Projection of AIDS morbidity and mortality in San Francisco

The increase in new cases of AIDS (acquired immunodeficiency syndrome) has become a primary focus of concern for public health services in this country. Methods for reliably predicting new cases are needed to anticipate the medical care that will be required for these patients. A predictive model for AIDS has been developed using annual rates of human immunodeficiency virus (HIV) seroconversion (detection of HIV antibodies in the blood) for homosexual and bisexual men and for heterosexual intravenous drug users. Estimates were made using the size of the high risk population and the duration of HIV infection to predict morbidity in San Francisco, CA through June of 1993. The incubation period for the development of AIDS in those who were HIV-positive was ascertained and used as a key parameter; the course of AIDS is known to depend upon the length of infection. Mortality was predicted by using Kaplan-Meier estimates of survival time after initial diagnosis and the projected number of new cases. Data were collected beginning in 1978; the future effects of antiviral therapies, which most likely will be forthcoming, or of earlier treatments on survival rates were not factored into these figures. The median incubation period for AIDS was estimated to be 11.0 years. Based on this model, the number of new AIDS cases in San Francisco by 1993 is expected to be between 12,349 and 17,022, with between 9,966 and 12,767 cumulative deaths. Since 1983, a decline in seroconversion rates has occurred among the San Francisco population of homosexual and bisexual men. Conversely, the number of seroconversions for heterosexual intravenous drug users is expected to increase by about three percent annually through 1993. (Consumer Summary produced by Reliance Medical Information, Inc.)