Risk compensation: a male phenomenon? Results from a controlled intervention trial promoting helmet use among cyclists

Estimating lives saved and serious injuries reduced by bicycle helmet use in Colorado, 2006-2014

Using the methodology developed by the National Highway Traffic Safety Administration (NHTSA) for motorcyclists, this paper estimates bicycle helmet effectiveness factors (HEFs), defined as the percentage greater chance that a helmeted bicyclist will avoid a fatality or serious injury relative to a non-wearer. We analyse reported motor vehicle-bicycle collisions in Colorado between 2006 and 2014. We conclude that NHTSA's motorcycle HEF methodology did not provide reasonable results given underreporting of low-severity collisions of helmeted bicyclists. The HEF methodology may be applied to bicycles in future research if more complete bicyclist collision reporting can be obtained. To account for underreporting, we calibrated our bicycle HEFs to past research and found that approximately one of every two bicyclists killed may have survived (HEF = 0.50) and one of every three seriously injured bicyclists may have been less seriously injured (HEF = 0.33) if wearing a helmet at the time of the collision.

Are car safety systems associated with more speeding violations? Evidence from police records in Israel

Over the past decade, the popularity of installing advanced driver-assistance systems (ADAS) in cars has increased markedly. However, the effectiveness of ADAS is subject to debate, primarily because these systems intervene in drivers' perceptions and actions and could lead to adaptive behavior. Using complete national data for the installation of three leading safety systems and speeding tickets issued over the course of an entire year, allowed us to pinpoint the impact of these safety systems at a national level. Employing zero-inflated negative binomial regression models, we found that the installation of the three safety systems was associated with higher number of speeding tickets. These findings are in line with the literature that indicates adaptive behavior in the context of risk. However, when we accounted for the proneness to commit other traffic violations, the effect of the safety systems on the prevalence of speeding tickets was evident only for those prone to violations. Further research should be conducted to identify which drivers will be more likely to be affected and under what circumstances and safety system types.

An examination and extension of the Peltzman effect during the Covid-19 pandemic

Since the first COVID-19 case was confirmed in Germany, the German government has introduced various measures to counteract the pandemic. The implementation of safety measures can have counterproductive effects: people engage in risk compensatory behavior (fewer safety behaviors) after regulations are introduced and obligated by the government, which is known as the Peltzman effect (Peltzman, 1975). Based on the Peltzman effect, the researchers of this study hypothesized that people complied less with safety behaviors and took more health risks (e.g. keep less distance) after the implementation of more stringent COVID-19-related regulations (quarantine obligation and face mask duty) between the two measurement periods of this study. They also extended the Peltzman model by hypothesizing moderating roles of age, gender, and perceived COVID-19 threat. Results of the longitudinal survey study (N = 989, T1: 26 March - 31 March 2020 and T2: 27 April - 4 May 2020) confirm that people indeed complied less with safety recommendations over time associated with strengthened COVID-19-related regulations. Perceived COVID-19 threat to those in a person's surroundings (e.g. family, neighbors) had a positive impact on compliance, but age and gender had no effect. This extends the literature on the Peltzman effect by adding perceived COVID-19 threat as a new relevant construct, enabling the development of more effective safety preventions in the future.

Profiling Cycling Trauma throughout the Body with and Without Helmet Usage in a Large United States Health-care Network

BACKGROUND

This study aimed to characterize bodily injury patterns associated with helmet usage by comparing trauma sustained by helmeted and helmetless cyclists admitted to a large US health-care system.

MATERIALS AND METHODS

A prospective trauma registry associated with a large regional United States health-care network was queried for bicycle injuries resulting in hospital admission over a 5-year period. Data pertaining to helmet usage, demographics, injury description (s), Abbreviated Injury Scale score, Injury Severity Score, and hospital length of stay were collected from 140 patients treated for bicycle-related injuries. Mann-Whitney tests were performed.

RESULTS

Fifty-six of the injured cyclists were helmeted (40%) and 84 were not helmeted (60%). A significantly greater proportion of helmeted cyclists exhibited abrasions and a higher incidence of injury across all injury types (P = <0.001 and 0.003). The number and severity of injury to the external body (P = <0.001 and 0.001) and overall injury severity (P = 0.004) for patients with multiple injuries were also significantly greater among helmeted cyclists. Helmeted cyclists did demonstrate significantly shorter hospital stays (P = 0.021).

CONCLUSION

While the helmeted and helmetless riders admitted to the emergency department exhibit few differences in injury patterns, when significant injury differences were detected, they were more prevalent in helmeted riders. These differences were represented by minor-to-moderate injuries relative to morbidity and mortality, suggesting that the trauma profile of the helmeted and helmetless riders is relatively comparable. Yet, helmetless wearers did have significantly longer hospital stays, which may indicate underlying health disparities and/or behavioral differences.

