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Adequate adherence to pre-exposure prophylaxis (PrEP) is critical to prevent HIV infection, but accurately measuring adherence remains challenging. We compared two biological [blood drug concentrations in plasma and peripheral blood mononuclear cells (PBMC)] and two self-reported measures (facilitated recall to clinicians and self-report in online surveys) and identified predictors of daily PrEP adherence among gay and bisexual men (GBM) in their first 12 months on PRELUDE, an open-label, single-arm PrEP demonstration project in New South Wales, Australia. 327 participants were enrolled; 263 GBM attended their 12-month follow-up visit (81% retention). Overall, 91% of blood samples had plasma drug concentrations indicative of taking 7 pills/week, and 99% had protective drug concentrations (≥ 4 pills/week). Facilitated recall to clinicians identified 99% of participants with protective adherence as measured by PBMC drug concentrations. Daily adherence measured by facilitated recall was associated with behavioural practices including group sex (aOR 1.33, 95% CI 1.15-1.53, p < 0.001). Retained participants maintained high adherence to daily PrEP over 12 months, confirmed by four different measures. Facilitated recall to clinicians is a suitable measure for assessing PrEP adherence in populations engaged in care where there is established trust and rapport with patients. Trial registration: ClinicalTrials.gov NCT02206555.

We estimated the size of the population of gay-identified men who have sex with men (gay men) eligible for PrEP in Australia under the current national PrEP guidelines. Using input indicators from the Australian Bureau of Statistics, the national representative survey Second Australian Study of Health and Relationships, and national HIV- behavioural surveillance, we calculated the size of the population of sexually active gay men and estimated a range for the number eligible for PrEP using different scenarios based on the guidelines. In 2015, an estimated 108,850 sexually-active 16-69-year-old gay men were classified as at risk of acquiring HIV in Australia. Of these men, 10,558 to 30,913 (9.7%-28.4%) were classified as being at high risk and therefore eligible for PrEP, most commonly due to recent receptive condomless intercourse with casual partners (6.1% to 15.5%), STI infections (5.4% to 10.6%) or the use of crystal methamphetamine (1.4% to 9.4%). The higher estimates included men who may have been at HIV risk for shorter time periods or with fewer partners. Australian PrEP guidelines recommend targeting PrEP to people at high HIV risk. Our estimation of potential PrEP users informed PrEP implementation in Australia. The choice of PrEP eligibility criteria, and interpretation of the guidelines, strongly affects the population estimates. In the future, higher numbers of gay men may become eligible for PrEP, because the estimates are largely defined by and follow trends in condomless anal intercourse. Our estimation methods can be adapted to other settings., Competing Interests: IBZ has received supply of the study medication from Gilead Sciences. AEG has received research funding from BioCSL Ltd, Viiv and Gilead Sciences, as well as conference travel funding and honoraria for educational presentations from Merck. There are no patents, products in development or marketed products associated with this research to declare. This does not alter our adherence to PLOS ONE policies on sharing data and materials.

