Preferences for Current and Future PrEP Modalities Among PrEP-Experienced Gay and Bisexual Men in Australia.

Alternatives to daily dosing of HIV pre-exposure prophylaxis (PrEP) are continuing to emerge. From October 2019 to March 2020, we conducted an online survey of PrEP-experienced gay and bisexual men in Australia about interest in and preference for four different PrEP modalities: daily dosing, event-driven dosing, long-acting injectable (LAI)-PrEP and subdermal PrEP implants. Using data from 1477 participants, we measured interest and preference of different modalities using multivariate logistic regression. High proportions of participants were interested in LAI-PrEP (59.7%), daily PrEP (52.0%), PrEP implants (45.3%) and event-driven PrEP (42.8%). LAI-PrEP was the most frequently selected preference (30.5%), followed by PrEP implants (26.3%), daily PrEP (21.4%) and event-driven PrEP (21.2%). Higher interest and preference for non-daily PrEP modalities were associated with being concerned about side effects and perceived difficulties with daily adherence. As novel modalities emerge, attitudes to them should be considered in public health messaging to facilitate informed decision-making.

Increase in Depression and Anxiety Among Australian Gay and Bisexual Men During COVID-19 Restrictions: Findings from a Prospective Online Cohort Study.

We examined depression and anxiety prior to and during COVID-19 restrictions in Australian gay and bisexual men (GBM). In an online cohort, a COVID-19-focused survey was conducted in April 2020. During 2019 and in April 2020, 664 GBM completed the Patient Health Questionnaire (PHQ-9, measuring depression) and Generalized Anxiety Disorder Assessment (GAD-7, measuring anxiety). Increased depression and anxiety were defined as a ≥ 5 point increase on the respective scales. Mean PHQ-9 and GAD-7 scores increased between 2019 and 2020 (PHQ-9: from 5.11 in 2019 to 6.55 in 2020; GAD-7: from 3.80 in 2019 to 4.95 in 2020). The proportion of participants with moderate-severe depression (PHQ-9 ≥ 10) increased from 18.8% (n = 125) to 25.5% (n = 169), while the proportion of participants with moderate-severe anxiety (GAD-7 ≥ 10) increased from 12.7% (n = 84) to 17.3% (n = 115). Almost one-quarter of participants (n = 158, 23.8%) had increased depression; in these men, mean PHQ-9 increased from 2.49 in 2019 to 11.65 in 2020 (p < 0.001). One-in-five (20.6%) participants (n = 137) had increased anxiety; among these men, mean GAD-7 increased from 2.05 in 2019 to 10.22 in 2020 (p < 0.001). Increases were associated with concerns about job security, reduction in social and sexual connections and opportunities, and being personally concerned about COVID-19 itself. COVID-19 appeared to have a sudden and pronounced impact on depression and anxiety in Australian GBM, with a significant minority showing sharp increases. Ongoing monitoring is required to determine longer-term impacts and GBM need access to appropriate and sensitive supports both during and after the COVID-19 pandemic.

Changes in Sexual Behaviour Following PrEP Initiation Among Australian Gay and Bisexual Men in Relationships: Results from a Prospective Observational Study.

Few studies have examined changes in sexual behaviour following HIV pre-exposure prophylaxis (PrEP) initiation among gay, bisexual and other men who have sex with men (GBM) in relationships. In a national, online, prospective study of GBM in Australia, we compared sexual behaviours prior to and after PrEP initiation among HIV-negative and unknown-HIV-status men (recruited 2014-2017) not taking PrEP at baseline and who completed at least one six-monthly follow-up by July 2018. Among men in relationships who did not initiate PrEP (n = 339), we compared their most recent survey to their prior one, while among men in relationships who initiated PrEP (n = 81), we compared follow-ups before and after PrEP initiation. Among the 81 PrEP-initiators who were in a relationship both before and after initiation, the proportion reporting their regular partner was on PrEP increased from 8.3 to 44.4% (p < 0.001) and the proportion reporting receptive CLAIC increased from 27.2 to 44.4% (p = 0.009). Overall, men who initiated PrEP were more likely to be in a relationship with a partner on PrEP, and it appeared they started PrEP around the same time. Receptive CLAIC also became more common.

