Background: FEM-PrEP was unable to demonstrate the effectiveness of oral emtricitabine/tenofovir disoproxil fumarate (FTC/TDF) as pre-exposure prophylaxis for HIV prevention because of low adherence. We hypothesized that one reason for the poor adherence was low perceived HIV risk.
Methods: At enrollment and at quarterly follow-up visits, we assessed participants' perceived HIV risk for the subsequent 4 weeks. We used logistic regression to assess factors associated with some (small, moderate, or high) perceived HIV risk. We also used logistic regression with robust variance estimation to assess the association between risk perceptions (none versus some) reported at enrollment and at weeks 12, 24, and 36 and good adherence based on drug concentrations of plasma tenofovir and intracellular tenofovir diphosphate in specimens collected 4 weeks later (at weeks 4, 16, 28, and 40) among 150 randomly selected participants assigned FTC/TDF.
Results: Multiple factors were statistically associated with having some perceived risk, including having sex without a condom, having multiple partners, and not knowing if a partner has HIV. We observed a significant association between having some risk perception and good adherence (odds ratio: 2.0; 95% confidence interval: 1.1 to 3.5; P = 0.016).
Conclusions: Data suggest that participants are likely knowledgeable about factors that increase their HIV risk. Perceived risk seemed to have influenced some participants' decisions to adhere to the study pill within the context of a placebo-controlled clinical trial. Future research can explore the role of risk perception in the uptake of and adherence to pre-exposure prophylaxis, now that FTC/TDF has been shown efficacious.