Background: The New South Wales (NSW) HIV Strategy 2016-2020 aims for the virtual elimination of HIV transmission in NSW, Australia, by 2020. Despite high and increasing levels of HIV testing and treatment since 2012, the annual number of HIV diagnoses in NSW has remained generally unchanged. Pre-exposure prophylaxis (PrEP) is highly effective in preventing HIV infection among gay and bisexual men (GBM) when taken appropriately. However, there have been no population-level studies that evaluate the impact of rapid PrEP scale-up in high-risk GBM. Expanded PrEP Implementation in Communities in NSW (EPIC-NSW) is a population-level evaluation of the rapid, targeted roll-out of PrEP to high-risk individuals., Methods: EPIC-NSW, is an open-label, single-arm, multi-centre prospective observational study of PrEP implementation and impact. Over 20 public and private clinics across urban and regional areas in NSW have participated in the rapid roll-out of PrEP, supported by strong community mobilization and PrEP promotion. The study began on 1 March 2016, aiming to enroll at least 3700 HIV negative people at high risk of HIV. This estimate took into consideration criteria for PrEP prescription in people at high risk for acquiring HIV as defined in the NSW PrEP guidelines. Study participants receive once daily co-formulated tenofovir disoproxil fumarate and emtricitabine (TDF/FTC) and are followed for up to 24 months. Follow-up includes: testing for HIV at 1 month, HIV and other sexually transmissible infections three-monthly, HCV annually and monitoring of renal function six-monthly. Optional online behavioural surveys are conducted quarterly. The co-primary endpoints are (i) HIV diagnoses and incidence in the cohort and (ii) HIV diagnoses in NSW., Discussion: EPIC-NSW is a population-based PrEP implementation trial which targets the entire estimated population of GBM at high risk for HIV infection in NSW. It will provide a unique opportunity to evaluate the population impact of PrEP on a concentrated HIV epidemic., Trial Registration: https://clinicaltrials.gov/ (identifying number NCT02870790 ; registration date 14 August 2016), pre-results stage.

Background Regular sexual partnerships among gay and bisexual men (GBM) who practice condomless anal intercourse (CLAI) have not been well characterised in terms of partnership type, HIV seroconcordance and risk of HIV transmission. Primarily sexual regular partnerships, although commonly reported by gay men, have largely been ignored in research and HIV prevention. Among regular partners reporting CLAI with each other, we determined factors differentiating romantic or committed relationships from partnerships organised primarily around sex ('fuckbuddies') and estimated the proportion of CLAI presenting risk for HIV transmission., Methods: An online, cross-sectional survey of Australian GBM was conducted. Univariate and multivariate generalised estimating equations were used to determine statistical associations., Results: Men reported on 2250 regular sexual partnerships. Over half the partnerships were romantic or committed relationships. Over half the partnerships were HIV-negative seroconcordant (54.9%), 3.1% were HIV-positive seroconcordant, 5.2% were serodiscordant and 36.8% were of unknown seroconcordance. Potential risks presented by CLAI were sometimes mitigated by protective factors, such as having a clear spoken agreement about sex with outside partners, having fewer outside partners, openly discussing HIV risk and having an agreement to reduce risk from outside partners. These protective factors were more often found in romantic or committed relationships than among primarily sexual partnerships, and were less often found in partnerships of unknown seroconcordance., Conclusion: CLAI is more common among regular sexual partnerships considered to be of a romantic, committed nature. However, factors associated with such romantic or committed partnerships can also protect against HIV transmission risk. Unknown seroconcordance, particularly lack of communication about HIV status among primarily sexual partnerships, is a key risk factor that needs to be addressed by HIV education.

Background: In Australia, pre-exposure prophylaxis (PrEP) is targeted to individuals at high risk for HIV infection. We describe the HIV risk profile and characteristics of PRELUDE participants, and evaluate the population validity of the sample in representing high-risk gay and bisexual men (GBM) eligible for PrEP., Methods: PRELUDE is an on-going, open-label, single-arm observational study. Participants were identified in clinics and screened for eligibility using a paper-based risk assessment tool which followed the New South Wales (NSW) PrEP guidelines. Selection was validated using an independent online behavioural survey, completed by study participants upon enrolment. Demographic information was analysed using descriptive statistics, and kappa tests were used to determine agreement between reporting of high-risk practices in the risk assessment and behavioural survey., Results: During 2014-15, 471 individuals were targeted for enrolment; 341 were assessed for PrEP eligibility and 313 were enrolled. Of these, 303 (97%) identified as GBM. Overall, 85% of GBM met at least one high-risk criterion; 68% reported receptive intercourse with an HIV-positive or unknown status casual male partner, and 37% reported methamphetamine use in the three months preceding enrolment. The remaining 15% were enrolled based on medium-risk behaviours, or at the clinicians' discretion. We found an 82% total agreement between self-reported high-risk behaviour and clinicians' categorisation of GBM as being at high risk for HIV based on PrEP eligibility criteria., Conclusions: Behavioural eligibility criteria used by clinicians successfully identified individuals at high risk for HIV infection. This targeted approach ensures that the greatest public health and HIV prevention benefits can be derived in a setting without universal access to PrEP.

