Simplified Acute Physiology Score II for measuring severity of illness in intermediate care units

Objectives To assess the efficacy of the Simplified Acute Physiology Score (SAPS II) in intermediate care units. A number of patients hospitalized in the intensive care unit (ICU) could be hospitalized in alternative structures, intermediate care units, which are equipped to handle their monitoring needs and able to provide adequate treatment at a lower cost. Characterization of the patients relies on the assessment of their severity of illness by severity scores. The efficiency of severity scores has been established in ICU patients, but not in the setting of intermediate care units. Design Prospective study. Setting Intermediate care unit of a multidisciplinary hospital. Patients Four hundred thirty-three patients admitted to the intermediate care unit. Interventions None. Measurements and Main Results Of 561 consecutive patients admitted to the intermediate care unit during a 12-mo period, 433 patients could be included in the analysis. Patients were admitted from the emergency ward (60.9%). Of the study patients, 60.9% were admitted from the emergency ward for mostly (96%) medical reasons. Average length of stay was 3.1 +/- 2.3 (SD) days. Death rate in the intermediate care unit was 2.7% (n = 11). Average SAPS II was 22.3 +/- 12.0 (range 6 to 73). Hospital death rate was 8.1%, whereas the expected mortality rate derived from SAPS II was 8.7%. To assess the performance of the system, a formal goodness-of-fit test was performed to evaluate calibration. Calibration was accurate using the C coefficient of Hosmer-Lemeshow statistics (C = 2.4; p > 0.5). The discriminant power of SAPS II, measured by the area under the receiver operating characteristic curve was excellent (0.85 +/- 0.04). Conclusions The SAPS II assessment of severity of illness in patients admitted to an intermediate care unit is reliable. These results will need to be confirmed, using different patient samplings from intermediate care units. (Crit Care Med 1998; 26:1368-1371)