Effect of the revised AIDS case definition on AIDS reporting in San Francisco: evidence of increased reporting in intravenous drug users.

To examine the effect of the revision of the US national AIDS case definition in September 1987, we compared demographic and clinical information for AIDS patients diagnosed and reported to the San Francisco Department of Public Health between 1 September 1987 and 31 October 1989. Of the 3167 patients diagnosed and reported during the study period, 584 (18%) met the revised case definition only, increasing AIDS case reporting in San Francisco by 23%. One hundred and thirty-four of these 584 patients (23%) subsequently developed diagnoses meeting the old definition. After adjusting for this proportion, the revised case definition increased reporting by 17%. The mean time between initial diagnosis with a disease meeting the revised definition and subsequent development of a disease meeting the old definition was 18.5 months. Patients who met the revised case definition only were slightly older and more likely to be Black, female, and intravenous drug users (IVDUs) than those meeting the old case definition. The majority of patients who met the revised case definition only had initial diagnoses of HIV wasting syndrome (26%), HIV encephalopathy (21%), and presumptive Pneumocystis carinii pneumonia (19%). The revised AIDS case definition has significantly increased the reporting of severe morbidity associated with HIV infection, particularly among IVDUs.