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FORECASTING THE FUTURE OF AIDS.

Although the number of new AIDS cases continues to increase each year, some signs suggest that the epidemic may have peaked in certain groups. The difficulty of using this information to predict the future of the AIDS epidemic -- and thus to plan for health-care needs -- is reflected in a series of recent articles in JAMA.

Lemp and colleagues describe a model that predicts the expected morbidity and mortality from AIDS in San Francisco. The model uses data on seroconversion rates for homosexual and bisexual men and intravenous drug abusers, assuming a median incubation period for AIDS among infected persons of 11 years and a median survival after diagnosis of 14.4 months. These authors concluded that annual mortality will continue to rise, reaching 1388 to 2478 deaths per year in 1993 in San Francisco alone.

In contrast, Bregman and Langmuir examined the AIDS epidemic using Farr's Law, which dictates that in large epidemics the incidence of cases tends to rise and then fall in the shape of a normal curve. Their analysis indicates that the incidence of AIDS peaked in late 1988 and will decline to a low point by the mid-1990s.

In an accompanying editorial, Morgan questions whether Farr's Law is appropriate for HIV, which infects subsets of people in different ways at different rates, and suggests that Bregman and Langmuir may be underestimating the cumulative number of AIDS cases to come.

— THL

Published in Journal Watch General Medicine March 20, 1990

Citation(s):

Morgan M et al. The future course of AIDS in the United States. JAMA 1990 Mar 16 263 1539-1540.

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Bregman DJ; Langmuir AD. Farr's Law applied to AIDS projections. JAMA 1990 Mar 16 263 1522-1525.

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Lemp GF et al. Projections of AIDS morbidity and mortality in San Francisco. JAMA 1990 Mar 16 263 1497-1501.

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