Protocol for a cluster randomized controlled trial among young people and their peers to reduce substance use and inequitable gender beliefs in Southern Africa

BACKGROUND AND AIMS: Substance use and the internalization of traditional gender norms, or inequitable gender beliefs, are co-occurring risk behaviors for poorer health and well-being in young people in Southern Africa. Addressing the social and structural factors that reinforce substance use and inequitable gender beliefs, including peer influence and socioeconomic adversity, such as lack of education or employment, is necessary to support sustainable change in these behaviors. However, most existing interventions focus only on changing individual behavior. This study will therefore aim to address this limitation by testing the efficacy of an intervention to reduce substance use and promote equitable gender beliefs, delivered to peer groups and embedded within existing vocational training (VT) programs. DESIGN: Two-arm cluster randomized controlled superiority trial with assessments at baseline, 12-week, and 24-week follow-up. SETTING: Selected VT programs in Zambia, Zimbabwe, and South Africa. PARTICIPANTS: Sixty-six peer groups (N ~ 264 participants) will be recruited, comprised of an index case plus 2 to 5 peers aged 16-24 years old, who use substances together weekly, or binge drink at least monthly, and enrolled in eligible VT programs. INTERVENTION AND COMPARATOR: Peer groups will be randomly allocated [1:1] to receive either: (i) the standard VT program plus Peer Education for Gender Inclusion and Substance Use in Southern Africa (PEGISUS), an 8-session interactive intervention delivered by VT program staff to peer groups or (ii) standard of care (SOC), namely the standard VT program and a referral for substance use services. MEASUREMENTS: The primary outcome is the between-group (PEGISUS vs. SOC) mean difference in change in the total substance use involvement score on the ASSIST (Alcohol, Smoking, and Substance Involvement Screening Test) from baseline to the 12-week follow-up. Secondary outcomes compare the between-group mean difference in (1) other substance use scales on the ASSIST and at other timepoints (i.e. 24-week follow-up) (2); change in gender equitable beliefs using the GEMS (Gender Equitable Men's Scale) from baseline to the 12-week and 24-week follow-up; and (3) VT program attendance and completion rates, employment status, and income earned at the 24-week follow-up. COMMENTS: This will be the first known study in Southern Africa to assess the efficacy of an intervention that addresses substance use and gender equity beliefs among young people and their peers delivered in VT programs. PEGISUS will address socioeconomic adversity and offer a potential pathway to sustainable delivery by embedding the intervention within existing VT programs. If unhealthy risk behaviors are reduced, and employment opportunities are improved, this can lead to improved well-being in the life trajectories of these young people. TRIAL REGISTRATION: Clinicaltrials.gov Trials identifier: NCT06489899. Approved on July 8, 2024. url: https://clinicaltrials.gov/study/NCT06489899?term=NCT06489899?rank=1 . Pan African Clinical Trials identifier: PACTR202502629432188. Approved February 14, 2025. url: https://pactr.samrc.ac.za/TrialDisplay.aspx?TrialID=33370 .