The Effects of Participation in an Intensive HIV Prevention Trial on Long-Term Socio-Demographic Outcomes Among Young Women in Rural South Africa.

BACKGROUND: Research trial participation may influence health outcomes regardless of the intervention assigned, but is often not assessed. SETTING: We investigated how participation in an HIV prevention trial (the HIV Prevention Trials Network (HPTN) 068 study) affected health outcomes 4 years after the study in adolescent girls and young women in South Africa beyond effects of the tested intervention. METHODS: We developed an analytical cohort that included the HIV Prevention 068 trial (HPTN 068) trial participants from the Agincourt Health and Demographic Surveillance System and resembled HPTN 068 trial enrollees (aged 13-20 years and in grades 8-11 in 2011) using inverse probability of treatment weights. We estimated risk differences for the association between trial participation and education and early parity (age <20 years) in 2019, after accounting for differences at baseline between the trial participants and nonparticipants. RESULTS: There were 3442 young women enrolled in grades 8-11 in 2011; 1669 were in the HPTN 068 trial. Trial participants were more likely to have completed secondary school by 2019 (adjusted RD (aRD) 5.0%, 95% confidence interval (CI) 2.2%, 7.9%; 82.3% in trial participants vs. 77.2% in nonparticipants). Trial participants had similar risk of parity before age 20 compared with nontrial participants (aRD 2.3%, 95% CI: -0.8%, 5.5%). CONCLUSIONS: Trial participation did not seem to influence early parity, but did increase educational attainment. Our results are compatible with an explanation of Hawthorne effects from trial participation on schooling behaviors that were small, but observable even 4 years after the end of the trial.