Risk compensation? The relationship between helmet use and cycling speed under naturalistic conditions

INTRODUCTION

An argument against mandatory helmet use is based on the idea of risk compensation, which means that cyclists might ride faster when wearing a helmet (Lardelli-Claret et al., 2003). However, questionnaire and experimental studies were unable to find evidence for this assumption (Fyhri et al., 2012; Fyhri & Philipps, 2013). Simultaneously, other factors with a potential role in helmet use and cycling speed, such as trip length and rider characteristics have been neglected in such considerations. The goal of the analysis presented in this paper was therefore to investigate the relationship between helmet use and cycling speed under naturalistic conditions while taking characteristics of cyclists and bicycles into account.

METHOD

As part of a naturalistic cycling study, we equipped the bicycles of conventional and e-bike riders with data acquisition systems to record speed and trip distance. It included two cameras (one for the face of the participant, another one for the forward scenery). For the analysis presented in this paper, we used the data of 76 participants (28 conventional bicycles, 48 e-bikes).

RESULTS

In total, participants used their helmet for 56% of all trips. Helmets were used more frequently for longer trips. A linear mixed model, in which trip length, helmet use, bicycle type, age, and gender were used as predictors showed that helmet use did not play a significant role for cycling speed. Instead, all other factors that were analyzed, with the exception of gender, had a significant relationship to cycling speed.

DISCUSSION

The assumption of risk compensation as a result of the use of a helmet could not be confirmed. Instead, the findings seem to support the suggestion that cyclists who undertake trips at potentially higher speed levels are aware of their increased risk, and actively try to reduce it through the use of a helmet.

Recommend or mandate? A systematic review and meta-analysis of the effects of mandatory bicycle helmet legislation

If all cyclistswere wearing helmets, significant numbers of head injuries might theoretically be prevented. Mandatory bicycle helmet legislation increases helmet use but is a controversial measure. Results from 21 studies of the effects of mandatory bicycle helmet legislation on injuries among crash involved cyclists were investigated by means of meta-analysis and the effects of several potential biases were investigated. The summary effect of mandatory bicycle helmet legislation for all cyclists on head injuries is a statistically significant reduction by 20% (95% confidence interval [-27; -13]). Larger effects were found for serious head injury (-55%; 95% confidence interval; [-78; -8]). Among children, larger effects were found when legislation applies to all cyclists than when it applies to children only. There is no clear indication of the results being affected by publication bias. Publication bias may exist, but any existing biases seem to more or less outweigh each other. Results from meta-analysis do not indicate that the results are systematically affected by a lack of control for time trend bias, choice of comparison group or study design (before-after vs. case control). Summary effects may be somewhat overestimated because of a lack of control for potential confounding variables in some of the studies. However, such a bias, if it exists, is not likely to be large. Empirical evidence for the hypotheses that mandatory bicycle helmet legislation deters people from cycling and that helmet wearing leads to behavioral adaptation is mixed. In summary, mandatory bicycle helmet legislation can be expected to reduce head injury among crash involved cyclists. Some adverse effects may occur, but will not necessarily be large or long-lasting. People who may be deterred from cycling, are among those with the highest injury risk and the smallest health effects from cycling. If the overall goal is to improve safety for all cyclists and to increase cycling, mandatory bicycle helmet legislation should be supplemented by other measures, especially improved bicycle infrastructure.

Using data mining techniques to predict the severity of bicycle crashes

To investigate the factors predicting severity of bicycle crashes in Italy, we used an observational study of official statistics. We applied two of the most widely used data mining techniques, CHAID decision tree technique and Bayesian network analysis. We used data provided by the Italian National Institute of Statistics on road crashes that occurred on the Italian road network during the period ranging from 2011 to 2013. In the present study, the dataset contains information about road crashes occurred on the Italian road network during the period ranging from 2011 to 2013. We extracted 49,621 road accidents where at least one cyclist was injured or killed from the original database that comprised a total of 575,093 road accidents. CHAID decision tree technique was employed to establish the relationship between severity of bicycle crashes and factors related to crash characteristics (type of collision and opponent vehicle), infrastructure characteristics (type of carriageway, road type, road signage, pavement type, and type of road segment), cyclists (gender and age), and environmental factors (time of the day, day of the week, month, pavement condition, and weather). CHAID analysis revealed that the most important predictors were, in decreasing order of importance, road type (0.30), crash type (0.24), age of cyclist (0.19), road signage (0.08), gender of cyclist (0.07), type of opponent vehicle (0.05), month (0.04), and type of road segment (0.02). These eight most important predictors of the severity of bicycle crashes were included as predictors of the target (i.e., severity of bicycle crashes) in Bayesian network analysis. Bayesian network analysis identified crash type (0.31), road type (0.19), and type of opponent vehicle (0.18) as the most important predictors of severity of bicycle crashes.

