AIDS incidence and income.

Since 1987, the annual increases of AIDS incidence among homosexual and bisexual men have slowed but the increases among other risk groups have continued unabated. Although indirect evidence suggests the incidence change is related to medical care for HIV disease delaying the onset of AIDS, other explanations are also possible. To examine the incidence change from a different perspective, we classified the residents of Philadelphia (PA, U.S.A.) with AIDS by the per capita income of their census tracts of residence. AIDS incidence increased steadily in the lowest income tercile, showed continuing but smaller increases after 1987 in the middle tercile, and was level after 1987 in the highest income tercile. The relationship between income and changes of incidence persisted after stratification on race or mode of infection with HIV. Income was associated with private medical insurance at the time of diagnosis of AIDS (59% privately insured in the highest income tercile, 24% in the lowest) and with median survival after a diagnosis of AIDS (467 days in the highest tercile of income, 359 days in the lowest). These observations are consistent with a medical treatment benefit that reaches the highest tercile of income and does not reach the lowest one.