Does gender moderate the relationship between polydrug use and sexual risk-taking among Australian secondary school students under 16years of age?

Introduction and Aims. This study examines the association of alcohol and polydrug use with risky sexual behaviour in adolescents under 16 years of age and if this association differs by gender. Design and Methods. The sample consisted of 5412 secondary school students under 16 years of age from Victoria, Australia. Participants completed an anonymous and confidential survey during class time. The key measures were having had sex before legal age of consent (16 years), unprotected sex before 16 (no condom) and latent-class derived alcohol and polydrug use variables based on alcohol, tobacco, cannabis, inhalants and other illegal drug use in the past month. Results. There were 7.52% and 2.55% of adolescents who reported having sex and having unprotected sex before 16 years of age, respectively. After adjusting for antisocial behaviours, peers' drug use and family and school risk factors, girls were less likely to have unprotected sex (odds ratio=0.31, P=0.003). However, the interaction of being female and polydrug use (odds ratio=4.52, P=0.004) was significant, indicating that girls who engaged in polydrug use were at higher risk of having unprotected sex. For boys, the effect of polydrug use was non-significant (odds ratio=1.44, P=0.310). Discussion and Conclusions. For girls, polydrug use was significantly associated with unprotected sex after adjusting for a range of risk factors, and this relationship was non-significant for boys. Future prevention programs for adolescent risky sexual behaviour and polydrug use might benefit from a tailored approach to gender differences