The role of functional status in predicting inpatient mortality with AIDS: a comparison with current predictors

Abstract

To assess the independent prognostic role of functional status, as reflected by a measure of an inpatient's global requirement for nursing assistance with basic activities of daily living (Global ADL), we compared Global ADL with three validated AIDS mortality predictors: the Clinical AIDS Prognostic Staging (CAPS); the Severity Classification System for AIDS Hospitalization--version 2 (SCAH-2); and CD4 cell count. Our study sample consisted of 1392 patients with AIDS and a hospital stay of 3 or more days at one of 20 hospitals in 11 U.S. cities with high AIDS incidence. Data were collected from September 1990 through December 1991. Two percent of patients refused participation, and 26% were eliminated due to incomplete data collection, leaving an analytic sample of 1003 patients. Only 30% of patients had a CD4 count measured at any time during hospitalization. Cox regression was used to measure the hazard of inpatient mortality adjusted for length of stay. Overall mortality was 12%. Mortality rates for patients in Global ADL stages I-IV were 3%, 8%, 19%, and 51%, respectively (p < 0.0001). Global ADL more effectively discriminated mortality than CAPS (p < 0.001), SCAH-2 (p < 0.001), or CD4 count (p < 0.001). Global ADL also added independent information in analyses adjusted for both CAPS and SCAH-2: a single stage increase of Global ADL demonstrated a 1.9-fold increased hazard of death (CI: 1.6, 2.3). SCAH-2, assigned at discharge, was not strongly correlated with admission predictors (Global ADL: r = 0.17; CI: 0.11, 0.23 or CAPS: r = 0.03, CI: 0.02, 0.17). We conclude that Global ADL, alone or in tandem with other severity systems, provides an excellent severity adjustment for inpatient mortality with AIDS. Finally, CD4 cell counts were not routinely available and were not as predictive as Global ADL in the patients for whom both were available.