Quantifying heterogeneity in sexual behaviour and distribution of STIs before and after pre-exposure prophylaxis among men who have sex with men.

Objectives: Pre-exposure prophylaxis (PrEP) use may influence sexual behaviour and transmission of STIs among men who have sex with men (MSM). We aimed to quantify the distribution of STI diagnoses among MSM in the Netherlands based on their sexual behaviour before and after the introduction of PrEP. Methods: HIV-negative MSM participating in a prospective cohort study (Amsterdam Cohort Studies) completed questionnaires about sexual behaviour and were tested for STI/HIV during biannual visits (2009-2019). We developed a sexual behaviour risk score predictive of STI diagnosis and used it to calculate Gini coefficients for gonorrhoea, chlamydia and syphilis diagnoses in the period before (2009 to mid-2015) and after PrEP (mid-2015 to 2019). Gini coefficients close to zero indicate that STI diagnoses are homogeneously distributed over the population, and close to one indicate that STI diagnoses are concentrated in individuals with a higher risk score. Results: The sexual behaviour risk score (n=630, n visits=10 677) ranged between 0.00 (low risk) and 3.61 (high risk), and the mean risk score increased from 0.70 (SD=0.66) before to 0.93 (SD=0.80) after PrEP. Positivity rates for chlamydia (4%) and syphilis (1%) remained relatively stable, but the positivity rate for gonorrhoea increased from 4% before to 6% after PrEP. Gini coefficients increased from 0.37 (95% CI 0.30 to 0.43) to 0.43 (95% CI 0.36 to 0.49) for chlamydia, and from 0.37 (95% CI 0.19 to 0.52) to 0.50 (95% CI 0.32 to 0.66) for syphilis comparing before to after PrEP. The Gini coefficient for gonorrhoea remained stable at 0.46 (95% CI 0.40 to 0.52) before and after PrEP. Conclusions: MSM engaged in more high-risk sexual behaviour and gonorrhoea diagnoses increased after PrEP was introduced. Chlamydia and syphilis diagnoses have become more concentrated in a high-risk subgroup. Monitoring the impact of increasing PrEP coverage on sexual behaviour and STI incidence is important. Improved STI prevention is needed, especially for high-risk MSM.

van Wees DA ，Diexer S ，Rozhnova G ，Matser A ，den Daas C ，Heijne J ，Kretzschmar M ... -  《-》

Chemsex and diagnoses of syphilis, gonorrhoea and chlamydia among men who have sex with men in the UK: a multivariable prediction model using causal inference methodology.

In the last decade diagnoses of most STIs have risen among men who have sex with men (MSM). Although a significant proportion of this is likely due to increased STI screening, understanding the role of behavioural drivers remains critical. We measure the associations between stimulant use to enhance and prolong sexual experiences (chemsex) and bacterial STI diagnoses in UK MSM, individually considering HIV-diagnosed MSM, pre-exposure prophylaxis (PrEP) users and other MSM. We used the UK 2017-2018 European MSM Internet Survey data (n=9375). We constructed causal inference models using multivariable logistic regression, calculating adjusted OR (aOR) and 95% CI of the associations between participation in recent (≤12 months) exclusively dyadic or multipartner chemsex versus no chemsex and recent self-reported diagnoses of syphilis, gonorrhoea and chlamydia. Among MSM with an HIV diagnosis, 25% of users indicated recent multipartner chemsex, vs 28% of PrEP users and 5% of other MSM. Adjusting for age, ethnicity, UK birth, cis-trans status, sexual identity, education, settlement size and relationship status, participation in recent multipartner chemsex versus no chemsex was associated with greater odds of recent syphilis, gonorrhoea and chlamydia diagnosis. aORs for recent syphilis, gonorrhoea and chlamydia diagnoses were 2.6 (95% CI 1.7 to 4.1), 3.9 (95% CI 2.6 to 5.8) and 2.9 (95% CI 1.9 to 4.3), respectively, in HIV-diagnosed MSM; 1.9 (95% CI 1.1 to 3.3), 2.9 (95% CI 2.0 to 4.2) and 1.9 (95% CI 1.3 to 2.8), respectively, in PrEP users; and 4.0 (95% CI 2.3 to 6.9), 2.7 (95% CI 1.9 to 3.8) and 2.3 (95% CI 1.6 to 3.4), respectively, in other MSM. Conversely, exclusively dyadic chemsex had no significant associations with bacterial STI diagnoses among HIV-diagnosed MSM, only gonorrhoea (aOR 2.4, 95% CI 1.2 to 4.7) among PrEP users and syphilis (aOR 2.8, 95% CI 1.4 to 5.6) among other MSM. Multipartner chemsex may drive the association between chemsex and bacterial STI diagnoses and thus should be the focus of future tailored chemsex interventions. Additionally, PrEP acceptability among MSM and particularly chemsex participants has generated an emergent group suitable for such interventions.

MacGregor L ，Kohli M ，Looker KJ ，Hickson F ，Weatherburn P ，Schmidt AJ ，Turner KM ... -  《-》

HIV pre-exposure prophylaxis and diagnoses of sexually transmitted infections - observational data from German checkpoints, 01/2019-08/2021.

