Incidence of HIV infection in homosexual men in London, 1988-94

HIV in gay and bisexual men in the United Kingdom: 25 years of public health surveillance

It is more than 25 years since the first case of AIDS was reported in the United Kingdom. In December 1981 a gay man was referred to a London hospital with opportunistic infections indicative of immunosuppression. National surveillance began the following year, in September 1982, with the notification of deaths and clinical reports of AIDS and Kaposi's sarcoma plus laboratory reports of opportunistic infections. Since then epidemiological surveillance systems have evolved, adapting to, and taking advantage of advances in treatments and laboratory techniques. The introduction of the HIV antibody test in 1984 led to the reporting of HIV-positive tests by laboratories and the establishment of an unlinked anonymous survey in 1990 measuring undiagnosed HIV infection among gay men attending sexual health clinics. The widespread use of highly active antiretroviral therapies (HAART) since 1996 has averted many deaths among HIV-positive gay men and has also resulted in a large reduction in AIDS cases. This led to a need for an enumeration of gay men with HIV accessing NHS treatment and care services (1995 onwards), more clinical information on HIV diagnoses for epidemiological surveillance (2000 onwards) and the routine monitoring of drug resistance (2001 onwards). Twenty-five years after the first case of AIDS was reported, gay and bisexual men remain the group at greatest risk of acquiring HIV in the United Kingdom. Latest estimates suggest that in 2004, 26 500 gay and bisexual men were living with HIV in the United Kingdom, a quarter of whom were undiagnosed. In this review, we examine how national surveillance systems have evolved over the past 25 years in response to the changing epidemiology of HIV/AIDS among gay and bisexual men in the United Kingdom as well as advances in laboratory techniques and medical treatments. We also reflect on how they will need to continue evolving to effectively inform health policy in the future.

Time trends in HIV incidence among homosexually active men seen at sexual health clinics in Australia, 1993-1999

BACKGROUND

Increases in sexual risk behaviour have recently been reported among homosexually active men in Australia and in other industrialised countries, potentially facilitating an increase in HIV incidence.

OBJECTIVE

To monitor HIV incidence among homosexually active men seen through a network of sexual health clinics in Australia.

STUDY DESIGN

Selected metropolitan public sexual health clinics provided counts of the number of people seen at the clinics during a calendar year, the number voluntarily tested for HIV antibody and the number newly diagnosed with HIV infection, broken down by sex, age group, HIV exposure category and HIV antibody testing history. HIV incidence was estimated among homosexually active men with a history of a negative test in the 12 months prior to last being seen in a calendar year.

RESULTS

Of 23924 men seen at the clinics in 1993-1999 with a reported history of male homosexual contact, 7440 (31.1%) had a negative test in the 12 months prior to last being seen in a calendar year. The percentage of men with a recent negative test declined significantly over time, from more than 33% in 1994-1996 to 29% in 1999 (P=0.003), and with increasing age, from 34.3% among men aged 25-29 years to 27.4% among men aged 40 years or older (P<0.0005). A total of 5346 (71.9%) men were retested for HIV antibody within 12 months of the last negative test. The percentage of men retested declined significantly over time, from 77.8% in 1994 to 67.2% in 1999 (P=0.021) but did not change by age group (P=0.132). Overall, 56 men were newly diagnosed with HIV infection. Estimated HIV incidence was 2.1% in 1993-1999; incidence did not change significantly by year (P=0.498) or age group (P=0.757).

CONCLUSION

HIV incidence has remained stable among homosexually active men seen through a network of sexual health clinics in Australia.

HIV surveillance among men who have sex with men

OBJECTIVES

To review current approaches to HIV surveillance among men who have sex with men (MSM), identify illustrative best practices and lessons learned, and outline ways to enhance surveillance systems.

METHODS

Review of the literature and institutional guidelines for HIV/AIDS, sexually transmitted infection (STI), and behavioral surveillance and summary of results of an international workshop.

RESULTS

On-going formative research, HIV/AIDS and STI case reporting, HIV prevalence and incidence studies, and behavioral surveys are essential components of an effective HIV surveillance system for MSM. Alliances with key organizations and actors in MSM communities provide points of access, assist in the development of measures, and guide appropriate use of data. Sampling techniques (convenience, snowball, quota, microsite, time-location, and population-based) offering a range of methods, complexity, and cost have been successfully implemented in MSM communities. Plausible estimates of the size of MSM populations, which are ultimately crucial to the interpretation of surveillance data, can be improved upon using primary and secondary data.

