The incidence and prevalence of AIDS and prevalence of other severe HIV disease in England and Wales for 1995 to 1999: projections using data to the end of 1994.

Abstract

Projections of the future incidence of AIDS cases are needed for planning purposes, to help set research priorities, and to describe the most likely pattern of transmission of HIV infection in the past that underlies the observed and projected incidence of AIDS. Earlier reports of projections for England and Wales were published in 1988, 1990, and 1993. During 1995 a group of experts has worked, using AIDS case reports to the end of December 1994, to make new projections to the end of 1999. The expert group concludes that, after adjustment for underreporting, there will be between 1840 and 2300 new cases of AIDS in England and Wales in 1997, and between 1760 and 2455 new AIDS cases in 1999. For planning purposes, a figure of 2025 new AIDS cases is projected for 1997, and 2010 for 1999. The planning projections for new AIDS cases in 1997 and 1999 among the main exposure categories, after adjustment for underreporting, are as follows: homo/bisexual males 1305 and 1235, people exposed heterosexually 490 and 525, and injecting drug users 140 and 155. Between 1995 and 1999, it is expected that new AIDS cases may fall by 7% in homo/bisexual males, and rise by 25% in the heterosexual exposure category and by 29% in injecting drug users. The incidence of AIDS in the children of mothers infected with HIV is expected to rise steadily from 30 new cases in 1994 to 45 in 1997 and 55 in 1999. New cases in recipients of contaminated blood or blood factors are expected to fall to 35 in 1997 and 30 in 1999, compared with a peak 10 years earlier of over 70 new cases each year. It is projected that 4010 AIDS cases will be alive in England and Wales at the end of 1999, and that the same number of people will be alive with other forms of severe HIV disease. Since 1989 the proportion of reported AIDS cases who live in the NHS Thames regions has remained constant at between 70% and 75%. We expect this concentration of AIDS cases in the south east, particularly within London, to remain unchanged. Compared with the report published in June 1993, the planning projections for 1997 are 37% lower for cases acquired heterosexually, and the upper boundary of the range in this exposure category has fallen from 1140 to 495. The reduction in the planning projection has resulted from a substantial decline in the rate of increase in the number of new AIDS cases arising each year from heterosexual exposure. The range of uncertainty has narrowed largely because more extensive seroprevalence data are now available. For homo/bisexual males, the planning projection for 1997 has fallen by 3%, because the 1993 report presented an over optimistic view of the extent to which patients received treatment and prophylaxis before the onset of AIDS, since such management became available in 1988. Unlike the 1993 working group, the 1995 working group has access to data from several years on the uptake of treatment and prophylaxis given before the diagnosis of AIDS. It is estimated that about 21,900 adults (range 20,400 to 23,400) were infected with HIV in England and Wales at the end of 1993. This total includes 12,350 who had been infected through male homosexual exposure, 2050 men and women infected through injecting drug use, 6800 men and women infected through heterosexual exposure, and about 3000 adults alive with AIDS. Various data indicate that HIV transmission among homo/bisexual men has been substantial since 1989. Use of data from the unlinked anonymous HIV prevalence monitoring programme suggest that between 500 and 1000 HIV infections due to homosexual male exposure occurred each year in 1992 and 1993. Should HIV transmission continue at this level, a high incidence of AIDS within the homo/bisexual male community will be inevitable for many more years. Most HIV infections and AIDS cases due to heterosexual exposure are thought to have been acquired abroad. The future of the epidemic in this exposure category is therefore unclear.