Estimating the Number of AIDS-Defining Opportunistic Illness Diagnoses From Data Collected Under the 1993 AIDS Surveillance Definition

Abstract
Expansion of the surveillance definition for AIDS in the United States in 1993 caused a substantial distortion in the trend in AIDS incidence, mainly because CD4-positive (CD4+) T-lymphocyte criteria were added to the definition. To evaluate trends in the rate at which HIV-infected persons develop the opportunistic illnesses listed in the AIDS surveillance definition (AIDS-OIs), we developed a procedure for estimating the incidence of these diseases. This estimate is based primarily on the probability distributions of the time from a CD4+ count in given ranges to the diagnosis of the first AIDS-OI. Our estimates of AIDS-OI incidence change by +