Assessing the HIV Prevention Needs of Young Gay and Bisexual Men in the PrEP Era: An Analysis of Trends in Australian Behavioural Surveillance, 2014-2018.

Data from repeated, national behavioural HIV surveillance was used to identify similarities and differences between young gay and bisexual men (YGBM) aged 16-24 (n = 1608) and older GBM aged 25-49 (n = 6266), in order to quantify risks and identify gaps in HIV prevention. Trend analyses from 2014 to 2018 are also reported. While there were similar rates of condomless anal intercourse with casual partners in both age groups, YGBM had lower rates of HIV testing and PrEP use but also fewer male partners. Our results suggest most YGBM have lower HIV risk than older GBM but a minority merit enhanced testing and prevention efforts.

Increases in HIV Testing Frequency in Australian Gay and Bisexual Men are Concentrated Among PrEP Users: An Analysis of Australian Behavioural Surveillance Data, 2013-2018.

Increasing HIV testing frequency in gay and bisexual men (GBM) is critical to reducing the time between HIV infection and diagnosis. Using anonymous national behavioural surveillance data (2013-2018) from 43,753 surveys of Australian GBM, we examined HIV testing frequency trends and factors differentiating PrEP-users, non-PrEP-users reporting two or more tests in the previous year, and non-PrEP-users reporting less frequent testing. The proportion tested at least annually increased from 64.4% in 2013 to 70.8% in 2018 (p-trend < 0.001), and from 73.9% to 84.6% among the 51.6% of men classified as higher-risk. Among higher-risk men, having two or more tests in the previous year increased from 48.0% to 69.3% (p-trend < 0.001). Among higher-risk non-PrEP-users, it increased from 47.2% to 54.8% (p-trend < 0.001), however, there was a decrease since 2016 (p-trend < 0.001). Among PrEP-users, it increased from 82.1% in 2013 to 97.3% in 2018 (p-trend < 0.001). Non-PrEP-using higher-risk men having less frequent tests reported lower risk than PrEP-users and non-PrEP-using men reporting two or more tests in the previous year. However, recent risk behaviour was not uncommon: nearly half reported condomless sex; one-fifth reported receptive condomless sex with ejaculation; over half reported group sex; one-quarter used drugs for the purposes of sex; and one-fifth had more than ten sex partners. Efforts are needed to encourage frequent testing and PrEP use among non-PrEP-users who are at higher-risk.

Effect of age on the association between recreational drug use and sexual risk behaviour: a cross-sectional observational analysis.

Recreational drug use (RDU) among gay and bisexual men (GBM) is associated with higher-risk sexual behaviours, however this has not been well defined among older GBM. We investigated the association between RDU and sexual behaviours among older GBM in Sydney, Australia. 617 GBM aged 35-79 years self-reported their RDU in the past 6 months and sexual behaviours. Age-stratified univariable associations between RDU and behaviour were examined. GBM aged 35-44 years were the most likely to report RDU, with rates decreasing with increasing age (Ptrend < 0.001). Associations between RDU and higher-risk sexual behaviours were most consistently found among GBM aged 35-54 years.

The Meaning of 'Regular Partner' in HIV Research Among Gay and Bisexual Men: Implications of an Australian Cross-Sectional Survey.

Estimates of the proportion of HIV infections coming from within regular sexual relationships among gay and bisexual men (GBM) vary widely. Research surveys use various partner type categories, but there is little understanding of how men classify their partners. We conducted an online cross-sectional survey of Australian GBM exploring sexual relationships, including 2057 men reporting on 2566 regular partnerships. Just over half of the partnerships were considered 'relationships', while the remainder were non-romantic 'fuckbuddy'-style arrangements. In multivariable analysis, factors associated with considering the partnership a 'relationship' were: using a 'romantic' descriptor, partnership length, monogamous agreements, any condomless anal sex with each other, love, and commitment. The category of 'regular partner' can mask diverse partnership types, which have different meanings to GBM, associated behaviours, and HIV risks. Certain HIV prevention techniques may be more suited to particular types of partnerships. 'Fuckbuddy' arrangements need to be more explicitly acknowledged in HIV prevention.

