Assessing risk compensation post-voluntary medical male circumcision in Zambia

1. Assessing risk compensation post-voluntary medical male circumcision in Zambia Paul C. Hewetta, Petra Toddb, Nicolas Grauc, Erica Soler-Hampejsekc, Kumbutso Dzekedzeked, Barbara S. Menschc aPopulation Council, Zambia, bUniversity of Pennsylvania, cUniversidadde Chile, dPopulationCouncil, New York, eDzekedzeke, Inc.

2. Background Government of the Republic of Zambia has set ambitious targets for scaling up voluntary medical male circumcision (VMMC) services. Target: MC 2.0 million HIV negative men aged 15−49, approximately 80% of the eligible population by 2015. • Objectives of this analysis: • Assess risk compensatory behaviors post MC • Focus on men in a population based cohort • Across 2 years of observation • Assessing 6 indictors of risk behavior • Estimation methods account of selectivity of uptake of circumcision

3. Risk compensation: Evidence • Kisumu, Kenya: Mattson et al., 2008 (sub-study) • Propensity score of 18 risk behaviors • Incident infections of gonorrhea, chlamydia, trich • No stat sign. differences: MC, not MC; all declined • HIV testing and counseling: 1m, 3m, 6m, 12m • Rakia, Uganda: Gray et al., 2012 • Post-trial FU for 2-years (control, MC) - 22% no MC • No observable self-selection MC, ~MC • Sex active 12m, # partners, condom use, alcohol • No stat. sign. differences MC & non-MC • HIV testing & health education : Enroll, 6m, 12m, 24m

4. Question What about risk compensation in a program with national scale and less intensive counseling and follow-up? Example: Zambia Over 725,000 circumcisions conducted since 2008.

5. Methods Since 2010, PC has been annually following a representative cohort of men & women in Zambia. Primary objective: To assess the prevalence of risk compensation post-VMMC. • Information collected: • Demographics • VMMC Knowledge, beliefs and attitudes • VMMC status and timing • Sexual behavior and experiences of STIs • Perceptions of HIV risk

6. Methods (cont.) To-date, the study has collected three rounds of data within a 24month timeframe • Round 1 Nov 2010 to Apr 2011 • Round 2 Sep 2011 to Dec 2011 • Round 3 Sep 2012 to Jan 2013 • Round 4 Oct 2013 to Feb 2014

7. Methods (cont.) Indicators assessing risk compensation • Sex with 2+ partner in last year • Unprotected sex • Sex after alcohol use • Experience of STI symptom in last year • Paid for sex in last year • Statistical Analysis • Instrumental variables GMM regression • Logit regression with fixed effects • Difference-in-difference matching Estimation approaches addresses endogeneity of circumcision uptake

8. Results – MC Uptake Since 2008 through early 2013… 21% of sample men were recently circumcised 16% between R1 (2010) & R3 (2013). 21% 12% 5%

9. Results – Risk Compensation Note: models includes covariate controls † p < .10; * P < .05

10. Conclusions Controlling for endogeneity of circumcision uptake… • No evidence of risk compensation in 2-years • MC men may be less risky than uncircumcised Source: Halletet al., 2008 – Southern Africa