Use of preexposure prophylaxis and condom purchasing decisions.

Preexposure prophylaxis (PrEP) prevents human immunodeficiency virus (HIV) but not other sexually transmitted infections (STIs). Men who have sex with men (MSM) who take PrEP tend to report reduced condom use, but little is known about the underlying mechanisms. For this study, MSM who take PrEP (i.e., PrEP experienced; n = 88) and MSM who do not (i.e., PrEP naïve; n = 113) completed an online study, including the condom purchase task (CoPT). The CoPT assesses decisions to purchase condoms across escalating prices (range: free-$55) for sex with different types of hypothetical partners: those least likely to have an STD (least STD) and those that participants most want to have sex with (most want sex with). When condoms were free, PrEP-experienced MSM had a lower rate of condom purchasing than did PrEP-naïve MSM. For both partner types, PrEP-experienced MSM reached a price break point (i.e., would not buy condoms) at a lower price than did PrEP-naïve pariticipants. For the most-want-sex-with partner at the price at which participants elected not to buy condoms, only 23% of PrEP-experienced MSM chose to abstain from sex when not purchasing condoms versus 53% among PrEP-naïve MSM. Similar patterns were observed for the least-STD partner. The results support the potential utility of the CoPT in identifying behavioral mechanisms related to condom use and PrEP.