CONCLUSIONS

The purpose of HIV surveillance among MSM is not only to monitor disease occurrence and its antecedents, but to regularly use data to plan and evaluate prevention and care programs, advocate for prevention resources, and improve the health, social welfare and human rights of MSM. Practical, incremental steps can be taken to improve HIV surveillance among MSM in all regions of the world in all stages of the epidemic.

Surveillance for incident HIV infection: new technology and new opportunities

Although surveillance for HIV infection has traditionally focused on the incidence of AIDS and the prevalence of HIV, new diagnostic technologies that allow the estimation of incident HIV infection have become available. Number and distribution of new cases of HIV infection, rather than old cases, are the data most relevant to guide rational application of HIV prevention programs. Historically, incident HIV infection has been measured in longitudinal cohort studies, diagnosed clinically or since 1993 by detection of seroconverting patients (during the window period before appearance of HIV antibody) who are viremic as measured by p24 antigen or RNA-PCR. The sensitive-less sensitive EIA test (or serologic testing algorithm for recent HIV seroconversion [STAHRS]) has now made the serologic diagnosis of incident HIV infection in individual patients as well as the estimation of HIV incidence in populations possible. Examples of the public health application of this are studies of HIV incidence in anonymous test site attendees, sexually transmitted disease clinic patients, and in-treatment injection drug users in San Francisco. These sorts of studies allow us not only to measure incidence cross-sectionally but also facilitate surveillance for HIV subtypes and primary antiretroviral resistance, targeting early antiretroviral therapy and partner notification, and understanding who is "failing" prevention. Having an HIV surveillance system that focuses on incident rather than prevalent infection should be our long-term goal.

What a test for recent infection might reveal about HIV incidence in England and Wales

BACKGROUND

A laboratory method has been developed that detects recent HIV infection and allows incidence to be estimated by testing single stored antibody-positive specimens. A theoretical exploration of the method's surveillance utility was carried out.

METHODS

Using various data sources, HIV incidence rates were postulated. The confidence intervals (CI) for these postulated incidences were calculated using the expected number of recent infections for each postulated incidence, the actual number tested for HIV, and the known number of HIV-1 positives. A test for trend was used to determine when an important change in incidence could be recognized.

RESULTS

If the incidence was 5% per annum (p.a.) in homosexual/bisexual men attending sexually transmitted diseases (STD) clinics in London, 64 recent infections would be expected in the 392 HIV-seropositive specimens and, if observed, would result in a 95% CI of 3.1-7.9% p.a. for the incidence rate. An incidence of 1% p.a. in pregnant women would be most unlikely as this would require detection of 193 recent infections, 26 more than the total 167 HIV-seropositive specimens found in 1997. In African women attending STD clinics in London, 30% of prevalent infections would be classified as recent if the incidence was 5% p.a. Further, if the incidence in homosexual/bisexual men were to fall by 50% over 3 years, a decrease of this magnitude would be recognized as significant within 2 years.

CONCLUSIONS

The detuned assay will increase the information from HIV serosurveys even where prevalence and incidence are relatively low. Existing surveillance systems should be redesigned to take full advantage of the method.

Trends in undiagnosed HIV-1 infection among attenders at genitourinary medicine clinics, England, Wales, and Northern Ireland: 1990-6

OBJECTIVE

To describe trends in seroprevalence of undiagnosed HIV-1 infection among attenders at 15 genitourinary medicine clinics in England, Wales, and Northern Ireland between 1990 and 1996.

METHOD

Prospective, cross sectional sentinel serosurvey. Unlinked anonymous testing of remnant serum drawn for routine syphilis screening.

RESULTS

In 1996, the seroprevalence of undiagnosed HIV-1 infection was 5% in homosexual men, 0.48% in heterosexual men, and 0.33% in heterosexual women. Between 1990 and 1996, there was a significant linear decrease in the seroprevalence of undiagnosed HIV-1 infection among homosexual and bisexual men within and outside London (p < 0.0001; p = 0.0141), equivalent to yearly decreases of 7.65% and 10.73% respectively. However, seroprevalence among homosexual and bisexual men under 25 years of age did not decline either inside or outside London. Seroprevalence among heterosexual men declined outside London (p < 0.005), equivalent to an average annual decrease of 14.54%. There was a significant increase among male heterosexuals inside London (p < 0.05) equivalent to a 8.09% increase per annum. Seroprevalence over time was unchanging among female heterosexuals both inside and outside London. Seroprevalence was significantly higher among those who injected drugs than those who did not report injecting in the following groups: homosexual and bisexual males within London (p < 0.005), male heterosexuals both within and outside London (p < 0.05; p < 0.05) and female heterosexuals within London (p < 0.05).

