AIDS prevalence by income group in Philadelphia.

We sought to track recent changes in AIDS incidence and prevalence in the city of Philadelphia (PA, U.S.A.) using morbidity and mortality data reported to the health department. We stratified the data by the mean per capita income in census tracts where people with AIDS resided. Estimates made without adjustment for the time lag between events and their entry into the database undercount both recent AIDS diagnoses and recent AIDS deaths. Therefore, we used a previously published method to adjust for the lag in reporting diagnoses and developed a method to adjust for the lag in reporting deaths. We calculated prevalent cases as the difference between cumulative cases and cumulative deaths. Between 1988 and 1990, annual AIDS incidence per 100,000 Philadelphia residents increased by 21% (from 25.9 to 31.4) and AIDS prevalence per 100,000 population increased by 62% (from 30.2 to 48.8). AIDS prevalence increased 113% (from 29.8 to 63.6) in low-income tracts, 88% (from 27.8 to 52.3) in middle-income tracts, and 14% (from 32.5 to 37.2) in high-income tracts. The 62% increase in AIDS prevalence and the shift toward people in poorer neighborhoods imply a need for public funding for AIDS care that is far larger than would be suggested by the general 21% increase in AIDS incidence over the same period.