Rapid developments in the field of HIV pre-exposure prophylaxis (PrEP) with antiretrovirals offer a promise to bring HIV transmission among gay and other men who have sex with men (MSM) to zero by 2030. This review evaluates studies, which modelled the impact of PrEP on HIV diagnoses, and discusses the progress towards PrEP implementation. Studies in English, conducted after 2010 among MSM in countries of the Organization for Economic Cooperation and Development (OECD) were reviewed. Six modelling studies were included, three of which had been conducted outside the US. None of the published models showed that PrEP alone can reduce HIV diagnoses to zero and eliminate HIV transmission by 2030. However, PrEP in combination with other biomedical interventions can reduce HIV diagnoses on the population level by ~95%. Other upcoming biomedical prevention strategies may strengthen combination prevention. Access to PrEP remains limited, even in the OECD countries. Modelling studies can assist governments with decision-making about PrEP implementation and add urgency to the implementation of PrEP. More work is needed on modelling of the impact of PrEP on HIV diagnoses trends outside the US where PrEP implementation is in its early stages.

We aimed to compare rates of illicit drug-related hospitalisations in HIV-negative (HIV-ve) (n = 1325) and HIV-positive (HIV+ve) (n = 557) gay and bisexual men (GBM) with rates seen in the general male population and to examine the association between self-reported illicit drug use and drug-related hospitalisation. Participants were asked how often they used a range of illicit drugs in the previous 6 months at annual interviews. Drug-related hospital admissions were defined as hospital admissions for mental or behavioural disorders due to illicit drug use (ICD 10: F11-16, F18, F19), drug poisoning (T40-T45, T50) or toxic effect of gases (T53, T59, T65). Drug-related hospitalisations were 4.8 times higher in the HIV-ve cohort [SIR 4.75 (95 % CI 3.30-6.91)] and 3.5 times higher in the HIV+ve cohort [SIR 3.51 (1.92-5.88)] compared with the general population. Periods of weekly drug use [IRR 1.86 (1.01-3.46)], poly-drug use [IRR 2.17 (1.07-4.38)] and cannabis use [low use-IRR 1.95 (1.01-3.77), high use-IRR 2.58 (1.29-5.16)] were associated with drug-related hospitalisation in both cohorts, as was being a consistently high meth/amphetamine user throughout follow-up [IRR 3.24 (1.07-9.83)] and being an inconsistent or consistent injecting drug user throughout follow-up [IRR 3.94 (1.61-9.66), IRR 4.43(1.04-18.76), respectively]. Other risk factors for drug-related hospitalisation indicated the likelihood of comorbid drug and mental health issues in GBM hospitalised for drug use.

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.

HIV 'treatment as prevention' (TasP) is highly effective in reducing HIV transmission in serodiscordant couples. There has been little examination of gay and bisexual men's attitudes towards TasP, particularly regarding men's willingness to act on beliefs about TasP. We conducted an online cross-sectional survey of Australian men in late 2012 to investigate knowledge and beliefs about new developments in HIV prevention. Amongst 839 men (mean age 39.5 years), men tended to disagree that TasP was sufficiently effective to justify reduced condom use, although HIV-positive men had more favourable attitudes. Only a minority of men were aware of any evidence for TasP; and one-quarter incorrectly believed that evidence for the effectiveness of TasP already existed for the homosexual population. One-fifth (20.5%) of men reported that they would be willing to have condomless anal intercourse with an opposite-status sexual partner when the HIV-positive partner was taking HIV treatments. Factors independently associated with such willingness were: HIV-positive serostatus, reporting any serodiscordant or serononconcordant condomless anal intercourse with a regular male partner in the previous six months, reporting any condomless anal intercourse with a casual male partner in the previous six months, and having greater beliefs in the effectiveness of TasP. This indicated that the men most willing to rely on TasP to prevent transmission were already engaging in higher risk practices. Biomedical HIV prevention represents a rapidly changing environment with new research as well as community and policy responses emerging at a fast pace. For men with serodiscordant sexual partners to successfully apply TasP to reducing transmission risk, more support and education is needed to enable better utilisation of TasP in specific relational and sexual contexts.