CONCLUSIONS

The study highlights a significant burden of undiagnosed HIV-1 infection more than 15 years since the HIV epidemic began. Methods of offering HIV testing need to be reassessed to extend the practice of routinely testing for HIV in GUM clinics. HIV transmission among young homosexual and bisexual men continues. The contrasting trends between homosexual and bisexual men, injecting drug users, and heterosexuals attending GUM clinics indicate these groups should be considered separately. The substantial HIV seroprevalence in each group indicates that they should be priorities for targeted HIV prevention.

Interval-censored survival data with informative examination times: parametric models and approximate inference

We develop parametric methods for analysing interval-censored data when examination and survival times are not independent. The hazard function is modelled by introducing individual frailties related to the frequency of examinations. Model parameters may be obtained by direct maximization of the marginal log-likelihood. We develop a simpler approximate method in which the frailties are estimated by empirical Bayes. The two approaches are equivalent asymptotically as the number of examinations on each individual increases. Simulations suggest that the approximate method is adequate for estimating regression parameters even when the number of examinations on each individual is small. The methods are used to estimate age and period effects on HIV incidence in a cohort of repeat attenders at genito-urinary clinics in London, U.K.

Evaluation of behavioural interventions in HIV/STI prevention

There is an urgent need for well designed randomised trials to assess the impact of behavioural interventions at both individual and community levels in developed and developing countries. The relative lack of such studies partly reflects the particular challenges of applying randomised trials in this area. Although there are obvious differences between clinical and behavioural interventions, the principles underlying successful evaluation are not fundamentally different. Experience gained from clinical trial methodology over the past two decades should be applied and further developed to tackle the demands and challenges of evaluating behavioural interventions in HIV/STI prevention.

HIV seroincidence and risk factors among patients repeatedly tested for HIV attending sexually transmitted disease clinics in the United States, 1991 to 1996. STD Clinic HIV Seroincidence Study Group

To assess the incidence of HIV infection and risk factors associated with HIV seroconversion among patients attending clinics for sexually transmitted diseases (STD), medical record reviews were conducted in 12 clinics in 7 U.S. cities. The records of all patients who initially tested negative for HIV from 1991 through 1996 and who received at least one additional HIV test during the study period were reviewed. In each of 7 cities, 5 to 112 patients seroconverted. Of the 286 seroconverters identified in total, 53% (152 of 286) were heterosexual men and 28% (81 of 286) were women. HIV incidence rates among men who have sex with men (MSM) ranged by city from 0.81 to 7.0 new infections/100 person-years. Rates among heterosexual men and women ranged from 0.018 to 1.2 infections/100 person-years. Multivariate analyses showed that drug use was associated with HIV seroconversion only among heterosexuals. Most new HIV infections in these clinics are being transmitted heterosexually and are associated with drug use. Nevertheless, MSM, particularly young MSM, are at greatest risk for HIV in this population: 1 of 47 seroconvert/year. The effective use of targeted prevention efforts depends upon the continued ability to monitor the incidence of HIV infection.

Surveillance of sexual behaviour among homosexual men in a central London health authority

OBJECTIVE

To establish a surveillance mechanism of high risk sexual behaviour among homosexual and bisexual men living, socialising and using services in a central London health authority.

DESIGN

Baseline survey for a system of repeatable behavioural surveillance using a self-completed questionnaire delivered by healthcare providers.

SETTING

Genitourinary medicine clinics, gay bars, clubs, community groups and a cruising ground in the defined geographical area of a central London health authority.

PARTICIPANTS

Five hundred and fifty three homosexual and bisexual men.

MAIN OUTCOME MEASURES

Self-reported behaviours including unprotected anal intercourse (UAI), HIV status of unprotected anal intercourse partners, uptake of HIV testing and use of condoms at first time of anal intercourse.

RESULTS

Five hundred and sixty questionnaires were returned (response rate 76%) from 553 men. A third (35%) of men surveyed had had UAI in the previous year. Nearly a fifth (19%) of the sample had had UAI with one or more partners of a discordant or unknown HIV status. A total of 343 (63%) men had had an HIV test. The proportion of men using condoms on the occasion of first anal intercourse has risen from 6% before 1980 to 88% after 1993.

CONCLUSIONS

We have demonstrated that a surveillance programme to monitor high risk sexual behaviour among homosexual men can be easily established. The results can be employed to assess progress towards risk reduction targets and also inform future policy development. Our baseline data demonstrate that a large proportion of homosexual men are continuing to engage in high risk sexual behaviour, although there is some evidence of improvement in condom use at first anal intercourse over time. There is a need for continuing health promotion with evaluation among homosexual men.

