The effects of the integration of an economic strengthening and HIV prevention education programme on the prevalence of sexually transmitted infections and savings behaviours among adolescents: a full-factorial randomised controlled trial in South Africa

BACKGROUND: Multisectoral approaches are thought necessary to prevent HIV among adolescents. We examined whether an economic strengthening (ES) and an HIV-prevention education intervention improved outcomes when combined versus separately. METHODS: We conducted a full-factorial randomised controlled study to randomise participants into all possible intervention groups based on the two interventions: economic strengthening only (ES-only), HIV-prevention only (HIV-only), both interventions combined (ES+HIV) and no intervention (control). We measured sexually transmitted infections (STIs), self-reported economic and sexual behaviours/knowledge, and pregnancy at a pre-intervention and two post-intervention assessments. Eligible participants were adolescents 14 to 17 years old from a programme supporting vulnerable families in Gauteng Province, South Africa. We estimated intervention effects using repeated measures, generalised linear mixed models. RESULTS: A total of 1773 adolescents participated (57% female). ES+HIV adolescents had the lowest STI prevalence at first endline; however, the comparison with the control was not significant (OR 0.62, 95% CI 0.27 to 1.41). ES-only or HIV-only groups were not significantly better than the control on STI prevalence (OR 1.53, 95% CI 0.73 to 3.20 and OR 1.47, 95% CI 0.69 to 3.12, respectively). STI prevalence became more similar among the groups at second endline. ES-only adolescents were more likely to participate in savings groups (p=0.004) and plan to save for education (p=0.001) versus the control. ES+HIV adolescents were more likely to plan to save for education versus the control (p=0.001) and HIV-only groups (p=0.002) but did not differ significantly from the ES-only group (p=0.803). The ES+HIV intervention’s effect on HIV knowledge was significant compared with the control (p=0.03) and ES-only groups (p<0.001), but not when compared with the HIV-only group (p=0.091). Effects on pregnancy, sexual behaviours or other economic behaviours were not significant. CONCLUSIONS: We could not confirm the ES and HIV interventions, separately or combined, were effective to reduce STI prevalence. Evaluations of multicomponent interventions should use full-factorial designs to fully assess effects. TRIAL REGISTRATION NUMBER: NCT02888678