Background: Behavioural surveillance and research among gay and other men who have sex with men (GMSM) commonly relies on non-random recruitment approaches. Methodological challenges limit their ability to accurately represent the population of adult GMSM. We compared the social and behavioural profiles of GMSM recruited via venue-based, online, and respondent-driven sampling (RDS) and discussed their utility for behavioural surveillance., Methods: Data from four studies were selected to reflect each recruitment method. We compared demographic characteristics and the prevalence of key indicators including sexual and HIV testing practices obtained from samples recruited through different methods, and population estimates from respondent-driven sampling partition analysis., Results: Overall, the socio-demographic profile of GMSM was similar across samples, with some differences observed in age and sexual identification. Men recruited through time-location sampling appeared more connected to the gay community, reported a greater number of sexual partners, but engaged in less unprotected anal intercourse with regular (UAIR) or casual partners (UAIC). The RDS sample overestimated the proportion of HIV-positive men and appeared to recruit men with an overall higher number of sexual partners. A single-website survey recruited a sample with characteristics which differed considerably from the population estimates with regards to age, ethnically diversity and behaviour. Data acquired through time-location sampling underestimated the rates of UAIR and UAIC, while RDS and online sampling both generated samples that underestimated UAIR. Simulated composite samples combining recruits from time-location and multi-website online sampling may produce characteristics more consistent with the population estimates, particularly with regards to sexual practices., Conclusion: Respondent-driven sampling produced the sample that was most consistent to population estimates, but this methodology is complex and logistically demanding. Time-location and online recruitment are more cost-effective and easier to implement; using these approaches in combination may offer the potential to recruit a more representative sample of GMSM.

We aimed to describe HIV risk practices of gay men who travel locally, regionally and overseas. We analysed data from the Sydney Gay Community Periodic Survey 2009 about high-risk sexual practices in four locations (locally, while travelling in NSW, Australia and overseas) and with partners of HIV positive, negative and unknown serostatus in each location. Analyses of associations used generalized log-binomial estimation procedures with Type I error of 5 %. Of 1,839 sexually active participants, 70.1 % reported having sex locally. 19.7 % elsewhere in NSW, 20.1 % interstate and 18 % overseas. Unprotected anal intercourse (UAI) was reported by 29.9, 28.6, 21.3 and 19.3 % of men in each location respectively. There was no difference in the levels of UAI locally and elsewhere in NSW, but UAI levels were lower in other Australian locations [adjusted prevalence rate ratio (APRR) = 0.76; 95 % confidence interval (95 % CI) 0.66-0.88] and overseas (APRR = 0.76; 95 % CI 0.65-0.89). UAI was more likely if partners were seroconcordant HIV positive (APRR = 1.67; 95 % CI 1.32-2.11) and less likely if partners were of different HIV serostatus (APRR = 0.39; 95 % CI 0.33-0.47) as compared to seroconcordant HIV negative partners. UAI was associated with group sex and use of party drugs. In this community sample, UAI levels were higher in the local context than in travel destinations, suggesting that familiarity between partners may play a role. High-risk sexual practices can nevertheless contribute to bridging different HIV epidemics and HIV transmission across borders. HIV prevention programs should develop effective approaches to target sexually adventurous gay men and HIV transmission associated with travel.

