A New Preadmission Staging System for Predicting Inpatient Mortality from HIV-associated Pneumocystis Carinii Pneumonia in the Early Highly Active Antiretroviral Therapy (HAART) Era

A common severe complication of human immunodeficiency virus (HIV) infection has been Pneumocystis carinii pneumonia (PCP). Recently, with increasing use of PCP prophylaxis and multidrug antiretroviral therapy, the clinical manifestations of HIV infection have changed dramatically and the predictors of inpatient mortality for PCP may have also changed. We developed a new staging system for predicting inpatient mortality for patients with HIV-associated PCP admitted between 1995 and 1997. Trained abstractors performed chart reviews of 1,660 patients hospitalized with HIV-associated PCP between 1995 and 1997 at 78 hospitals in seven metropolitan areas in the United States. The overall inpatient mortality rate was 11.3%. Hierarchically optimal classification tree analysis identified an ordered five-category staging system based on three predictors: wasting, alveolar-arterial oxygen gradient (AaPO(2)), and serum albumin level. The mortality rate increased with stage: 3.7% for Stage 1, 8.5% for Stage 2, 16.1% for Stage 3, 23.3% for Stage 4, and 49.1% for Stage 5. This new staging system may be useful for severity of illness adjustment in the current era while exploring current variation in HIV-associated PCP inpatient mortality rates among hospitals and across cities.