Long-Term Mediation of a Sexual Risk-Reduction Intervention for South African Adolescents

Objective: Black adolescents in South Africa are disproportionately affected by HIV. A cluster-randomized controlled experiment examining the effects of a sexual risk-reduction intervention successfully reduced self-reported intercourse and unprotected intercourse. Based on long-term follow-up assessments, the present research examines theoretical constructs that could potentially mediate the intervention effects and how time and gender, respectively, moderated the mediation.Method: The behavioral outcome was measured by asking whether participants had had any vaginal sex in the past 3 months. Mediation and moderated mediation were tested based on the 3-, 6-, 12-, 42-, and 54-month postintervention outcomes.Results: Three variables through which the sexual risk-reduction intervention had a significant mediated effect on the behavioral outcome were identified: abstinence career opportunities outcome expectancy (alpha x beta product = -0.086, 95% asymmetric confidence interval [ACI] [-0.126, -0.047]), expected parental approval of sexual intercourse (alpha x beta product = -0.061, [-0.102, -0.025]), and self-efficacy to avoid sexual-risk situations (alpha x beta product = -0.022, [-0.049, -0.001]). The moderated mediation analysis showed that gender moderated the intervention's effects on abstinence prevention outcome expectancy (B = -0.186, SEB = 0.079, p = .019), expected parental approval of sexual intercourse (B = 0.143, SEB = 0.058, p = .013), and self-efficacy to avoid sexual-risk situations (B = -0.293, SEB = 0.112, p = .009). The moderated mediation analysis also revealed that time moderated the effects of the intervention on abstinence career opportunities outcome expectancy (B = -0.293, SEB = 0.106, p = .006), self-efficacy to avoid sexual-risk situations (B = 0.335, SEB = 0.060, p < .001), and cultural myths regarding HIV transmission (B = 0.138, SEB = 0.042, p = .001); and the association between four theoretical constructs and the behavioral outcome: abstinence career opportunities outcome expectancy (B = -0.267, SEB = 0.104, p = .001), self-efficacy to refuse sex (B = -0.132, SEB = 0.043, p = .002), self-efficacy to avoid sexual-risk situations (B = -0.093, SEB = 0.055, p = .009), and HIV risk-reduction knowledge (B = -0.286, SEB = 0.134, p = .003).Conclusions: The present study identifies theoretical constructs that mediated the intervention effects on the sexual behavior among South African adolescents for an extended period of time. The findings also reveal gender differences in psychological mechanisms initiated by a sexual risk-reduction intervention and the long-term temporal dynamics of the intervention.