmets increased from 4 to 47 in the legislative program, from 5 to 33 in the community program, and from 2 to 8 in the school program. Two programs had similar cost effectiveness ratios per head injury avoided. The legislative program had a $36,643 cost and the community-based one, $37,732, while the school-based program had a cost of $144,498 per head injury avoided. The community program obtained its 33 percent usage gradually over the 4 years, while the legislative program resulted in an immediate increase in usage, thus, considering program characteristics and overall results, the legislative program appears to be the most cost-effective. The cost of helmets was the most influential factor on the cost-effectiveness ratio. The year 2000 health objectives call for use of helmets by 50 percent of bicyclists.(ABSTRACT TRUNCATED AT 250 WORDS)     

Bicycle helmet use by children: knowledge and behavior of physicians.

A survey of pediatricians and family physicians in Tucson, Arizona revealed that the majority knew that bicycle accidents are an important cause of childhood mortality and were aware that head trauma causes most bicycle-related deaths. Ninety-two per cent knew that children rarely use bicycle helmets and most believed this was due to inadequate parental awareness of the importance of helmets. Despite this, many physicians never include bicycle safety in patient education provided during well-child care.     

EFFECTS OF BICYCLE HELMET LAWS ON CHILDREN'S INJURIES

In recent years, many states and localities in the USA have enacted bicycle helmet laws. We estimate the effects of these laws on injuries requiring emergency department treatment. Using hospital‐level panel data and triple difference models, we find helmet laws are associated with reductions in bicycle‐related head injuries among children. However, laws also are associated with decreases in non‐head cycling injuries, as well as increases in head injuries from other wheeled sports. Thus, the observed reduction in bicycle‐related head injuries may be due to reductions in bicycle riding induced by the laws. Copyright © 2013 John Wiley & Sons, Ltd.     

Bicycle injuries: road trauma is not the only concern

Data on bicycle injury presentations at a public hospital emergency department for 1991–95 inclusive were analysed to determine the nature and extent of bicycle injuries in the community. There were 599 bicycle injury presentations during the study period, representing more than 2.0% of all injury-related presentations to the emergency department. The main outcome measures were severity and type of injury. Distribution by gender, age, helmet use (1991 and 1992 only), location and mechanism was examined. Rider-only injuries (falls or collisions with stationary objects) accounted for 79.3% of all presentations with only 5.2% due to collisions on a public road or footpath with other moving traffic. Of all injuries where a location was determined, 61.6% occurred in off-road locations. There was little difference in the overall proportions of hospital admissions from injuries on-road (12.4%) and off-road (9.0%). Cyclists injured in on-road collisions with traffic had a higher proportion of hospital admissions (40.0%) than those injured on-road by other mechanisms (7.6%). Children under 10 years of age who had been riding without a helmet suffered a much higher proportion of injuries to the head (53.2% of all injuries) than older cyclists riding without a helmet (19.4%). The majority (83.1%) of head injuries in children under 10 years of age occurred off-road and helmet use was lowest in this group (28.6%). Given previous evidence that helmet use can prevent head injuries, strategies to increase helmet use among cyclists, particularly young children, while riding both on and off-road, should be given a high priority. Rider-only injuries are also an important public health issue.     

Changes in motorcycle-related head injury deaths, hospitalizations, and hospital charges following repeal of Pennsylvania's mandatory motorcycle helmet law

To evaluate the 2003 repeal of Pennsylvania's motorcycle helmet law, we assessed changes in helmet use and compared motorcycle-related head injuries with non-head injuries from 2001-2002 to 2004-2005. Helmet use among riders in crashes decreased from 82% to 58%. Head injury deaths increased 66%; nonhead injury deaths increased 25%. Motorcycle-related head injury hospitalizations increased 78% compared with 28% for nonhead injury hospitalizations. Helmet law repeals jeopardize motorcycle riders. Until repeals are reversed, states need voluntary strategies to increase helmet use.     

Bicycle helmet use by adults: the impact of companionship.

