According to the concept of sexual risk compensation, the start of HIV pre-exposure prophylaxis (PrEP) treatment – a drug regimen which effectively prevents acquiring HIV – is associated with rises in sexually-transmitted infections (STIs) as people feel protected against HIV while using it. However, available studies that have looked into the empirical foundation for the concept of sexual risk compensation related to PrEP use actually reported mixed results.
This is according to a study – “Questioning risk compensation: pre-exposure prophylaxis (PrEP) and sexually transmitted infections among men who have sex with men, capital region of Denmark, 2019 to 2022” by Sebastian von Schreeb, Susanne Kriegel Pedersen, Hanne Christensen, et al – that appeared in Eurosurveillance.
In this study, 1,494 participants (99% self-reported cisgender men and less than 1% transgender or non-binary) from the Danish capital region were tapped; 1,326 of them started PrEP during the study period and had at least one follow-up STI test, with the majority of the participants being on a daily treatment regimen (only 0.6% on-demand PrEP use).
Von Schreeb, et al compared STI incidence before and after the initiation of PrEP and in their cohort, PrEP use was linked to a more than twofold increase in the incidence of chlamydia, gonorrhea and syphilis: during the observation time and prior to starting PrEP, the incidence rate of any STI (gonorrhoa, chlamydia or syphilis) was 35.3 per 100 person-years, equivalent to 708 STI diagnoses, and the incidence rate rose to 81.2 STIs per 100 person-years (1,849 diagnoses) during reported use of the treatment.
Overall, PrEP was associated with a 35% higher risk of contracting any STI, which is consistent with findings from similar studies. The authors note that in Denmark, increases in STIs associated with PrEP start are associated to both older and younger individuals.
However, the authors highlighted that their data indicate the detected rise in STI incidence happened before PrEP treatment was started, at around 10–20 weeks prior to it. This led to their hypothesis that “if risk compensation was valid, we would expect STI incidence to increase when people feel protected against HIV. This increase could occur either immediately following the initiation of PrEP, or gradually over time, as they become more assured of the treatment’s protective effect. As no such increase was seen, an alternative interpretation to the association between PrEP and STIs is that changes in sexual risk-taking lead people to PrEP.”
Particularly, “the association is not indicative of risk compensation”.
Von Schreeb, et al, concluded that – based on their study results – the “findings suggest that individuals frequently seek PrEP during periods when they are at increased risk of contracting STIs. This makes PrEP programs a critical point of intervention, both for preventing HIV and STIs.”