Potential public health benefits of HIV testing occurring at home in Australia.

In many countries, including Australia, policies have recently changed to support HIV self-testing. The decision has created much debate about the public health benefits of the strategy versus the risks. Self-testing for HIV was approved in the US on the basis that it would facilitate greater HIV testing uptake, despite having a lower sensitivity than laboratory HIV immunoassays. We calculated the frequency of self-testing that would be required among Australian gay and bisexual men at high-risk for there to be a public health benefit (detection of HIV infections that would have otherwise remained undiagnosed). At a population level, if access to HIV self-testing led to men supplementing their usual sexual health check-ups (involving a laboratory HIV immunoassay) with one or more self-tests at home, or self-tests led to untested gay and bisexual men having an HIV test for the first time, there would be a public health benefit. If men replaced their average of one laboratory HIV immunoassay per year with self-testing at home, then three self-tests would be needed to counteract the lower sensitivity of the self-test (so zero infections would be missed). If four self-tests were undertaken then additional infections would be detected (ie, there would be a public health benefit). Additional public health benefits include a reduction in the period of undiagnosed infection, which is known to be a period of relatively high infectiousness.

Sexual partner's age as a risk factor for HIV seroconversion in a cohort of HIV-negative homosexual men in Sydney.

Increasing partner age may be an important risk factor for HIV infection in homosexual men. About 20 % of 1,427 participants in the Health in Men study in Sydney, Australia, reported that half or more of their partners were much older. Having more partners who were much older was associated with an increased risk of HIV seroconversion (p trend = 0.002), and this remained significant after adjustment for participants' age, number of regular and casual partners, and sexual risk behaviour (p trend = 0.027). Men who reported much older partners were at increased risk of HIV infection, independent of unprotected anal intercourse with sero-nonconcordant partners.

The converging and diverging characteristics of HIV-positive and HIV-negative gay men in the Australian Gay Community Periodic Surveys, 2000-2009.

To assess the changing health promotion needs of human immunodeficiency virus (HIV)-positive gay men in Australia, we analysed the social and behavioural characteristics of HIV-positive men in the Australian Gay Community Periodic Surveys. We looked at change over time in the characteristics of HIV-positive men (from 2000-2001 to 2008-2009) and compared HIV-positive men with their HIV-negative peers within each time period. Multivariate logistic regression analysis was used to assess independent changes over time within each HIV status group. A total of 21,620 responses were included in the analyses; 10,537 in 2000-2001 and 11,083 in 2008-2009. Between the two time periods, HIV-positive and HIV-negative men became more similar in the following areas: paid employment, sexual identity, number of male sex partners, the likelihood of having a regular male partner and having a seroconcordant regular male partner. The two groups diverged in these areas: age, ethnicity, educational level, social engagement with gay men, types of relationship with regular male partners, likelihood of unprotected anal intercourse with casual male partners and likelihood of HIV disclosure to casual male partners. Workforce participation and educational attainment have improved among HIV-positive gay men since 2000, but they still lag behind their HIV-negative peers in these areas. Because HIV-positive men are an ageing cohort, support services will need to increasingly address issues of HIV, sexuality and ageing with HIV-positive men. The increase in unprotected anal intercourse and HIV disclosure with casual partners means that education and support services will increasingly need to address effective HIV disclosure and non-condom-based risk reduction strategies with both HIV-positive and HIV-negative gay men.

The impact of HIV seroadaptive behaviors on sexually transmissible infections in HIV-negative homosexual men in Sydney, Australia.

