A rapid preadmission method for predicting inpatient course of disease for patients with HIV-related Pneumocystis carinii pneumonia

Pneumocystis carinii pneumonia (PCP) has been the most common reason for hospitalization and the most common cause of death for persons with HIV infection. Hospital mortality rates for PCP range from 10 to 60%. Studies that evaluate differences in hospital mortality rates must control for differences in patient severity of illness. We developed a simple staging system for categorizing severity of illness in patients with PCP. We analyzed the relation between clinical factors and in-hospital mortality for 576 hospitalized patients with HIV-related PCP treated at 56 hospitals for the years 1987 to 1990. Four stages of PCP could be identified based on three routinely measured clinical variables: alveolar-arterial oxygen difference, total lymphocyte count, and body mass index. The mortality rate increased by stage: 1% for Stage 1, 8% for Stage 2, 23% for Stage 3, and 48% for Stage 4. The four-stage severity system compared well with previous models developed for AIDS and for PCP, and is easier to use in clinical practice. Our staging system identifies patients with a high and low risk of in-hospital death upon admission. Physicians may benefit from consideration of PCP stage in deciding on management strategies. In addition, researchers involved in clinical trials of new agents for PCP might consider stratification by PCP stage in order to define homogenous groups.