Daily oral TDF was well tolerated, with reasonable adherence. No significant renal concerns were identified.

Objective To evaluate for changes in sexual behaviors associated with daily pill-use among MSM participating in a PrEP trial. Design Randomized, double-blind, placebo-controlled trial. Participants were randomized 1:1:1:1 to receive tenofovir disoproxil fumarate or placebo at enrollment or after a 9-month delay and followed for 24 months. Methods 400 HIV-negative MSM reporting anal sex with a man in the past 12 months and meeting other eligibility criteria enrolled in San Francisco, Atlanta, and Boston. Sexual risk was assessed at baseline and quarterly visits using Audio Computer-Assisted Self-Interview. The association of pill-taking with sexual behavior was evaluated using logistic and negative-binomial regression for repeated measures. Results Overall indices of behavioral risk declined or remained stable during follow-up. Mean numbers of partners and proportion reporting unprotected anal sex (UAS) declined during follow-up (p<0.05), and mean UAS episodes remained stable. During the initial 9 months, changes in risk practices were similar in the group that began pills immediately vs. those in the delayed arm. These indices of risk did not differ significantly after initiation of pill-use in the delayed arm or continuation of study medication in the immediate arm. Use of poppers, amphetamines, and sexual performance-enhancing drugs were independently associated with one or more indices of sexual risk. Conclusions There was no evidence of risk compensation among HIV-uninfected MSM in this clinical trial. Monitoring for risk compensation should continue now that PrEP has been shown to be efficacious in MSM and other populations and will be provided in open-label trials and other contexts.

In December 1999 the Centers for Disease Control and Prevention's (CDC's) Division of HIV/AIDS Prevention initiated a standardized evaluation system for CDC-funded health department HIV prevention programs. This health department evaluation guidance asks health departments to develop comprehensive evaluation plans and to submit aggregated data on such activities as intervention planning, process monitoring, and outcome evaluation. During the first year of this system, of 65 health departments, 62 submitted evaluation plans, 37 submitted intervention plan data, and 20 submitted process monitoring data. Major issues affecting implementation of a national evaluation system include varying levels of evaluation capacity among health departments, differences between the CDC's taxonomy for national data collection and local definitions, and limitations regarding use of 1st-year data. The CDC has learned that implementation of a standardized evaluation system takes considerable time and that stakeholder involvement and technical assistance and capacity building support are essential.