Bicycling injury hospitalisation rates in Canadian jurisdictions: analyses examining associations with helmet legislation and mode share

OBJECTIVES

The purpose of this study was to calculate exposure-based bicycling hospitalisation rates in Canadian jurisdictions with different helmet legislation and bicycling mode shares, and to examine whether the rates were related to these differences.

METHODS

Administrative data on hospital stays for bicycling injuries to 10 body region groups and national survey data on bicycling trips were used to calculate hospitalisation rates. Rates were calculated for 44 sex, age and jurisdiction strata for all injury causes and 22 age and jurisdiction strata for traffic-related injury causes. Inferential analyses examined associations between hospitalisation rates and sex, age group, helmet legislation and bicycling mode share.

RESULTS

In Canada, over the study period 2006-2011, there was an average of 3690 hospitalisations per year and an estimated 593 million annual trips by bicycle among people 12 years of age and older, for a cycling hospitalisation rate of 622 per 100 million trips (95% CI 611 to 633). Hospitalisation rates varied substantially across the jurisdiction, age and sex strata, but only two characteristics explained this variability. For all injury causes, sex was associated with hospitalisation rates; females had rates consistently lower than males. For traffic-related injury causes, higher cycling mode share was consistently associated with lower hospitalisation rates. Helmet legislation was not associated with hospitalisation rates for brain, head, scalp, skull, face or neck injuries.

CONCLUSIONS

These results suggest that transportation and health policymakers who aim to reduce bicycling injury rates in the population should focus on factors related to increased cycling mode share and female cycling choices. Bicycling routes designed to be physically separated from traffic or along quiet streets fit both these criteria and are associated with lower relative risks of injury.

Safe-sex belief and sexual risk behaviours among adolescents from three developing countries: a cross-sectional study

OBJECTIVES

This study intends to evaluate whether the belief that condoms are 100% effective in protecting against HIV infection is associated with sexual risk behaviours among youth.

METHODS

A cross-sectional study was performed in representative samples of high-school students in the Philippines, El Salvador and Peru. Participants completed a self-administered questionnaire. Students were asked about the risk of HIV transmission if one has sex using condoms. They were also asked to indicate whether they had ever had sexual relations and whether they used a condom in their first sexual relation. The sample was composed of 8994 students, aged 13-18.

RESULTS

One out of seven adolescents believed condoms are 100% effective (safe-sex believers). Those adolescents were 82% more likely to have had sex than those without such belief, after adjusting for confounders (OR=1.82; 95% CI 1.51 to 2.21). On the contrary, no association was found between risk perception and condom use. Subgroup and sensitivity analyses produced similar results.

CONCLUSIONS

This is, to the best of our knowledge, the first study conducted specifically to evaluate this phenomenon and that has used the same questionnaire and the same data collection protocol in three different developing countries from Asia, Central and South America. These results reasonably suggest that there could be an association between safe sex beliefs and sexual initiation. Longitudinal studies are needed to better understand this possible association as it could influence how to better promote sexual health.

Increased patterns of risky behaviours among helmet wearers in skiing and snowboarding

BACKGROUND

There has been an ongoing debate as to whether wearing helmets in skiing and snowboarding increases the risk tolerance of participants.

OBJECTIVE

To investigate the roles of demographic and personality variables, and helmet usage in predicting risk taking behaviours in a cross-sectional sample of intermediate and proficient skiers and snowboarders.

METHODS

Risk taking in skiing was measured using a validated 10-item self-report measure which was designated as the outcome variable in a three step hierarchical regression. Independent predictors included age, sex, education, sport, ability, helmet usage, and personality traits that have been associated with risk taking: impulsivity and sensation seeking.

RESULTS

In the final regression model, helmet use significantly predicted variance in risk taking (standardized β=.10, p=.024), and the relationship remained after accounting for variance due to demographic variables and general trait measures. The partial relationship between risk taking and sex, ability, impulsivity, and sensation seeking were also significant (p<.05).

CONCLUSION

High sensation seeking, high impulsivity, male sex, and proficiency were associated with increased patterns of risky behaviours in skiers and snowboarders, and after accounting for these factors, helmet use was a significant predictor of risk taking. The relationship between helmet use and risk taking was modest suggesting that the costs of increased risk taking is not likely to outweigh the protective benefits of a helmet.