BACKGROUND: Human immunodeficiency virus (HIV) seroadaptive behaviors, such as serosorting and strategic positioning, are being increasingly practised by homosexual men; however, their impact on sexually transmissible infections is unclear. METHODS: Participants were 1427 initially HIV-negative men enrolled from 2001 to 2004 and followed to June 2007. Participants were tested annually for anal and urethral gonorrhoea and chlamydia, herpes simplex virus, and syphilis. In addition, they reported diagnoses of these conditions, and of genital and anal warts between annual visits, and sexual risk behaviors. RESULTS: Compared with men who reported no unprotected anal intercourse (UAI), serosorting was associated with an increased risk of urethral (incidence: 6.06 vs. 3.56 per 100 person-years (PY), hazard ratio (HR) = 1.97, 95% confidence interval [CI]: 1.43-2.72) and anal (incidence 3.95 vs. 2.80 per 100 PY, HR = 1.62, 95% CI: 1.11-2.36) chlamydia. Compared with men who reported UAI with HIV nonconcordant partners, men who practised serosorting had significantly lower risk of incident syphilis (incidence 0.18 vs. 1.00 per 100 PY, HR = 0.21, 95% CI: 0.05-0.81) and urethral gonorrhoea (incidence 2.15 vs. 5.52 per 100 PY, HR = 0.61, 95% CI: 0.39-0.96). Compared with men who reported no UAI, strategic positioning was associated with an increased risk of urethral gonorrhoea (incidence 4.11 vs. 2.10 per 100 PY, HR = 1.72, 95% CI: 1.05-2.83) and chlamydia (incidence 8.71 vs. 3.56 per 100 PY, HR = 2.22, 95% CI: 1.55-3.18). Compared with men who reported receptive UAI, the incidence of anal gonorrhoea (incidence 1.48 vs. 3.83 per 100 PY, HR = 0.38, 0.20-0.74) and chlamydia (incidence 3.10 vs. 6.30 per 100 PY, HR = 0.44, 95% CI: 0.27-0.69) was significantly lower in those who practised strategic positioning. CONCLUSION: For men who reported seroadaptive behaviors, rates of some bacterial sexually transmissible infections were higher than in men who reported no UAI. However, rates were lower than for men who reported higher HIV risk behaviors.

Prevalence, incidence, and risk factors for human papillomavirus 16 seropositivity in Australian homosexual men.

BACKGROUND: Human papillomavirus 16 (HPV16) has been causally associated with approximately 70% of anal cancers. This cancer is markedly increasing among homosexual men. There is limited knowledge of the epidemiology and natural history of anal HPV infection in homosexual men. METHODS: Behavioral data and sera for antibodies to HPV16 L1 were collected annually for 1427 HIV-negative and 245 HIV-positive Australian homosexual men. Seroprevalence, seroincidence, and risk factors were calculated. RESULTS: Among HIV-negative men, 25.4% were HPV16 seropositive at baseline compared with 44.3% of HIV-positive men. HPV16 seroincidence was 3.1/100 person-years among HIV-negative men and 1.3/100 person-years among HIV-positive men. Seroincidence among HIV-negative men remained >3% per year until 45 years of age, before declining. In multivariate analyses of data from HIV-negative men, seroprevalent HPV16 was associated with sexual risk behaviors and seropositivity for several viral sexually transmissible infections. Seroincident HPV16 was associated with younger age and unprotected anal intercourse with HIV-positive partners. Among men who predominantly practiced insertive anal intercourse, circumcision was associated with a 57% reduction in seroincident HPV16 (hazard ratio = 0.43, 95% confidence interval: 0.21-0.88, P = 0.021). CONCLUSIONS: HPV16 seroincidence remained common in men until their mid 40s suggesting that vaccination may be protective in sexually active young gay men. Both HPV16 seroprevalence and seroincidence correlated well with markers of higher risk sexual activity, particularly receptive anal sexual practices. An association between circumcision and decreased HPV16 seroconversion in HIV-negative men who preferred the insertive position in anal sex was observed.

Incorrect Knowledge of Event-Driven PrEP "2-1-1" Dosing Regimen Among PrEP-Experienced Gay and Bisexual Men in Australia.

