Multiple substance use and self-reported suicide attempts by adolescents in 16 European countries.

Substance use and suicide attempts are high-risk behaviors in adolescents, with serious impacts on health and well-being. Although multiple substance use among young people has become a common phenomenon, studies of its association with suicide attempts are scarce. The present study examines the association between multiple substance use and self-reported suicide attempts in a large multinational sample of adolescent students in Europe. Data on multiple substance use (tobacco, alcohol, tranquillizers/sedatives, cannabis, other illegal drugs) and self-reported suicide attempts were drawn from the 2007 European School Survey Project on Alcohol and Other Drugs (ESPAD). The ESPAD survey follows a standardized methodology in all participating countries. The present study is based on 45,086 16-year-old adolescents from 16 countries that had used the optional "psychosocial module" of the questionnaire, thereby including the question on suicide attempts. Logistic regression analyses were performed to examine the associations of any self-reported suicide attempt (dependent variable) with substance use controlling for country and gender. The strongest association with self-reported suicide attempts was for any lifetime tranquillizer or sedative use (odds ratio 3.34, 95 % confidence interval 3.00-3.71) followed by any lifetime use of illegal drugs other than cannabis (2.41, 2.14-2.70), 30-day regular tobacco use (2.02, 1.84-2.21), 30-day frequent alcohol use (1.47, 1.32-1.63) and any 30-day cannabis use (1.37, 1.18-1.58). The odds ratio of reporting a suicide attempt approximately doubled for every additional substance used. These findings on the association between multiple substance use, including legal drugs (tranquillizers or sedatives and tobacco), and the life-threatening behavior of suicide attempts provide important cues for shaping prevention policies.