- [Show abstract] [Hide abstract] ABSTRACT: Background: Group sex has been suggested as a potential high-risk setting for HIV and other sexually transmitted infections (STIs) among men who have sex with men (MSM). We investigated whether group sex is associated with lower condom use during anal sex and higher proportions of STIs compared with dyadic sex among HIV-negative MSM between 2009 and 2012. Methods: Cross-sectional data from 7 data waves of the Amsterdam Cohort Studies were used. The sample consisted of 465 MSM who either reported both group and dyadic sex (at n = 706 visits) or dyadic sex only (at n = 1339 visits) in the preceding 6 months. Logistic regression with generalized estimating equations was used to investigate the association between sexual setting (group vs. dyadic sex), condomless anal sex, and STI. Results: Group sex was reported at 35% (706/2045) of visits. Condomless sex was more often reported during dyadic than group sex (odds ratio, 3.64 95% confidence interval, 2.57-5.16). Men who had group sex were more likely diagnosed as having gonorrhea compared with men with dyadic sex (odds ratio, 1.71; 95% confidence interval, 1.08-2.97), but this effect was not retained in the multivariate model. Conclusions: Results demonstrate within-person differences in sexual behavior during group and dyadic sex among MSM. Men were more likely to use condoms during group sex than during dyadic sex. Thus, for some, group sex may not necessarily be risky for HIV infection compared with dyadic sex. However, group sex may be a higher-risk setting for acquiring STIs other than HIV, such as gonorrhea. Group sex encounters should be recognized as distinct sexual settings with specific risk characteristics that need to be addressed accordingly.
- [Show abstract] [Hide abstract] ABSTRACT: The Netherlands is a low-incidence country for acute hepatitis B (HBV) infection (1.2/100,000 in 2010), where it is typically acquired in adulthood through injecting drug use or homosexual exposure. Recently, the number of heterosexually acquired acute infections in the Netherlands has increased. Ethnicity may be a risk factor. We describe trends in the incidence of acute HBV among heterosexual adults in ethnic groups in Amsterdam from 1992 to 2009 and discuss future control of HBV in the Netherlands. We studied all cases of acute HBV acquired in heterosexuals aged ≥15 years in the Amsterdam region (1992-2009, n=238) by ethnic group. Incidence rates were estimated as the average number of cases per 100,000 per year. Using Poisson regression, we calculated univariable and multivariable incidence rate ratios (IRR) by ethnic group over calendar year, by age and gender. The incidence in first generation migrants from HBV-endemic countries (FGM) was 4.1/100,000 showing no trend over time. Since 1999, incidence in Dutch-born cases in Amsterdam has increased by 13% annually from 0.2/100,000 in 1999 to 2.1/100,000 in 2009 (annual IRR 1.13, 95% CI:1.0-1.22). From 2004 to 2009, the incidence in native Dutch/Western in Amsterdam was 1.6/100,000 (reference for IRR), in FGM was 4.3/100,000 (IRR of 2.7, 95% CI:1.8-4.2) and in Dutch-born second generation migrants (SGM) was 3.7/100,000 (IRR:2.4, 95% CI:1.2-4.7). Incidence of acute hepatitis B in Amsterdam in FGM and SGM is higher than in the native Dutch population. Low-endemic countries with migrant populations from HBV-endemic areas should consider offering screening and vaccination to both FGM and SGM.
- [Show abstract] [Hide abstract] ABSTRACT: To determine (trends in) HIV incidence among MSM\ who have recently had postexposure prophylaxis (PEP) prescribed in Amsterdam, compared with MSM participating in the Amsterdam Cohort Studies (ACS). We used data from MSM who were prescribed PEP in Amsterdam between 2000 and 2009, who were HIV-negative at the time of PEP prescription and had follow-up HIV testing 3 and/or 6 months after PEP prescription (n = 395). For comparison, cohort data from MSM participating in the ACS in the same period were used (n = 782). Poisson log-linear regression analyses were performed to model trends in HIV incidence and identify differences in HIV incidence between both cohorts at different time points. Between 2000 and 2009, among MSM who were prescribed PEP, an overall HIV incidence of 6.4 [95% confidence interval (CI) 3.4-11.2] per 100 person-years was found, compared with an HIV incidence of 1.6 (95% CI 1.3-2.1) per 100 person-years among MSM participating in the ACS (P < 0.01). In both cohorts, an increasing trend in HIV incidence over time was observed [incidence rate ratio (IRR(per calendar year)) 1.3 (95% CI 0.9-1.7) and 1.1 (95% CI 1.0-1.2) among MSM prescribed PEP and MSM of the ACS, respectively]. The difference in HIV incidence between both cohorts was most evident in more recent years [IRR(PEP versus ACS in 2009) 4.8 (95% CI 2.0-11.5)]. Particularly in more recent years, MSM recently prescribed PEP had a higher HIV incidence compared with MSM participating in the ACS, indicating ongoing sexual risk behaviour.