BACKGROUND: Event-driven pre-exposure prophylaxis (ED-PrEP), when taken according to the "2-1-1" dosing method, is highly effective at preventing HIV acquisition for gay, bisexual, and other men who have sex with men (GBM). Any missed doses when using ED-PrEP drastically reduce its effectiveness, so it is vital that people using this method know how to take it correctly. This study investigated Australian GBM's awareness of ED-PrEP and their knowledge of how to take it correctly. METHOD: We conducted a survey of 1471 PrEP-experienced GBM in Australia, between October 2019 and March 2020. The survey assessed awareness and knowledge of the 3 components of the "2-1-1" ED-PrEP dosing regimen (number of pills for loading dose, timing of loading dose, and number of days after sex to take PrEP pills) among GBM. Characteristics associated with ED-PrEP awareness and correct knowledge of how to take ED-PrEP were assessed with multivariate logistic regression. RESULTS: Two-thirds (n = 1004, 68.4%) had heard of ED-PrEP, of whom only one-eighth (n = 125, 12.5%) knew the correct details of the "2-1-1" ED-PrEP method; one-third (n = 339, 33.8%) did not know any of the 3 key components. Awareness of ED-PrEP and correct knowledge was associated with greater belief in PrEP efficacy, university education, and intention to take a nondaily PrEP regimen in the next 6 months. CONCLUSIONS: Although ED-PrEP awareness was considerable, most participants did not know how to use ED-PrEP correctly. Further work is needed to increase awareness and knowledge of ED-PrEP among GBM.

Rates of condom and non-condom-based anal intercourse practices among homosexually active men in Australia: deliberate HIV risk reduction?

OBJECTIVE: Three decades into the HIV epidemic and with the advancement of HIV treatments, condom and non-condom-based anal intercourse among gay men in resource-rich countries needs to be re-assessed. METHODS: The proportions of men engaging in a range of anal intercourse practices were estimated from the ongoing cross-sectional Gay Community Periodic Surveys in six states in Australia from 2007 to 2009. Comparisons were made between HIV-negative men, HIV-positive men with an undetectable viral load and those with a detectable viral load. RESULTS: Condoms play a key role in gay men's anal intercourse practices: 33.8% of HIV-negative men, 25.1% of HIV-positive men with an undetectable viral load and 22.5% of those with a detectable viral load reported consistent condom use with all male partners in the 6 months before the survey. Among HIV-negative men, the second largest group were men who had unprotected anal intercourse (UAI) only in the context of HIV-negative seroconcordant regular relationships. Among HIV-positive men, the second largest group was men who had UAI in casual encounters preceded by HIV status disclosure to some, but not all, casual partners. CONCLUSIONS: A minority, yet sizeable proportion, of men consistently engaged in a number of UAI practices in specific contexts, suggesting they have adopted deliberate HIV risk-reduction strategies. While it is important that HIV behavioural prevention continues to reinforce condom use, it needs to address both the challenges and opportunities of the substantial uptake of non-condom-based risk-reduction strategies.

Lymphogranuloma venereum is rare in Australian community-based samples of men who have sex with men.

Lymphogranuloma venereum (LGV) typing was performed on chlamydia-positive samples obtained in Sydney, Australia, between 2005 and 2007, from community-based cohorts of predominantly asymptomatic HIV-infected and -uninfected men who have sex with men. The number of chlamydia tests and follow-up for each cohort were as follows: 2082 (90.2% of eligible visits) over 2005.1 person-years (PY) of follow-up in the HIV-uninfected cohort; and 521 (70.8% of eligible visits) over 320.2 PY of follow-up in the HIV-infected cohort. One case of rectal LGV in a symptomatic HIV-infected participant was identified among 64 Chlamydia trachomatis infections, giving an LGV incidence in the HIV-infected cohort of 0.3 per 100 PY, 95% Confidence Interval 0.008-1.7. Routine LGV typing of chlamydia infections in asymptomatic Australian men who have sex with men does not appear justified.

Chemoprophylaxis is likely to be acceptable and could mitigate syphilis epidemics among populations of gay men.

