Sex differences in the associations of nonmedical use of prescription drugs with self-injurious thoughts and behaviors among adolescents: A large-scale study in China.

Background To investigate the sex differences in the associations of nonmedical use of opioids and sedatives with non-suicidal self-injury (NSSI), suicidal thoughts, and suicide attempts. Methods This study presents secondary analyses of the 2015 National School-based Chinese Adolescents Health Survey. A total of 152, 527 students (aged 10-20 years) completing standard questionnaires were included in analyses. Appropriate sampling weights were utilized. Results After adjusting for the demographic profile, academic pressure, and depressive symptoms, nonmedical use of opioids (adjusted odds ratio [aOR]=1.82, 95% confidence interval [CI]=1.691.96) and sedatives (aOR=2.03, 95% CI=1.902.18) remain positively associated with NSSI, and adolescents who reported opioids or sedatives misuse were at a higher risk for suicidal thoughts and suicide attempts. A significant sex difference was found in the effects of nonmedical use of sedatives on NSSI, with the effects in girls stronger than that in boys (Ratio of two odds ratio [ROR]=1.18, P=0.011). Girls reporting nonmedical use of opioids and sedatives also had an increased risk of suicidal thoughts than boys (opioids misuse: ROR=1.25, P=0.002; sedatives misuse: ROR=1.21, P=0.006). Limitations Causal inference could not be tested due to the cross-sectional design. Conclusion Although nonmedical use of opioids or sedatives was associated with the increased risks of NSSI, suicidal thoughts, and suicide attempts among both boys and girls, there exist significant sex differences in these associations, and girls exhibited a higher risk of NSSI and suicidal thoughts than boys. Intervention strategies are needed to help vulnerable adolescents (e.g., those involved in NMUPD), with a focus on girls.