LAUSR

We analyzed the concept of risk compensation and how it has been applied in HIV prevention, paying particular attention to the strategy of HIV preexposure prophylaxis (PrEP). In risk compensation, reduced perceptions of risk after the introduction of a preventative intervention lead to more frequent risk-taking behavior. Such a change may undermine the intervention's protective benefits. We found that many studies purporting to investigate risk compensation do not assess or report changes in perceptions of risk, instead relying on behavioral measures. Our analysis suggests a complex and sometimes counterintuitive relationship between the introduction of a new prevention intervention, perceptions of HIV risk, and subsequent changes in behavior. As PrEP is introduced, we believe comprehensive assessment of community-level risk compensation-that is, changes in risk perceptions and behavior as a result of increased optimism about avoiding HIV among people not directly protected by PrEP-should not be omitted. We therefore suggest ways to assess prevention optimism and community-level risk compensation.