The impact of starting HIV pre-exposure prophylaxis (PrEP) on diagnoses of sexually transmitted infections (STI) remains unclear. We used data from German HIV/STI Checkpoints collected from 01/2019 to 08/2021 to determine the impact of PrEP use on syphilis, gonorrhoea and chlamydia diagnoses. We used self-reported data on demographics, sexual behaviour, testing and PrEP use, as well as lab-confirmed diagnoses from visits to HIV/STI Checkpoints in Germany. PrEP use was categorized as (1) never used; (2) intention to use; (3) former use; (4) current on-demand use; (5) daily use. In multivariate regression analyses (MRA) with gonorrhoea, chlamydia, and syphilis diagnoses as outcomes, we controlled for age, number of sexual partners, number of condomless anal intercourse (CAI) partners in the last six months, and testing recency. For the analysis, we included 9,219 visits for gonorrhoea and chlamydia testing and 11,199 visits for syphilis testing conducted at checkpoints from 01/2019 to 08/2021. MRA identified age (aOR 0.98; 95%CI 0.97-0.99), number of sexual partners in the past six months (aOR 4.90; 95%CI 2.53-9.52 for 11 + partners), and use of chemsex substances (aOR 1.62; 95%CI 1.32-2.00) as risk factors for gonorrhoea, while age (aOR 0.99; 95%CI 0.98-1.00), number of CAI partners (aOR 3.19; 95%CI 2.32-4.41 for 5 + partners), partner sorting (aOR 1.30; 95%CI 1.09-1.54), and use of chemsex substances (aOR 1.29; 95%CI 1.05-1.59) were risk factors for chlamydia infections. For syphilis, the number of CAI partners (aOR 3.19; 95%CI 1.60-6.34 for 5 + partners) was found to be the only significant risk factor. There was a strong association between PrEP use and the number of sexual partners (≤ 5 vs.>5: aOR 3.58; 95%CI 2.15-5.97 for daily PrEP use), the number of CAI partners in the past six months (≤ 1 vs.>1: aOR 3.70; 95%CI 2.15-6.37 for daily PrEP use), and the number of STI tests performed (suggesting higher testing frequency). Both outcomes were also related to partner sorting, chemsex, and selling sex. Checkpoint visits reporting current PrEP use or intention to start PrEP correlated with eligibility criteria for PrEP, i.e. high partner numbers, inconsistent condom use during anal intercourse, and use of chemsex drugs. Use of HIV-specific prevention methods such as HIV serosorting, PrEP sorting, and viral load sorting was reported more frequently. (Daily) PrEP use was an independent risk factor for a chlamydia diagnosis only.

Marcus U ，Schink SB ，Weber C 《BMC PUBLIC HEALTH》

Sexually Transmitted Infection Screening Among Gay, Bisexual, and Other Men Who Have Sex With Men Prescribed Pre-exposure Prophylaxis in Baltimore City, Maryland.

Human immunodeficiency virus pre-exposure prophylaxis (PrEP) clinical guidelines recommend men who have sex with men (MSM) PrEP users be screened biannually for syphilis and gonorrhea/chlamydia at all anatomic sites. We sought to determine the proportion screened and positive by STI and anatomic site at PrEP initiation and PrEP-care visits and patient-level characteristics associated with screening among MSM PrEP users in Baltimore City, Maryland. Medical records among MSM initiating PrEP between 30 September 2015 and 31 March 2018 were abstracted. STI screening (syphilis and gonorrhea/chlamydia at all anatomic sites) and positivity at PrEP visits ≤12 months following initiation were calculated. Poisson regression with cluster robust SEs was used to assess associations with STI screening. Among 290 MSM initiating PrEP, 43.1% (n = 125) were screened per guidelines at PrEP initiation; 79.3% (230), 69.3% (201), 55.9% (162), and 69.3% (201) were screened for syphilis, urogenital, rectal, and oropharyngeal gonorrhea/chlamydia, respectively. Positivity among those screened was syphilis, 7.8% (n = 18/230); gonorrhea, 5.0% urogenital (10/201), 11.1% rectal (18/162), and 7.5% oropharyngeal (15/201); chlamydia, 5.0% urogenital (10/201), 11.7% rectal (19/162), and 1.5% oropharyngeal (3/201). Reported anal and oral sex (vs neither) was independently associated with STI screening (aPR, 2.11; 1.05-4.27) at PrEP initiation. At biannual PrEP-care visits, STI screening was lower and syphilis and rectal gonorrhea/chlamydia positivity was higher. Observed STI screening levels and disease burden suggest the effectiveness of STI screening in PrEP care for STI prevention may be limited. Our results suggest providers may be offering screening based on sexual practices; clarification of STI screening guidelines for PrEP users is needed.

Schumacher C ，Wu L ，Chandran A ，Fields E ，Price A ，Greenbaum A ，Jennings JM ，IMPACT Partner Collaborative ... -  《-》

Incidence of sexually transmitted infections in men who have sex with men and who are at substantial risk of HIV infection - A meta-analysis of data from trials and observational studies of HIV pre-exposure prophylaxis.

Werner RN ，Gaskins M ，Nast A ，Dressler C ... -  《PLoS One》