Changes in Sexual Behaviour Following PrEP Initiation Among Australian Gay and Bisexual Men in Relationships: Results from a Prospective Observational Study.

Few studies have examined changes in sexual behaviour following HIV pre-exposure prophylaxis (PrEP) initiation among gay, bisexual and other men who have sex with men (GBM) in relationships. In a national, online, prospective study of GBM in Australia, we compared sexual behaviours prior to and after PrEP initiation among HIV-negative and unknown-HIV-status men (recruited 2014-2017) not taking PrEP at baseline and who completed at least one six-monthly follow-up by July 2018. Among men in relationships who did not initiate PrEP (n = 339), we compared their most recent survey to their prior one, while among men in relationships who initiated PrEP (n = 81), we compared follow-ups before and after PrEP initiation. Among the 81 PrEP-initiators who were in a relationship both before and after initiation, the proportion reporting their regular partner was on PrEP increased from 8.3 to 44.4% (p < 0.001) and the proportion reporting receptive CLAIC increased from 27.2 to 44.4% (p = 0.009). Overall, men who initiated PrEP were more likely to be in a relationship with a partner on PrEP, and it appeared they started PrEP around the same time. Receptive CLAIC also became more common.