Fengyi Jin

Unprotected anal intercourse, risk reduction behaviours, and subsequent HIV infection in a cohort of homosexual men

Objective:A range of risk reduction behaviours in which homosexual men practise unprotected anal intercourse (UAI) has been described. We aimed to assess the extent of any reduction in HIV risk associated with these behaviours. Design:A prospective cohort study of HIV-negative homosexual men in Sydney, Australia. Methods:Men were followed up with 6-monthly detailed behavioural interviews and annual testing for HIV. The four risk reduction behaviours (behaviourally defined) examined were serosorting, negotiated safety, strategic positioning, and withdrawal during receptive UAI (UAI-R). Results:In 88% of follow-up periods in which UAI was reported, it occurred in the context of consistent risk reduction behaviours. Compared with those who reported no UAI, the risk of HIV infection was not raised in negotiated safety [hazard ratio = 1.67, 95% confidence interval (CI) 0.59–4.76] and strategic positioning (hazard ratio = 1.54, 95% CI 0.45–5.26). Serosorting outside negotiated safety was associated with an intermediate rate of HIV infection (hazard ratio = 3.11, 95% CI 1.09–8.88). Withdrawal was associated with a higher risk than no UAI (hazard ratio = 5.00, 95% CI 1.94–12.92). Patterns of UAI differed greatly according to partners serostatus. Men who reported serosorting were less likely to report either strategic positioning or withdrawal. Conclusion:Each behaviour examined was associated with an intermediate HIV incidence between the lowest and highest risk sexual behaviours. The inverse association between individual behaviours suggests that men who practise serosorting rely on this protection. The high prevalence of these behaviours demands that researchers address the contexts and risks associated with specific types of UAI.

Per-contact probability of HIV transmission in homosexual men in Sydney in the era of HAART.

Objective:The objective of this study is to estimate per-contact probability of HIV transmission in homosexual men due to unprotected anal intercourse (UAI) in the era of HAART. Design:Data were collected from a longitudinal cohort study of community-based HIV-negative homosexual men in Sydney, Australia. Methods:A total of 1427 participants were recruited from June 2001 to December 2004. They were followed up with 6-monthly detailed behavioral interviews and annual testing for HIV till June 2007. Data were used in a bootstrapping method, coupled with a statistical analysis that optimized a likelihood function for estimating the per-exposure risks of HIV transmission due to various forms of UAI. Results:During the study, 53 HIV seroconversion cases were identified. The estimated per-contact probability of HIV transmission for receptive UAI was 1.43% [95% confidence interval (CI) 0.48–2.85] if ejaculation occurred inside the rectum, and it was 0.65% (95% CI 0.15–1.53) if withdrawal prior to ejaculation was involved. The estimated transmission rate for insertive UAI in participants who were circumcised was 0.11% (95% CI 0.02–0.24), and it was 0.62% (95% CI 0.07–1.68) in uncircumcised men. Thus, receptive UAI with ejaculation was found to be approximately twice as risky as receptive UAI with withdrawal or insertive UAI for uncircumcised men and over 10 times as risky as insertive UAI for circumcised men. Conclusion:Despite the fact that a high proportion of HIV-infected men are on antiretroviral treatment and have undetectable viral load, the per-contact probability of HIV transmission due to UAI is similar to estimates reported from developed country settings in the pre-HAART era.

Gay men's current practice of HIV seroconcordant unprotected anal intercourse: serosorting or seroguessing?

Abstract 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 partners 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 partners 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 partners 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.

Incidence and risk factors for urethral and anal gonorrhoea and chlamydia in a cohort of HIV-negative homosexual men: the Health in Men Study

Background: Early detection and treatment of bacterial sexually transmitted infections has been advocated as an HIV prevention strategy. Aim: To inform screening guidelines, the incidence and risk factors for urethral and anal gonorrhoea and chlamydia were studied in a prospective cohort of community-based HIV negative homosexual men in Sydney, New South Wales, Australia. Methods: All participants were offered annual screening for gonorrhoea and chlamydia (study-visit diagnoses) on urine and anal swabs using nucleic acid amplification. Participants also reported diagnoses of gonorrhoea and chlamydia made elsewhere between interviews (interval diagnoses). All diagnoses were summed to create a combined incidence rate, and detailed data on specific sexual practices with casual and regular partners were collected. Results: Among 1427 men enrolled, the combined incidence rates were 3.49 and 2.96 per 100 person-years for urethral and anal gonorrhoea, respectively; and 7.43 and 4.98 per 100 person-years for urethral and anal chlamydia, respectively. Urethral infections were associated with unprotected anal intercourse (UAI) with HIV-positive partners (hazard ratio (HR) = 2.58, 95% CI 1.10 to 6.05 for urethral gonorrhoea) and with frequent insertive oral sex (p for trend 0.007 for urethral chlamydia). Anal infections were associated with receptive UAI (p for trend 0.001 for both anal gonorrhoea and chlamydia) and other receptive anal sexual practices. Stratified analyses showed the independence of the associations of insertive oral sex with urethral infections and of non-intercourse receptive anal practices with anal infections. Conclusion: Incident gonorrhoea and chlamydia were common. Risk behaviours for both urethral and anal infections were not restricted to UAI. Screening that includes tests for anal and urethral infections should be considered for all sexually active homosexual men, not just for those who report UAI.

Cancers attributable to human papillomavirus infection.

