Multiple risk behavior and injury: an international analysis of young people.

BACKGROUND Multiple risk behavior plays an important role in the social etiology of youth injury, yet the consistency of this observation has not been examined multinationally. OBJECTIVE To examine reports from young people in 12 countries, by country, age group, sex, and injury type, to quantify the strength and consistency of this association. SETTING World Health Organization collaborative cross-national survey of health behavior in school-aged children. PARTICIPANTS A multinational representative sample of 49 461 students aged 11, 13, and 15 years. MAIN EXPOSURE MEASURES Additive score consisting of counts of self-reported health risk behaviors: smoking, drinking, nonuse of seat belts, bullying, excess time with friends, alienation at school and from parents, truancy, and an unusually poor diet. MAIN OUTCOME MEASURE Self-report of a medically treated injury. RESULTS Strong gradients in risk for injury were observed according to the numbers of risk behaviors reported. Overall, youth reporting the largest number (> or =5 health risk behaviors) experienced injury rates that were 2.46 times higher (95% confidence interval, 2.27-2.67) than those reporting no risk behaviors (adjusted odds ratios for 0 to > or =5 reported behaviors: 1.00, 1.22, 1.48, 1.73, 1.98, and 2.46, respectively; P<.001 for trend). Similar gradients in risk for injury were observed among youth in all 12 countries and within all demographic subgroups. Risk gradients were especially pronounced for nonsports, fighting-related, and severe injuries. CONCLUSIONS Gradients in risk for youth injury increased in association with numbers of risk behaviors reported in every country examined. This cross-cultural finding indicates that the issue of multiple risk behavior, as assessed via an additive score, merits attention as an etiological construct. This concept may be useful in future injury control research and prevention efforts conducted among populations of young people.