Direct estimates of prevalent HIV infection in adults in England and Wales for 1991 and 1993: an improved method

Association between fertility and HIV status: what implications for HIV estimates?

BACKGROUND

Most estimates of HIV prevalence have been based on sentinel surveillance of pregnant women which may either under-estimate or over-estimate the actual prevalence in adult female population. One situation which can lead to either an underestimate or an overestimate of the actual HIV prevalence is where there is a significant difference in fertility rates between HIV-positive and HIV-negative women. Our aim was to compare the fertility rates of HIV-infected and HIV-uninfected women in Cameroon in order to make recommendations on the appropriate adjustments when using antenatal sentinel data to estimate HIV prevalence.

METHODS

Cross-sectional, population-based study using data from 4493 sexually active women aged 15 to 49 years who participated in the 2004 Cameroon Demographic and Health Survey.

RESULTS

In the rural area, the age-specific fertility rates in both HIV positive and HIV negative women increased from 15-19 years age bracket to a maximum at 20-24 years and then decreased monotonically till 35-49 years. Similar trends were observed in the urban area. The overall fertility rate for HIV positive women was 118.7 births per 1000 woman-years (95% Confidence Interval [CI] 98.4 to 142.0) compared to 171.3 births per 1000 woman-years (95% CI 164.5 to 178.2) for HIV negative women. The ratio of the fertility rate in HIV positive women to the fertility rate of HIV negative women (called the relative inclusion ratio) was 0.69 (95% CI 0.62 to 0.75).

CONCLUSION

Fertility rates are lower in HIV-positive than HIV-negative women in Cameroon. The findings of this study support the use of summary RIR for the adjustment of HIV prevalence (among adult female population) obtained from sentinel surveillance in antenatal clinics.

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.

Estimating adult HIV prevalence in the UK in 2003: the direct method of estimation

BACKGROUND

Estimates of the total number of prevalent HIV infections attributable to the major routes of infection make an important contribution to public health policy, as they are used for planning services.

METHODS

In the UK, estimates were derived through the "direct method" which estimated the total number of diagnosed and undiagnosed HIV infections in the population. The direct method has been improved over a number of years since first used in 1994, as further data became available such as the inclusion of newly available behavioural survey data both from the National Survey of Sexual Attitudes and Lifestyles (Natsal 2000) and community surveys of men who have sex with men (MSM). These data were used to re-estimate numbers of people unaware of their infection and provided ethnic breakdowns within behavioural categories. The total population was divided into 10 mutually exclusive behavioural categories relevant to HIV risk in the UK-for example, MSM and injecting drug users. Estimates of the population size within each group were derived from Natsal 2000 and National Statistics mid-year population estimates. The total number of undiagnosed HIV infections was calculated by multiplying the undiagnosed HIV prevalence for each group, derived from the Unlinked Anonymous HIV Prevalence Monitoring Programme surveys (UAPMP), by the population size. These estimates were then added to the prevalent diagnosed HIV infections within each group derived from the national census of diagnosed HIV infections, the Survey of Prevalent HIV Infections Diagnosed (SOPHID). The estimates were then adjusted to include all adults in the UK. Because undiagnosed HIV prevalence estimates were not available for each of the behavioural categories, the UAPMP prevalence estimates were adjusted using available data to provide the best estimates for each group.

RESULTS

It is estimated that 53,000 individuals are infected with HIV in the UK in 2003, of whom 27% were unaware of their infection. Of the total of 53,000, an estimated 26,000 were among heterosexually infected and 24,500 among MSM.

CONCLUSION

The direct method uses an explicit framework and data from different components of the HIV surveillance system to estimate HIV prevalence in the UK, allowing for a comprehensive picture of the epidemic.

Improving analysis of the size and dynamics of AIDS epidemics

Supplement editors Peter D Ghys and Neff Walker and the Chair of the UNAIDS Reference Group on Estimates, Modelling and Projections, Geoff P Garnett, introduce 13 papers describing the data, methods, and tools used to produce the 2005 UNAIDS/WHO HIV and AIDS estimates

Recent trends in HIV and other STIs in the United Kingdom: data to the end of 2002

Sexual health in the United Kingdom has deteriorated in recent years with further increases in HIV and other sexually transmitted infections (STIs) reported in 2002. This paper describes results from the available surveillance data in the United Kingdom from the Health Protection Agency and its national collaborators. The data sources range from voluntary reports of HIV/AIDS from clinicians, CD4 cell count monitoring, a national census of individuals living with HIV, and the Unlinked Anonymous Programme, to statutory reports of STIs from genitourinary medicine (GUM) clinics and enhanced STI surveillance systems. In 2002, an estimated 49500 adults aged over 15 years were living with HIV in the United Kingdom, of whom 31% were unaware of their infection. Diagnoses of new HIV infections have doubled from 1997 to 2002, mainly driven by heterosexuals who acquired their infection abroad. HIV transmission also continues within the United Kingdom, particularly among homo/bisexual men who, in 2002, accounted for 80% of all newly diagnosed HIV infections acquired in the United Kingdom. New diagnoses of syphilis have increased eightfold, and diagnoses of chlamydia and gonorrhoea have doubled from 1997 to 2002 overall; STI rates disproportionately affect homo/bisexual men and young people. Effective surveillance is essential in the provision of timely information on the changing epidemiology of HIV and other STIs; this information is necessary for the targeting of prevention efforts and through providing baseline information against which progress towards targets can be monitored.

Oral examination: a screening tool for HIV infection?

OBJECTIVE

To estimate the predictive values for HIV infection of diagnosis of oral manifestations of the infection.

METHOD

Prevalence of oral manifestations was compared in cross sectional blinded clinical examinations of homosexual men attending a genitourinary medicine clinic. Data were extrapolated to populations in England and Wales based on estimates of the prevalence of HIV infection.

RESULTS

Data were analysed for 572 HIV infected and non-infected men (312 and 260 respectively). Positive predictive values for erythematous candidiasis, hairy leucoplakia and pseudomembranous candidiasis were greater than 0.96 at the genitourinary medicine clinic and are estimated to be greater than 0.72 among homosexual men in London.

CONCLUSIONS

Clinical diagnoses of mucosal lesions alone are poor predictors of HIV infection but are useful when used in conjunction with a social history to establish if there are risk factors for infection.