Since there is little evidence about gay community norms across the world, we reviewed published literature in this area and discuss implications for prevention and research. Eight databases were searched for articles and 16 were considered suitable for analysis. All used quantitative methodology and seven were based on a published theoretical framework. The most common theory employed by four out of the seven papers was the Theory of Reasoned Action. All papers reviewed examined norms on condom use but norms on other risk reduction practices were not explored in these papers. Seven (44 %) studies found those men who perceived strong social support from their peers, were less likely to engage in unprotected anal intercourse. This finding suggests that social support from partners and community members plays a role in shaping safe sex norms. Better understanding of norms may help to redress HIV behaviour change programmes, particularly at the time when HIV diagnoses rates are increasing in most gay communities across the world.

Background: We aimed to describe the current use of antiretrovirals(ARVs) before unprotected anal intercourse (UAI) among Australian gay men, which may represent informal HIV preexposure prophylaxis (PrEP)., Methods: Using data from Australian Gay Community Periodic Surveys conducted in 2011, we assessed the preventive use of ARVs before UAI and its association with sociodemographic characteristics, sexual practices, and drug use in the preceding 6 months. Associations were assessed using multivariate logistic regression analysis., Results: Of 3677 sexually active non-HIV-positive men, 2.5%reported taking ARVs before UAI. The likelihood of ARV use before UAI was significantly higher if any of the following behaviors were also reported: .1 sex partner; UAI with casual partners, irrespective of reporting UAI with regular partners [adjusted odds ratio (AOR) = 2.36; 95% confidence interval (CI): 1.24 to 4.48] or not (AOR = 2.71; 95% CI: 1.44 to 5.07); injecting drugs at least monthly (AOR = 2.56; 95% CI: 1.03 to 6.36); using “party” drugs,occasionally (AOR = 2.23; 95% CI: 1.33 to 3.73) or regularly(AOR = 5.34; 95% CI: 2.99 to 9.56); and group sex while using party drugs, occasionally (AOR = 2.42; 95% CI: 1.29 to 4.53) or regularly (AOR = 5.31; 95% CI: 2.62 to 10.76). Among non-HIV positive men in regular relationships with HIV-positive partners or partners of unknown HIV status, 1.7% and 4.7%, respectively, reported preventive ARV use before UAI., Conclusions: Our findings illustrate sporadic use of ARVs before UAI among gay men in Australia, which was associated with high-risk casual sex and party drug use. These initial data contribute to a much needed understanding of the informal use of ARVs for HIV prevention.

Successful antiretroviral treatments, achievements in gay acceptance and human rights, and internet use have prompted changes in gay socialising which create potential challenges for engaging with gay men for HIV surveillance and research. We used data from the Australian behavioural surveillance and explored (i) the relationship between community engagement and HIV related practices, and (ii) time trends in gay men's engagement with the gay community. Analyses were conducted using log-binomial regression and chi-square test for trend. The proportion of men who socialized mainly with gay men declined and the Internet use to connect with sex partners increased over time. Gay social engagement was associated with HIV positive serostatus, unprotected anal intercourse with regular partners and a high frequency of HIV/STI testing. Our findings indicate a shift in how gay men socialise and find partners. We discuss the challenges for ongoing engagement with gay men for behavioural surveillance and HIV research.

Background: Gay men who request nonoccupational postexposure prophylaxis (PEP) may seek preexposure prophylaxis (PrEP) should this become available. We explored trends and predictors of PEP use among Australian gay men to inform future biomedical prevention programs., Methods: We used 2001-2010 data from Gay Community Periodic Surveys in 3 Eastern Australian states and assessed PEP awareness and use in the 6 months before each survey, and among HIV-uninfected men in all surveys predictors of PEP use. Analytical methods included chi-square test for trend and multivariate log-binomial estimation of associations., Results: The awareness of PEP significantly increased from 23% in 2001 to 64% in 2010. PEP use also increased from 2.3% to 3.9%, respectively. PEP use was significantly associated with being in a regular relationship with an HIV-serodiscordant partner, higher number of sex partners, engaging in anal intercourse with casual partners, and regularly testing for HIV/sexually transmitted infections. However, fewer than 8% of men who engaged in these practices reported PEP use., Conclusions: Our findings highlight the profiles of current PEP users: men in HIV-serodiscordant relationships, and men having high numbers of casual partners and unprotected anal intercourse with them. These men are in need of effective HIV prevention strategies and may be receptive to preexposure prophylaxis in the future. Presently, targeted HIV education to improve risk assessment skills may prevent some seroconversions through the appropriate use of PEP.