Most of the nearly 1,000 fatal bicycle-related injuries annually could be prevented if riders used safety helmets. Helmet use by adult bicyclists has received relatively little attention because educational campaigns to promote helmet use generally focus on children. Helmet use by adult and child bicyclists at 120 suburban and rural sites in three Maryland counties was observed on two Saturdays in 1990-91 during an evaluation of the impact of a mandatory helmet law. Concordance or discordance of helmet use within various groups of bicyclists--adults only, adults with children, and children only--was recorded. Helmet use among 2,068 adult bicyclists was 49 percent, 51 percent, and 74 percent in the three counties. In two counties combined, 52 percent (365 of 706) of solo adult bicyclists wore helmets compared with only 5 percent (5 of 94) of solo child bicyclists (P < .001). Helmet use or nonuse was concordant among 87 percent of 277 adult-adult pairs, 94 percent of 50 child-child pairs, and 91 percent of 32 adult-child pairs of bicyclists observed. Concordance rates of helmet use or nonuse were similarly high among pairs of adult bicyclists of the same or mixed sexes. These data are consistent with the concept that both adults and children tend to adopt the helmet-wearing behaviors of their companions. Public health efforts focused on adults should encourage helmet use by adult bicyclists both to prevent head injuries and to provide a role model for children.     

Evaluation of a Pilot Program in Rural Schools to Increase Bicycle and Motor Vehicle Safety

Concerned with high bicycle-and motor vehicle-related mortality rates among children, Idaho's South Central District Health Department provided a competition to increase use of 1) seat belts, 2) motor vehicle rear seating, and 3) bicycle helmets among children attending elementary schools in the eight rural counties it serves. Nine of the 44 elementary schools in the health district chose to participate in the contest. Eight schools addressed increasing helmet use, four schools also addressed increasing seat belt use and rear seating, and one school addressed safety in general. A $1,000 prize was awarded to each of four schools judged to have the highest levels of student and community involvement, outreach, creativity, and changes in safety behavior (based on perceptions of outside judges). In 1997, baseline observations were collected for 1) seat belt use and rear seating for children in 28 schools, and for 2) bicycle helmet use among children in 25 schools. In 1998, follow up data were collected for 1) seat belt and rear seating in 42 schools, and 2) bicycle helmet use in 35 schools. Data were analyzed using SAS. Adjusting for differences in baseline rates, regression analysis was used to compare 1997 and 1998 rates for seat belt use, rear seating, and bicycle helmet use for those schools having baseline data. Results showed that although there was no significant difference between participating and non-participating schools in rear-seating behaviors, there was an increase in seat belt and bicycle helmet use for participating schools. Since schools self-selected participation, it is unknown whether those schools were fundamentally different from nonparticipating schools.     

Bicycle helmet use in Sweden during the 1990s and in the future

This paper describes how the use of bicycle helmets in Swedenhas changed for different categories of cyclists from 1988 to2002, and it also estimates future trends in voluntary wearingof bicycle helmets up to the year 2010. Observational studiesof the use of bicycle helmets were conducted once a year from1988 to 2002 at 157 sites in 21 cities. The subjects observedwere children cycling to school (average n = 5471/year) andin their free time (average n = 2191/year), and adults cyclingto workplaces and on public bike paths (average n = 29 368/year).The general trend in helmet use from 1988 to 2002 was determinedby linear regression analysis, and the results were also employedto estimate future helmet wearing for the period 2003–2010.Differences in helmet use according to gender and size of citywere analysed by chi-square tests. From 1988 to 2002, all categoriesof cyclists showed an upward trend in helmet use (p < 0.01,p < 0.001). Helmet wearing increased from about 20 to 35%among children (10 years) cycling during free time, from approximately5 to 33% among school children, and from around 2 to 14% inadults. Total average helmet use rose from about 4 to 17%. However,during the last 5 years of the study period (1998–2002),none of the categories of cyclists studied showed an upwardtrend in helmet wearing. It is estimated that 30% of cyclistswill wear helmets voluntarily by the year 2010, if helmet promotionactivities are continued at the same level as previously. Theresults suggest that Sweden will probably not reach its officialgoal of 80% helmet use unless a national bicycle helmet lawis passed.     

