1. Selection and Hawthorne effects in HIV prevention trial among young South African women Results from the HPTN 068 cohort Molly Rosenberg, MPH, PhD Harvard Center for Population and Development Studies Cambridge, MA July 20, 2016 Coauthors: Audrey Pettifor, Rhian Twine, James Hughes, Xavier Gomez-Olive, Ryan Wagner, Amanda Selin, Catherine Macphail, Kathleen Kahn

2. Research question: Did HIV trial alter schooling behavior of participants? HPTN 068 study 2010 2013 2014 2009 Agincourt HDSS education data collected 2012 2011 HPTN 068 enrollment begins 2015 HPTN 068 intervention ends Agincourt HDSS education data collected  HPTN 068 Cash transfers & HIV 2011-2015 Null findings: High school attendance and low HIV rates in both arms  Agincourt HDSS Annual census of underlying study population  Analytic cohort All young women in study area, regardless of HPTN 068 status

3. Selection and Hawthorne effects Selection effect: At baseline, study participants already more likely to be enrolled in school Hawthorne effect: Differences remain in cohort restricted to those enrolled in school at baseline

4. Key conclusions  Those who participated in the trial, regardless of study arm, were more likely to remain in school than non-participants Both selection and Hawthorne effects may have diminished differences between study arms One plausible explanation for null study effect  Associations were strongest at older ages During HIV-vulnerable period in the transition to adulthood  Aspects of HPTN 068 study could potentially be adapted for school retention interventions to prevent HIV: Adults showing interest in schooling of young women Cohesive group environment HIV testing and counseling

5. The HIV Prevention Trials Network is sponsored by the National Institute of Allergy and Infectious Diseases, the National Institute of Mental Health, and the National Institute on Drug Abuse, all components of the U.S. National Institutes of Health. ACKNOWLEDGEMENTS HPTN 068 study team and participants - Audrey Pettifor, PI MRC/Wits Rural Public Health and Health Transitions Unit (Agincourt) – Kathleen Kahn and Steve Tollman Harvard Center for Population and Development Studies