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&emsp14;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.

Background: The Australian HIV and sexually transmissible infection (STI) behavioural surveillance system (the repeated cross-sectional Gay Community Periodic Surveys, GCPS) has been conducted since 1998 and covers six main Australian jurisdictions. In this paper, we review its history and methodology, and the available indicators, their trends and their use., Methods: We describe the design and history of GCPS. For analyses of indicators, we use Pearson's χ²-test and test for trend where appropriate., Results: About 90% of gay men in Australia have been tested for HIV (60% to 70% of men who were not HIV-positive) have been tested as recommended in the preceding 12 months. STI testing levels (≈ 70% in the preceding 12 months) are high, but remain insufficient for STI prevention. In general, unprotected anal intercourse with regular (UAIR) and casual (UAIC) sex partners has increased over time. The prevalence and increasing trends in UAIR were similar across jurisdictions (P-trend <0.01), while trends in UAIC differed across the states: during 2001-08, UAIC declined in NSW (P-trend <0.01) and increased elsewhere (P-trend <0.01). Trends in UAIC were associated with HIV diagnoses., Conclusion: This review of the design, implementation and findings of the Australian HIV/STI behavioural surveillance highlights important lessons for HIV/STI behavioural surveillance among homosexual men, particularly the need for consistent data collection over time and across jurisdictions. Investment in systematic behavioural surveillance appears to result in a better understanding of the HIV epidemic, the availability of a warning system and a better targeted HIV prevention strategy.

Familiarity with and a history of prior sex with casual partners is associated with unprotected anal intercourse and may increase the risk of HIV transmission among gay men. Using data from the Sydney Gay Community Periodic Survey 2007, we explored the relationship between familiarity and unprotected anal intercourse with the last casual partner (UAI-LC). 51% of the men knew their last casual partner and 49% had previously had sex with him. Men were more inclined to engage in UAI-LC if they had previously had sex with this partner. HIV-negative men were more likely to have UAI-LC with a more familiar partner independent of his serostatus. Familiarity with and a previous history of sex between casual partners may result in a false sense of trust and may increase the risk of HIV transmission. HIV prevention services should address this issue and develop programs to improve men's skills in negotiating safer sex.

Prevalence of unprotected anal intercourse between casual male partners (UAIC) has been increasing worldwide. We explored trends in serodiscordant UAIC and the associated factors among gay men in Sydney. Proportions of HIV-positive and negative men with serodiscordant casual partners increased during 2003-2006. Prevalence of serodiscordant UAIC increased among HIV-negative men. Age, number of partners, seeking partners online, drug use and esoteric practices were associated with serodiscordant UAIC. Increases in serodiscordant UAIC may be related to growing disclosure. These findings do not indicate a core group of high-risk men. More research is needed about the context in which serodiscordant UAIC happens.

