Both NSW and Victoria found an increased incidence of STIs following PrEP studies, especially rectal chlamydia. Overall, those who participated in the studies but had previous PrEP had no increase in STI rate, those new to PrEP had 20% more STIs than before. The incidence of STIs was 91/100 person years in PrEPX, the Victorian program.
I found it relevant that >50% of participants had no STIs (of 2981 Vic PrEPX participants) with a small group of 13% participants accounting for 53% of all STI diagnoses with ≥3 STIs each. This was driven by numbers of partners and group sex participation rather than condom use.
The good news is that with increased frequency of testing for STIs, despite a small/moderate increase in STIs, duration of STI infection is reduced and this could reduce the ‘burden of disease’ in the community.
Now that we have PrEP PBS listing, these studies support continuing to follow the 3 monthly STI testing guidelines, particularly for the small group with many infections, and remember that there have been no new HIV infections in this group, which is of course the point of PrEP.
Janet is a GP working in Darlinghurst with a special interest in HIV, sexual health womens health and paediatrics.