BACKGROUND: Over the last decade, syphilis epidemics have resurged around the world, particularly among gay men. An innovative public health response could be the use of chemoprophylaxis. We sought out to determine the acceptability of syphilis chemoprophylaxis and its likely population effectiveness if it were adopted. METHODS: We conducted a mixed-methods study. An online survey (n = 2095 participants) and focus groups (n = 23 participants) were conducted to determine whether syphilis chemoprophylaxis is likely to be acceptable to gay men in Australia. We also developed an individual-based mathematical model that simulated a population of gay men, to explore the potential impact of introducing chemoprophylaxis. RESULTS: Of the 2095 gay men surveyed, 52.7% (95% confidence interval, 50.6%-54.8%) indicated that they would be very likely or slightly likely to use chemoprophylaxis to reduce their chance of acquiring syphilis, increasing to 75.8% (95% confidence interval, 74.0%-77.6%) if chemoprophylaxis would help reduce infections in the gay community. In this model, 70% use-effectiveness of chemoprophylaxis used by 50% of gay men is expected to reduce the number of syphilis cases by ∼50% after 12 months and 85% after 10 years. The majority of the prevention efforts can be gained by targeting subpopulations of men with higher sexual activity. CONCLUSIONS: Chemoprophylaxis offers promise as an acceptable and effective intervention for mitigating syphilis epidemics. The outcomes of a planned placebo-controlled syphilis chemoprophylaxis trial are eagerly anticipated.

High Levels of Prevention-Effective Adherence to HIV PrEP: An Analysis of Substudy Data From the EPIC-NSW Trial.

BACKGROUND: Preexposure prophylaxis (PrEP) prevents HIV infection but relies on good adherence at times of risk, termed "prevention-effective adherence." Most studies assess adherence without reference to sexual behaviur, making it challenging to determine if poor adherence coincides with HIV risk. SETTING: We examined data from a behavioral substudy of a large-scale PrEP implementation trial in New South Wales, Australia. METHODS: Trial participants completed optional brief quarterly surveys, reporting the number of pills taken and sexual behavior with male partners for each day of the "last full week" before each survey. Condomless sex (CLS) was defined as "higher risk" for HIV when with HIV-positive men with detectable/unknown viral loads or unknown HIV status men. Adequate PrEP protection was defined as ≥4 pills for participants assigned male sex at birth and ≥6 pills for participants assigned female sex at birth (including transgender men). RESULTS: Of 9596 participants dispensed PrEP, 4401 completed baseline and ≥1 follow-up survey. Participants reported on 12,399 "last full weeks": 7485 weeks (60.4%) involved CLS and 2521 weeks (33.7% of CLS-weeks) involved higher risk CLS. There were 103 weeks in which participants did not have adequate PrEP protection and had higher risk CLS: 4.1% of higher-risk CLS weeks (n = 103/2521), 1.4% of all CLS weeks (n = 103/7485), and 0.8% of all observed weeks (n = 103/12,399). CONCLUSIONS: In a large PrEP trial, prevention-effective adherence to PrEP was very high at 99%. Our findings illustrate the importance of measuring pill-taking and sexual behavior in the same period so that prevention-effective adherence can be better estimated.

Prevalence, incidence and risk factors for hepatitis C in homosexual men: data from two cohorts of HIV-negative and HIV-positive men in Sydney, Australia.

BACKGROUND: An increasing incidence of hepatitis C virus (HCV) infection in HIV-positive homosexual men has recently been described, but it is uncertain to what extent this reflects sexual transmission. We report prevalence, incidence and risk factors for HCV infection in community-based cohorts of HIV-negative and HIV-positive homosexual men in Sydney. METHODS: Both cohorts recruited participants using similar community-based strategies. Men underwent annual face-to-face interviews, and reported history of injecting-drug use (IDU) and sexual and other behaviours that might lead to blood contact. HCV screening was offered to consenting participants from 2001 to 2007. RESULTS: At baseline, HCV prevalence was 1.07% in the HIV-negative and 9.39% in the HIV-positive men. HCV seropositivity was strongly associated with a history of IDU in both cohorts (OR=56.18, 95% CI 12.55 to 251.5 in HIV-negative, and OR=24.46, 95% CI 5.44 to 110.0 in HIV-positive). In the HIV-negative cohort, five men seroconverted to HCV over 4412.1 person-years of follow-up, an incidence of 0.11 per 100 person-years (95% CI 0.03 to 0.26). Only one seroconverter reported IDU. Of the five, four reported sexual contact with HIV-positive men (HR=8.23, 95% CI 0.91 to 74.28), and two had an incident ulcerative sexually transmitted infection. In the HIV-positive cohort, none seroconverted over 238.1 person-years of follow-up (97.5% CI 0 to 1.54, single-sided). CONCLUSION: HCV prevalence was almost 10 times higher in HIV-positive homosexual men. Although incident HCV infection was uncommon in both cohorts, cases of non-IDU-related transmission did occur, possibly linked to sexual contact with HIV-positive men.