Evolution of bicycle helmet use and its determinants in France: 2000-2010

This paper aims to analyse helmet use in France, as a voluntary behaviour rather than a legal requirement, promoted by public awareness campaigns. It aims to investigate the determinants of helmet wearing and to explore its evolution from 2000 to 2010. The analysis relies on data from a series of general population surveys called "Health Barometers": 2000 (n=13,163), 2005 (n=25,651) and 2010 (n=8573). Multivariate logistic regressions were used to identify factors associated with helmet use and time trends. Nearly half of the 15-75 year olds surveyed reported that they rode a bicycle, and among these cyclists, 22.0% reported that they wore a helmet on their last ride. Further analysis by gender reveals that twice as many men than women wore helmets. Over the last decade, helmet use among cyclists has clearly increased, from 7.3% in 2000 to 22.0% in 2010, whereas the influence of social and economic factors, such as unemployment and wage disparities, appears to have decreased. Several determinants of bicycle helmet use were highlighted. To improve the effectiveness of further public information campaigns on helmet use, the key target groups should include women, under 25 year olds and people living in urban areas. Promoting the wearing of helmets among families should also be enhanced, given the higher rate of helmet use by parents as well as children.

Bicycle helmet wearing is not associated with close motor vehicle passing: a re-analysis of Walker, 2007

OBJECTIVES

To re-analyse bicycle overtaking data collected by Walker (2007) with a view to assess factors associated with close passing (<1 m), to adjust for other observed factors in a multivariable analysis, and to assess the extent to which the sample size in the original analysis may have contributed to spurious results.

METHOD

A re-analysis of 2,355 motor vehicle passing events recorded by Walker that includes information on cyclist's distance to the kerb, vehicle size and colour, city of observation, time of day, whether the event occurred while in a bikelane and helmet wearing. Each variable was considered for a final, multivariable model using purposeful selection of variables. The analysis was repeated using multiple logistic regression with passing distance dichotomised by the one metre rule. Bootstrap p-values were computed using sample sizes computed from conventional values of power and effect size.

RESULTS

The previously observed significant association between passing distance and helmet wearing was not found when dichotomised by the one metre rule. Other factors were found to be significantly associated with close passing including cyclists' distance to the kerb, vehicle size and city of observation (Salisbury or Bristol, UK). P-values from bootstrap samples indicate the significance of helmet wearing resulted from an overly large sample size.

CONCLUSIONS

After re-analysis of Walker's data, helmet wearing is not associated with close motor vehicle passing. The results, however, highlight other more important factors that may inform effective bicycle safety strategies.

[Injuries in France: trends and risk factors]

BACKGROUND

Whatever the type of injury considered, prevention requires an improvement in health services' awareness of risk factors. The Health Barometer is a general population survey conducted in France since 1992 to contribute to surveillance in this field. The survey's statistical power and the numerous health topics included in the questionnaire provide accurate information for healthcare professionals and decision-makers.

METHODS

The Health Barometer 2010 was a nationwide telephone survey of 9110 persons representative of the 15-85-year-old population. One part of the questionnaire detailed injuries which had occurred during the past year. The numerous variables recorded enabled application of logistic regression models to explore risk factors related to different types of injury by age group. The findings were compared with the Health Barometer 2005 data to search for temporal trends of injury prevalence.

RESULTS

The data analysis showed that 10.3% of the 15-85-year-olds reported an injury during the past year. This rate was higher than recorded in 2005; the increase was mainly due to domestic accidents and injuries occurring during recreational activities. Both type of injury and risk factors exhibited age-related variability. Domestic accidents and injuries occurring during recreational activities predominated in the older population and were associated with physical or mental health problems (chronic disease, diability, sleep disorders). For younger people, injuries were related to cannabis use, drunkedness, and insufficient sleep. Risk factors were also depended on type of injury: occupational accident-related injuries were linked with social disadvantage (manual worker population) whereas sports injuries were more common in the socially advantaged population.

CONCLUSION

This survey confirms established knowledge and highlights, at different stages of life, new risk factors that contribute to injuries in France. These findings should be helpful for the development of adapted injury prevention programs, by providing a better understanding of the characteristic features of this major public health issue.

Gender stereotypes and superior conformity of the self in a sample of cyclists

In the field of driving, people tend to think they are more competent and more cautious than others. This is the superior conformity of the self (SCS). Our main hypothesis was that, among cyclists, women would show a higher SCS on cautiousness, though men would show a higher SCS concerning competence. 1799 cyclists provided a self-assessment of their own cautiousness and of other people's cautiousness. The same procedure was used for competence. Consistent with the hypothesis, the SCS was gender-specific: it was more prominent for women concerning cautiousness and more prominent for men concerning competence. These results could explain why people tend to ignore the safety campaigns. They also indicate the importance of adapting messages concerning safety measures to gender.