Age-specific HIV incidence among homosexually active men in Australia

OBJECTIVE

To estimate age at HIV infection among homosexually active men in Australia.

DESIGN

Age-specific back-projection estimates of HIV incidence.

METHODS

Monthly counts of AIDS among homosexually active men diagnosed by 30 June 1994 and reported by 31 March 1995 were obtained from the National AIDS Registry and were adjusted for reporting delays. The progression rate to AIDS was estimated from a large cohort study of HIV-infected homosexual men, with adjustment for the effect of age at HIV infection and the effect of antiretroviral and prophylactic treatments.

RESULTS

The median age at HIV infection was estimated to have decreased from 31 years of age between 1982 and 1984 to between 23 and 27 years in the periods 1987 to 1989 and 1990 to 1994. Despite the trend to a younger median age at HIV infection during the current epidemic, HIV incidence was estimated to have declined in all age groups from a peak in the mid-1980s. This decline was more pronounced in the older age groups, with more modest reductions in age groups under 30 years.

CONCLUSION

Most HIV infections among homosexually active men since 1987 appear to have occurred in men aged under 30 years. This has implications for education programs aimed at preventing HIV infection among homosexually active men.

A case control study of HIV seroconversion in gay men, 1988-1993: what are the current risk factors?

OBJECTIVE

To investigate current risk factors for HIV seroconversion among homo/bisexual men.

DESIGN

Matched case control study in a large STD clinic in central London. Data on risk factors were obtained by case note review.

METHODS

Fifty-six cases who had at least one negative HIV test followed by a positive test between June 1988 and July 1993, and two homo/bisexual controls (having two or more negative HIV tests) matched to each case on age, total number of HIV tests and test interval period were identified. Univariate and multivariate odds ratio were calculated for acute STD, ano-genital intercourse, condom use and HIV status of sexual partners.

RESULTS

Adjusted odds ratios (95% confidence intervals) for HIV seroconversion were 4.1 (1.3-13.3) for having an acute interval STD and 4.6 (1.4-15.4) for having a known HIV infected sexual partner. Compared with men who always used condoms, odds ratios for men who sometimes or never used condoms were 7.9 (2.2-28.9) and 16.2 (3.0-86.0) respectively. Unprotected ano-genital intercourse was commonly reported by both cases and controls, and reported condom use was no greater with a known HIV infected partner than with a partner of unknown HIV status.

CONCLUSION

HIV seroconversion among homo/bisexual men attending STD clinics is strongly related to having an acute STD, a known HIV infected partner and not using condoms. Although consistent use of condoms is highly protective, knowing that a partner is HIV infected does not ensure condom use between serodiscordant men. More effective, well-evaluated interventions are needed to reduce sexual risk-taking in this population.

Continuing transmission of sexually transmitted diseases among patients infected with HIV-1 attending genitourinary medicine clinics in England and Wales

OBJECTIVE

To determine whether those who are aware of being infected with HIV continue to adopt behaviours that place others at risk of HIV infection.

DESIGN

Ongoing survey of current diagnosis of sexually transmitted disease and awareness of HIV infection among patients attending genitourinary medicine clinics.

SETTING

Six genitourinary medicine clinics in England and Wales (two in London and four outside) participating in unlinked anonymous HIV serosurveillance during 1990-3.

SUBJECTS

All attenders having blood drawn for syphilis serology for the first time during the calendar quarter of attendance.

MAIN OUTCOME MEASURES

The proportion of syphilis serology specimens with antibody to HIV-1 detected by unlinked anonymous testing of the residue. The proportion of attenders infected with HIV-1 who remained clinically undetected, and the proportion who had another recently acquired sexually transmitted disease.

RESULTS

Of 85441 specimens tested, 2328 (2.7%) were positive for antibodies to HIV-1. About 30% of these specimens were from attenders whose HIV-1 infection remained clinically undetected. HIV-1 infection was found to coexist with another recently acquired sexually transmitted disease in 651 attenders, of whom 522 were homosexual or bisexual men. Of these, 245 (47%) already knew themselves to be infected with HIV-1. This proportion increased between 1990 and 1993.

CONCLUSIONS

A considerable proportion of patients infected with HIV-1 are not identified by voluntary confidential HIV testing in genitourinary medicine clinics. Substantial numbers of homosexual or bisexual men attending genitourinary medicine clinics continue to practise unsafe sex despite being aware of their infection with HIV-1.