Public Bicycle Share Programs and Head Injuries

Objectives. We evaluated the effect of North American public bicycle share programs (PBSPs), which typically do not offer helmets with rentals, on the occurrence of bicycle-related head injuries.Methods. We analyzed trauma center data for bicycle-related injuries from 5 cities with PBSPs and 5 comparison cities. We used logistic regression models to compare the odds that admission for a bicycle-related injury would involve a head injury 24 months before PBSP implementation and 12 months afterward.Results. In PBSP cities, the proportion of head injuries among bicycle-related injuries increased from 42.3% before PBSP implementation to 50.1% after (P < .01). This proportion in comparison cities remained similar before (38.2%) and after (35.9%) implementation (P = .23). Odds ratios for head injury were 1.30 (95% confidence interval = 1.13, 1.67) in PBSP cities and 0.94 (95% confidence interval = 0.79, 1.11) in control cities (adjusted for age and city) when we compared the period after implementation to the period before.Conclusions. Results suggest that steps should be taken to make helmets available with PBSPs. Helmet availability should be incorporated into PBSP planning and funding, not considered an afterthought following implementation.In the past decade, public bicycle share programs (PBSPs) have become increasingly common in North American cities.1 Often implemented by government agencies, either independently or through a public–private partnership, these networks of bicycles are available for shared use to individuals at some nominal cost relative to the duration of the rental. Such programs are commonly referred to as BIXI programs in Canada (Bicycle-Taxi), and programs in the United States include B-cycle, DecoBike, and CaBi (Capitol Bikeshare in Washington, DC).Traumatic brain injuries (TBIs) account for the majority of bicycle-related deaths and one third of bicycle-related injuries.2 In 2012, an estimated 81 909 bicycle-related head injuries were treated in US emergency departments.3 Bicycle helmets have been shown to reduce the risk of head, brain, and severe brain injury by 63% to 88%.2 Observational data suggest that fatal TBI risk increases 3-fold when an injured cyclist was not wearing a helmet.4 Educational and advocacy efforts have led to the implementation of mandatory helmet legislation for bicyclists aged younger than 18 years in many American cities and states and in several Canadian cities or provinces. Although no US statewide laws currently exist for adult bicyclists, in Canada, 4 provinces (British Columbia, New Brunswick, Nova Scotia, and Prince Edward Island) have legislation requiring helmets for bicyclists of all ages.5The popularity of PBSPs in the United States has been met with enthusiasm from the public health community because they provide cardiovascular exercise and an active lifestyle.6,7 Reduced traffic congestion and emissions are added environmental benefits.7,8 It is evident that the presence of PBSPs increases cycling activity among individuals living near available bicycles.9–11 However, PBSPs do not typically provide helmets, and in an evaluation of the barriers and facilitators to the use of a PBSP in Brisbane, Australia (where helmet use is mandatory), 61% of focus group respondents cited helmet inaccessibility or lack of desire to wear one as the main barriers to using the program.12 Accordingly, some PBSPs and cities offer courtesy helmets or free helmet giveaways,12,13 and a pilot project in the District of Columbia offers tourists loaner helmets.14 However, these efforts appear to be limited and are the exception, rather than the rule. Observational studies indicate that the majority of PBSP users do not wear helmets, and thus have significantly higher odds of riding unhelmeted than private bicycle users.9,13,15–17 Recent research in a single North American city suggests that PBSP implementation was not associated with self-reported collisions or near-misses; however, that study was underpowered and was subject to recall bias.18With more PBSPs potentially resulting in more unhelmeted bicyclists, it is possible that cities with these programs may experience an increase in bicycling-associated head injuries compared with cities with no such programs. Our objective was to assess the effect of PBSPs on the occurrence of bicycle-related head injuries.