STI rates among pre-exposure HIV prophylaxis (PrEP) using and non-PrEP using men who have sex with men (MSM) accessing a regional online STI testing service.

8th June 2022 by Kate Ebbutt

John White (Prevents), Vanessa Apea (Preventx), Sara Day (Sexual Health London)

Introduction 

High STI rates are reported among users of HIV PrEP. Most studies measuring gonorrhoea and chlamydia infections come from clinic-based testing of PrEP users. MSM that take PrEP are increasingly accessing online STI testing services. We determined the rates among PrEP-using MSM accessing STI testing via a large regional online testing service. 

Method 

A retrospective analysis was undertaken of 90039 online STI screening contacts completed between 1/4/2021 and 31/3/2022 by MSM from 30 local authorities across London. Age, ethnicity data and nucleic acid amplification testing results for gonorrhoea and chlamydia were collated. STI positivity rates were compared between PrEP-using and non-PrEP-using MSM. 

Results 

There were 35546 registrations among PrEP users and 54493 among non-PrEP users. The highest number of screens were completed by 25-34 year olds (49.2%, n=44326), in whom PrEP use was highest (39.7%). 54% (n=48750) of screens were completed by users from racially minoritised groups, the largest being those of other Asian background and Black Caribbean ethnicity amongst PrEP users and non-PrEP users, respectively. 

Overall rates of STI positivity among PrEP users vs. non-PrEP-users, respectively, were:

• gonorrhoea: 10.6% vs. 5.4%
• chlamydia: 8.7% vs. 4.4%
  • (X²=667.6, 555.7; p <0.00001 for both comparisons). 

Discussion 

We observed significantly higher rates of chlamydia and gonorrhoea among PrEP-using MSM accessing online STI testing. Given the high STI burden among PrEP users and the acceptability of large-scale online testing in this population, integration of online testing into PrEP delivery programmes alongside risk reduction support might enable more frequent and accessible testing and treatment of STIs.