Prevalence, incidence and risk factors for pharyngeal gonorrhoea in a community-based HIV-negative cohort of homosexual men in Sydney, Australia.

BACKGROUND: Pharyngeal gonorrhoea is common in homosexual men and may be important in maintaining community prevalence of anogenital infections. METHODS: From 2003, all participants in the Health in Men cohort of HIV-negative homosexual men in Sydney were offered annual pharyngeal gonorrhoea screening by BD ProbeTec nucleic acid amplification (NAAT) assay with supplementary porA testing. Participants self-reported diagnoses of pharyngeal gonorrhoea made elsewhere between interviews. Detailed sexual behavioural data were collected 6-monthly. RESULTS: Among 1427 participants enrolled, 65 study-visit-diagnosed pharyngeal gonorrhoea infections were identified (incidence 1.51 per 100 person-years, 95% CI 1.19 to 1.93) of which seven infections were identified on baseline testing (prevalence 0.57%, 95% CI 0.23 to 1.17%). Almost 85% of study-visit-diagnosed pharyngeal infections occurred without concurrent anogenital gonorrhoea. The combined incidence of study-visit-diagnosed and self-reported pharyngeal gonorrhoea (n=193) was 4.45 per 100 person-years (95% CI 3.86 to 5.12). On multivariate analysis, incident infection was associated with younger age (p-trend=0.001), higher number of male partners (p-trend=0.002) and reported contact with gonorrhoea (p<0.001). Insertive oro-anal sex ('rimming') was the only sexual behaviour independently associated with incident pharyngeal gonorrhoea (p-trend=0.044). CONCLUSIONS: The majority of pharyngeal gonorrhoea occurred without evidence of concurrent anogenital infection, and the high incidence-to-prevalence ratio suggests frequent spontaneous resolution of NAAT-detected infection. The association of pharyngeal gonorrhoea with oro-anal sex indicates that a broader range of sexual practices are likely to be involved in transmission of gonorrhoea to the pharynx than previously acknowledged. Screening the pharynx of sexually active homosexual men could play a role in reducing the prevalence of anogenital Neisseria gonorrhoeae.

Serosorting may increase the risk of HIV acquisition among men who have sex with men.

BACKGROUND: Serosorting, the practice of seeking to engage in unprotected anal intercourse with partners of the same HIV status as oneself, has been increasing among men who have sex with men. However, the effectiveness of serosorting as a strategy to reduce HIV risk is unclear, especially since it depends on the frequency of HIV testing. METHODS: We estimated the relative risk of HIV acquisition associated with serosorting compared with not serosorting by using a mathematical model, informed by detailed behavioral data from a highly studied cohort of gay men. RESULTS: We demonstrate that serosorting is unlikely to be highly beneficial in many populations of men who have sex with men, especially where the prevalence of undiagnosed HIV infections is relatively high. We find that serosorting is only beneficial in reducing the relative risk of HIV transmission if the prevalence of undiagnosed HIV infections is less than approximately 20% and approximately 40%, in populations of high (70%) and low (20%) treatment rates, respectively, even though treatment reduces the absolute risk of HIV transmission. Serosorting can be expected to lead to increased risk of HIV acquisition in many settings. In settings with low HIV testing rates serosorting can more than double the risk of HIV acquisition. CONCLUSIONS: Therefore caution should be taken before endorsing the practice of serosorting. It is very important to continue promotion of frequent HIV testing and condom use, particularly among people at high risk.