Associations between School-Behavior-Health Difficulties and Subsequent Injuries among Younger Adolescents: A Population-based Study.

School-behavior-health difficulties (SBHDs) may alter physical/mental capabilities and consequently increase injury risk during daily activities. This study assessed the associations of potential SBHDs and their cumulative number (SBHDcn) with various injury types among younger adolescents. The study population included 1,559 middle-school adolescents in France (10-18 years, 98% under 16,778 boys and 781 girls). They completed a questionnaire at school-year end collecting socioeconomic features (nationality, family structure, parents' education/occupation/income), school/out-of-school injuries during the school-year (dependent variables), and SBHDs starting before the school-year (low academic performance, alcohol/tobacco/cannabis/other-illicit-drugs use, physical/verbal violence, sexual abuse, perpetrated violence, poor social support, poor general health status, sleep difficulty, depressive symptoms, and suicide attempt). Data were analyzed using logistic regression models and Kaplan-Meier estimates. Injuries were frequent during school-physical/sports-training (10.9%), other-school-training (4.7%), school-free-time (7.4%), out-of-school-sports-activity (16.5%), and traffic (2.2%). Single injury (one injury all injury types combined) and ≥2 injury types affected 23.3 and 7.9% of subjects, respectively. The proportion of adolescents without SBHDs decreased with age more quickly among those with each injury type than among those without injury. Various SBHDs were associated with most injury types, single injury, and ≥2 injury types (sex-age-adjusted odds/relative-risk ratios reaching 11, p < .001). A dose-effect association was found between SBHDcn 1-2/3-5/≥6 and both single injury and ≥2 injury types (sex-age adjusted relative risk ratios reaching 12.66, p < .001, vs. SBHDcn = 0). Socioeconomic features had a moderate confounding role in these associations. SBHDs strongly predict injuries among adolescents. Our findings may inform healthcare providers about their prominent role in detecting/reducing SBHDs and injuries.