The Swiss STAR trial – an evaluation of target groups for sexually transmitted infection screening in the sub-sample of men

Abstract

OBJECTIVES: In Switzerland, universal health insurance does not cover any routine testing for sexually transmitted infections (STIs), not even in individuals at high risk, and extra-genital swabbing is not standard of care. We determined the prevalence and incidence of human immunodeficiency virus (HIV), viral hepatitis and non-viral STIs in a multicentre prospective observational cohort of multi-partner men who have sex with men (MSM) and other men.MATERIALS AND METHODS: Between January 2016 and June 2017, we offered free STI testing to all men with multiple sexual partners (three or more in the previous 12 months), with follow-up examinations every 6 months. We used multiplex polymerase chain-reaction testing (for Neisseria gonorrhoeae, Chlamydia trachomatis, Trichomonas vaginalis, Mycoplasma genitalium) on pooled swabs (pharynx, urethra/vagina, anus), and antibody tests for HIV and Treponema pallidum at every visit, and for hepatitis B/C at baseline. RESULTS: We screened 779 multi-partner MSM and 92 other men. Previously undiagnosed HIV was found in 0.5% vs 0.0%, respectively and T. pallidum antibodies in 15.3% vs 1.1%. STIs requiring antibiotic treatment comprised: active syphilis 1.7% vs 0.0%; N. gonorrhoeae 10.3% vs 0.0%; C. trachomatis 8.7% vs 1.1%. One in four MSM versus 1 in 100 other multi-partner men had any of these three STIs at baseline. 10.4% vs 1.3% had a history of hepatitis B, 31.9% vs 47.3% had no immunity (HBs-AB <10 IU/l). Ten MSM had HCV antibodies (1.4%), with 8 out of the 10 being MSM with HIV; HCV seroprevalence was 0.3% among HIV-negative MSM. In MSM, incidence of the three bacterial STIs was 25.5 per year over 333 person years of follow-up, HIV incidence was 0.3%. Non-condom-use (in the last 3 months) for anal/vaginal sex was not associated with STIs. Independent risk factors were sex with men (adjusted odds ratio [aOR] 16.4) and the number of sexual partners (aOR 2.3 for >20). CONCLUSION: Among MSM, but not among other multipartner men, STIs, mostly asymptomatic, are common. Given the high risk of onward transmission, low-cost or free routine screening of multi-partner MSM is a public health priority.

Risk Factors and Incidence of Sexually Transmitted Infections in the Swiss HIV Cohort Study

“…Of note, in the SHCS, syphilis is screened for routinely every 1–2 years irrespective of symptoms, which might contribute to the high syphilis incidence in this study compared with other STIs. In a recent survey among asymptomatic MSM with at least 3 sexual partners attending voluntary counseling and testing (VCT) sites in Switzerland, the incidence for syphilis was 42/1000 PYFU, the incidence for gonorrhoea was 147/1000 PYFU, and the incidence for was chlamydia 90/1000 PYFU [ 13 ]. Of note, in this VCT sites study, only 3.6% of the participants had a diagnosed HIV infection at the time of enrollment.…”

“…Furthermore, there might be an underestimation of the overall cases if patients did not report all STIs diagnosed in external settings, including VCT sites, or missed to report specific symptoms. Of note, among people attending a VCT site, 3.8% were already known to be HIV positive [ 13 ]. However, in this context, it is important to optimize screening strategies according to clinical and behavioral characteristics.…”

“…The ability to obtain reliable incidence estimates of STIs is challenging: the majority of infections are asymptomatic, coinfections are frequent, and testing options are limited due to high costs and laboratory burden in many settings [ 12 , 13 ]. Until recently, most studies investigating STIs epidemiology among PWH were limited to certain HIV transmission risk groups such as men who have sex with men (MSM), and there have been limited data about prevalence and long-term incidence of STIs in large, representative cohort studies.…”

Social and behavioural determinants of syphilis: Modelling based on repeated cross-sectional surveys from 2010 and 2017 among 278,256 men who have sex with men in 31 European countries

“…Some countries, therefore, explicitly recommend biannual syphilis-screening in multi-partners MSM. 30 , 31 …”

Evaluating specimen pooling forNeisseria gonorrhoeae,Chlamydia trachomatis, andMycoplasma genitaliumscreening in asymptomatic men who have sex with men

“…13,14 However, these studies included symptomatic MSM or partners of individuals with confirmed Neisseria gonorrhoeae or Chlamydia trachomatis infections, whereas our study participants were exclusively asymptomatic patients, which may account for our different findings. Specimen pooling has been used to determine prevalence of Mycoplasma genitalium infection in both male and female patients 15,16 ; however, to our knowledge, there are no prior studies evaluating whether performance of the assay itself is affected by pooling of samples from multiple sites. Although routine M. genitalium screening is not recommended by the CDC due to a limited knowledge on the effects of asymptomatic infections, 7 epidemiological studies may help define specific patient populations for future research follow-up.…”