- [Show abstract] [Hide abstract] ABSTRACT: Background Transmission of HIV and other Sexually Transmitted Infections (STI) is ongoing in Western populations of Men who have Sex with Men (MSM). The main indicator of sexual risk is unprotected anal intercourse (UAI) with casual sex partners. It was suggested that group sex might be a high risk setting for HIV and STI transmission. Aim of the present study is to identify differences in sexual risk behaviour and STI-rates among MSM engaging in group sex compared to one-on-one casual sex. Methods We used cross-sectional data derived through 6-monthly questionnaires and STI screening (infectious syphilis, gonorrhoea or Chlamydia) from the Amsterdam Cohort Studies (ACS) between December 2008 and December 2009. The study population (n=310) consisted of HIV-negative MSM who reported having engaged in both group sex and one-on-one sex (n=119) and MSM reporting one-on-one sex only (n=191). To identify differences in sexual risk behaviour and STI-rates between MSM engaging in group sex and one-on-one sex, we used χ2 tests, Mann−Whitney U tests and logistic regression analyses, corrected for repeated measures. Results MSM engaging in both group sex and one-on-one sex had less anal intercourse (AI) during group sex (79/119; 66.4%) compared to during one-on-one sex (106/119; 89.1%). Moreover, they were less likely to have UAI during group sex compared to one-on-one sex (OR adj 0.44; 95% CI 0.26 to 0.74). Men engaging in one-on-one sex only reported less AI (129/191; 67.5 %), while UAI-levels were similar (OR adj1.47; 95% CI 0.82 to 2.62) compared to one-on-one sex of men who also engage in group sex. Drug use during sex was associated with UAI (OR adj1.78; 95% CI 1.03 to 3.09), independent of whether sex took place in a group sex or one-on-one sex setting. Finally, men engaging in group sex were more likely to be diagnosed with any STI (13.4% vs 5.1%; p=0.013) compared to men engaging in one-on-one sex only. For men engaging in one-on-one sex only, but not for men engaging in group sex, UAI was associated with being diagnosed with any STI (OR 8.44; 95 % CI 2.0 to 35.2). Conclusions The group sex setting might not pose a threat for HIV-infection in MSM, as UAI-rates were lower during group sex compared to one-on-one sex. However, although they did not report more UAI, men engaging in group sex had higher STI-rates than men engaging in one-on-one sex only. This indicates that men engaging in group sex practice other sexual techniques than AI that contribute to acquiring STI.
- [Show abstract] [Hide abstract] ABSTRACT: Background Are MSM who were prescribed PEP, men with high risk behaviour or men who incidentally had a riskful sexual contact? One way to answer this question is to compare the HIV incidence among MSM who were prescribed PEP with the HIV incidence among MSM without such request, using HIV incidence as a surrogate marker for highly riskful sexual behaviour. Methods The HIV-PEP cohort consisted of MSM who were prescribed a 28 day PEP-course after a riskful sexual contact between 2000 and 2009 in Amsterdam, the Netherlands, who were HIV negative at baseline and had a follow-up HIV test at 3 and 6 months. Predictors for seroconversion were analysed using χ2 tests and Mann–Whitney U tests. The comparison cohort consisted of MSM participating in the Amsterdam Cohort Studies (ACS) who were tested every 6 months in the same study period. The latter cohort aims to represent the overall gay community in Amsterdam. HIV incidences, including 95% CIs, were calculated for both cohorts by dividing newly diagnosed HIV-infections by total Person Years (PY) under observation. Results The HIV-PEP cohort comprised of 395 PEP prescriptions (n=321 MSM with one PEP prescription; n=34 MSM with two or more PEP prescriptions) with a total follow up time of 169.45 PY. The median age at PEP prescription was 35 (IQR 30-41) and 62 % was born in the Netherlands. In 61% of the cases PEP was prescribed for receptive unprotected anal intercourse (RUAI) and MSM who seroconverted were more likely to report RUAI compared to those who did not seroconvert (82% and 60% resp.; p=0.15). In the ACS cohort 809 MSM participated with a total follow-up time of 4412 PY. The median age at visit in the ACS was 32 (IQR 28-36) and 86% was born in the Netherlands. The HIV incidence in the time period 2005–2009, as well as the overall HIV incidence in the total study period, was four times higher in the HIV-PEP cohort compared to the ACS (Abstract O1-S10.01 table 1). In the HIV-PEP cohort the overall HIV incidence was 6.49 (95% CI 3.24% to 11.62%) per 100 PY, compared to 1.59 (95 % CI 1.25% to 2.0% per 100 PY in the MSM in the ACS in the same study period (p<0.001). Conclusions The HIV incidence of MSM who were prescribed a PEP course was four times higher than in the overall gay community in Amsterdam. Our results show that PEP users belong to a group of MSM at high risk for HIV infection. Further analyses will be conducted to compare predictors of HIV seroconversion in both cohorts.