LAUSR

INTRODUCTION The U.S. experience with motorcycle helmets affords an important insight into the responses of adolescents to age-specific laws. Political contention has led to a number of U.S. state law changes back and forth between universal and age-specific laws. Because both kinds of law require adolescent motorcyclists to wear helmets, relatively few studies have focused on how the law type affects their behavior. METHOD Differential behavior is tested by a systematic review of literature, leading to a meta-analysis, in relation to the experience of various states' motorcycle helmet laws. An electronic search was conducted for before-and-after studies in U.S. states that include data on adolescent helmet usage - both with a universally applicable motorcycle helmet law, and with an age-restricted law (usually, under-21 or under-18) - from observational, injury or fatality records for a certain period (e.g., 12 months) pre and post the state law change. RESULTS The search yielded ten studies, including two that compared a set of age-specific law states with a set of universal law states over the same time period. Heterogeneity analysis of seven single-state studies with raw data revealed an acceptable fit for a random-effects model. Additional noncompliance with age-restricted laws was indicated by an attributable percentage among exposed of over 65% and odds ratio exceeding 4. CONCLUSIONS About two-thirds of adolescent noncompliance with age-restricted motorcycle helmet usage laws disappears with universal applicability. Evidence from numerous international studies of youth reaction to helmet laws suggests that a large part of the greater compliance with universal laws is due to their conveying a more convincing message that helmets afford protection against injury. Practical Applications: The meta-analysis provides fresh, young-rider perspective on the continuing debate over motorcycle-helmet laws. Broader insight into adolescent psychology suggests considering alternatives to age-restricted laws more widely in safety and health policy.