Effectiveness of a universal, school-based, online programme for the prevention of anxiety, depression, and substance misuse among adolescents in Australia: 72-month outcomes from a cluster-randomised controlled trial

The CSC study found that the universal delivery of a school-based, online programme for the prevention of mental health and substance use disorders among adolescents resulted in improvements in mental health and substance use outcomes at 30-month follow-up. We aimed to compare the long-term effects of four interventions-Climate Schools Combined (CSC) mental health and substance use, Climate Schools Substance Use (CSSU) alone, Climate Schools Mental Health (CSMH) alone, and standard health education-on mental health and substance use outcomes among adolescents at 72-month follow-up into early adulthood.