1. A prospective study of risk compensation following male circumcision as an HIV prevention method in Nyanza Province, Kenya: interim results Presented by: Robert C. Bailey PhD, MPH - University of Illinois Investigators: Robert C. Bailey, PhD, MPH - University of Illinois Kawango Agot, PhD, MPH - IRDO, Kisumu, Kenya Nelli Westercamp, PhDc, MPH - University of Illinois

2. Circumcised men Change in behavior before and after MC Baseline visit 6-month follow up Ever had sex82% Had sex in the past 6 months *59%65% Used condoms last time had sex * (sexually active only) 49%52% mean (median; IQR) Number of partners in past 6 months (sexually active in the past 6 months) 1.5 (1; 0-2)1.6 (1; 0-2) Acts of intercourse in the last 30 days * (sexually active in the past 6 months) 1.5 (0; 0-2)2.0 (0; 0-2) * p<0.05

3. Circumcised men vs. controls Change in behavior before and after MC G = Group effect p value T = Time effect p value Circumcision Control Proportion of men reporting ever having sex G=0.46 T=0.01 Proportion of men reporting having sex in the past 6 months G=0.62 T=0.001 Proportion of men reporting using condoms at last sex G=0.85 T=0.10 Mean number of partners in the past 6 months G=0.69 T=0.02 Mean frequency of sex in the past 30 days G=0.93 T=0.01

4. Summary and conclusions When comparing circumcised men to themselves before MC it appears they have sex more often, but with the same number of partners and with increased condom use. The control group has similar trends over time, indicating that changes in behavior are unlikely to be related to circumcision Based on these results, we found no evidence of risk compensation 6 months after the circumcision among young Kenyan men In the future, we will report results from 24 months of follow-up on the approximately 3200 men in this prospective study.