We explored seroguessing (serosorting based on the assumption of HIV seroconcordance) and casual unprotected anal intercourse (UAIC) associated with seroguessing. The ongoing Positive Health and Health in Men cohorts, Australia, provided data for trends in seroconcordant UAIC and HIV disclosure to sex partners. In event-level analyses, we used log-binomial regression adjusted for within-individual correlation and estimated prevalence rate ratios (PRRs) and 95% confidence intervals (95% CIs) for the association between the knowledge of a casual partner's seroconcordance and UAIC. UAIC and HIV disclosure significantly increased during 2001-2006. HIV-positive men knew partners were seroconcordant in 54% and assumed it in 13% of sex encounters (42 and 17% among HIV-negative men). Among HIV-positive men, the likelihood of UAIC was higher when a partner's status was known (Adjusted PRR = 5.17, 95% CI: 3.82-7.01) and assumed seroconcordant because of seroguessing (Adjusted PRR = 3.70, 95% CI: 2.56-5.35) compared with unknown. Among HIV-negative men, the likelihood of UAIC was also higher when a partner's status was known (Adjusted PRR = 1.88, 95% CI: 1.58-2.24) and assumed seroconcordant (Adjusted PRR = 2.12, 95% CI: 1.72-2.62) compared with unknown. As levels of UAIC remain high, seroguessing increasingly exposes gay men to the risk of HIV infection. Because both HIV-positive and HIV-negative men often seroguess, education and prevention programs should address the fact that HIV-negative men who engage in UAI due to this practice may be at high risk of HIV infection. HIV prevention should take into account these contemporary changes in behaviors, especially among HIV-negative gay men.

Objectives: We examined whether trends in HIV testing in community-based samples of homosexual men may account for the convergence in HIV notification rates in homosexual men across the eastern states of Australia., Methods: We examined data on self-reported HIV testing from annual cross-sectional, self-completed anonymous surveys of homosexual men conducted between 1998 and 2006 in Sydney, Melbourne and Brisbane. Men were recruited at gay community venues and events. Comparisons of HIV testing between the three cities and across time were carried out. We also compared reported rates of HIV testing across states in Private Lives, the 2005 online survey of health and wellbeing among non-heterosexual people., Results: Men recruited from clinics had a much higher prevalence of HIV testing and were excluded from further analyses. Among the 48 263 completed questionnaires obtained in non-clinic sites, there was a marked decline in the proportion of men who had never been tested for HIV in Sydney (from 8.1 to 5.1%, P trend < 0.001) and Brisbane (from 11.8 to 7.9%, P trend = 0.002) but no change in Melbourne. This proportion of men who had never been tested was lower in Sydney than in either Melbourne or Brisbane (P < 0.001). There were increases in the proportion of non-HIV-positive men who had been tested for HIV in the previous year across all three cities, although the proportion in Melbourne was lower than in the other two cities., Conclusion: These data suggest that changes in HIV testing rates among homosexual men are insufficient to account for the recent differences in trends in HIV notifications in eastern Australia.

Background: In Australia, the HIV epidemic is concentrated among gay men. In recent years, the number of new diagnoses stabilised in New South Wales (NSW), but increased in other states. We reviewed the trends in sexual behaviours to explain this difference., Methods: We used the Gay Community Periodic Surveys in NSW, Victoria and Queensland during 1998-2006 and restricted analyses to the 30-49 year olds who contribute most of the HIV cases. We used the chi(2)-test for trends in unprotected anal intercourse with casual partners (UAIC) and regular partners, number of partners, type of relationships, knowledge of HIV serostatus and its disclosure. We compared behaviours of HIV-positive and -negative men and men across states using logistic regression adjusted for the year of report., Results: Trends in behaviours differed across the states: following a period of increase, UAIC prevalence declined in NSW since 2001, but continued to increase in Victoria and Queensland. There were other changes in NSW that were not observed in Victoria and Queensland: a decline in factors increasing HIV risk (the proportions of men with multiple sex partners and men engaging in UAIC and not knowing or not disclosing HIV serostatus) and an increase in behaviours reducing it (the proportions of men in monogamous relationships and men disclosing HIV serostatus while having UAIC)., Conclusion: There were patterns of declining HIV risk behaviours in NSW, and increasing risk behaviours elsewhere, that mirrored recent changes in HIV case notifications in Australia. These data suggest that behavioural surveillance can predict changes in HIV epidemiology.