Although the human papillomavirus (HPV) vaccine was introduced primarily as a cervical cancer prevention vaccine, HPV has a causal role in several types of cancer. This article reviews the epidemiological evidence for the role of HPV in human cancer, and describes Australian trends in these cancers. HPV is a necessary cause of cervical cancer. The currently vaccine-preventable subtypes of HPV 16 and 18 are responsible for ~70% of cervical cancer. The introduction of an organised Pap smear program in Australia led to a steep decline in incidence over the past decades. HPV can be detected in ~40% and 70% of vulval and vaginal cancers respectively. Rates of these cancers have been stable over the past 20 years. The prevalence of HPV in penile cancer is ~50% and incidence has not recently changed. For anal cancer, ~85% of cases are HPV positive, and incidence has increased significantly in both men and women over the past 20 years. In the oral cavity, ~35% of oropharyngeal cancers and ~25% of other oral cavity cancers are HPV positive. The incidence of HPV-related oral cavity and oropharyngeal cancers is increasing, whereas incidence at HPV-unrelated sites is decreasing. Overall, 1154 HPV-related cancer cases were potentially preventable by vaccination. If HPV-related cancers at non-cervical sites are prevented by vaccination, then a similar number of cancer cases will be prevented as in the cervix. However, almost one-quarter of the potentially preventable cancer cases are in men, who are not included in the current national immunisation program.

Predictors of recent HIV testing in homosexual men in Australia.

To describe time trends and other predictors of recent HIV testing among homosexual men enrolled in behavioural surveillance studies in Australia.

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.

High rates of sexually transmitted infections in HIV positive homosexual men: data from two community based cohorts

Background/objectives: Higher levels of sexual risk behaviours have been reported in HIV positive than in HIV negative homosexual men. In clinic based studies, higher rates of sexually transmitted infections (STIs) have also been reported. We compared rates of common STIs between HIV positive and HIV negative homosexual men from two ongoing community based cohort studies in Sydney, Australia. Methods: Participants in the two cohorts were recruited using similar community based strategies. They were interviewed face to face annually after enrolment. Comprehensive sexual health screening, including hepatitis A and B, syphilis, gonorrhoea, and chlamydia (in urethra and anus) was offered to participants in both cohorts. Results: In participants in the HIV positive cohort, 75% were hepatitis A seropositive, 56% had serological evidence of previous or current hepatitis B infection, and 24% had evidence of vaccination against hepatitis B infection. 19% of men tested positive for syphilis and 4% had evidence of recent infections. Compared with men in the HIV negative cohort, after adjustment for age, HIV positive participants had significantly higher prevalence of previous or current hepatitis B infection, syphilis, and anal gonorrhoea. Conclusion: This finding supports the need for frequent STI testing in HIV positive men to prevent morbidity and to decrease the risk of ongoing HIV transmission.

Anal sexually transmitted infections and risk of HIV infection in homosexual men.

Background:We examined a range of common bacterial and viral sexually transmitted infections as risk factors for HIV seroconversion in a community-based cohort of HIV-negative homosexual men in Sydney, Australia. Methods:Detailed information about HIV risk behaviors was collected by interview twice yearly. Participants were tested annually for HIV, anal and urethral gonorrhea and chlamydia, herpes simplex virus types 1 and 2, and syphilis. In addition, they reported annual diagnoses of these conditions and of genital and anal warts. Results:Among 1427 enrolled participants, 53 HIV seroconverters were identified, giving an incidence of 0.78 per 100 person-years. After controlling for number of episodes of insertive and receptive nonseroconcordant unprotected anal intercourse, there were independent associations with anal gonorrhea (adjusted hazard ratio = 7.12, 95% confidence interval: 2.05 to 24.79) and anal warts (hazard ratio = 3.63, 95% confidence interval: 1.62 to 8.14). Conclusions:Anal gonorrhea and anal warts were independently associated with HIV acquisition. The added HIV prevention value of more frequent screening of the anus to allow early detection and treatment of anal sexually transmitted infections in homosexual men should be considered.

Trends in anal cancer in Australia, 1982–2005

BACKGROUND Most anal squamous cell carcinomas (SCCs) are caused by high risk types of human papillomavirus (HPV) and are potentially preventable by HPV vaccination. In order to understand the burden of potentially preventable anal cancer in Australia, we examine the incidence and survival from invasive anal SCC 1982-2005. METHODS We reviewed data on invasive anal cancer cases notified to the National Cancer Statistics Clearing House. Age specific incidence rates of SCC were calculated by year of cancer diagnosis and by birth cohort, and rates of anal adenocarcinoma were included for comparison. Incidence rates were age standardised to the Australian 2001 standard population. Trends in relative survival of SCC were examined. RESULTS During the study period, a total of 4615 invasive anal cancer cases were diagnosed and most (69.7%) were SCC. Annual incidence of SCC increased almost 50%, from 0.65 to 1.00/100,000. Incidence increased at all ages. The annual rate of increase was almost two-folder higher in men (3.42%, 95% CI 2.49-4.35) than in women (1.88%, 95% CI 1.18-2.58). Five-year relative survival increased by nearly 10% from 58.9% to 68.3% over the last 20 years. Younger patients and women had better survival. For anal adenocarcinoma, increases of borderline significance were seen in men and women. CONCLUSION There is an increasing burden of anal SCC in Australia. The group with the highest incidence - homosexual men - are not likely to be protected under the current vaccination policy.