Performance of Critical Care Outcome Prediction Models in an Intermediate Care Unit.

BACKGROUND: Intermediate care units (IMCUs) are heterogeneous in design and operation, which makes comparative effectiveness studies challenging. A generalizable outcome prediction model could improve such comparisons. However, little is known about the performance of critical care outcome prediction models in the intermediate care setting. The purpose of this study is to evaluate the performance of the Acute Physiology and Chronic Health Evaluation version II (APACHE II), Simplified Acute Physiology Score version II (SAPS II) and version 3 (SAPS 3), and Mortality Probability Model version III (MPM0III) in patients admitted to a well-characterized IMCU. MATERIALS AND METHODS: In the IMCU of an academic medical center (July to December 2012), the discrimination and calibration of each outcome prediction model were evaluated using the area under the receiver-operating characteristic and Hosmer-Lemeshow goodness-of-fit test, respectively. Standardized mortality ratios (SMRs) were also calculated. RESULTS: The cohort included data from 628 unique IMCU admissions with an inpatient mortality rate of 8.3%. All models exhibited good discrimination, but only the SAPS II and MPM0III were well calibrated. While the APACHE II and SAPS 3 both markedly overestimated mortality, the SMR for the SAPS II and MPM0III were 0.91 and 0.91, respectively. CONCLUSIONS: The SAPS II and MPM0III exhibited good discrimination and calibration, with slight overestimation of mortality. Each model should be further evaluated in multicenter studies of patients in the intermediate care setting.

Hospital mortality prediction for intermediate care patients: Assessing the generalizability of the Intermediate Care Unit Severity Score (IMCUSS).

PURPOSE: The Intermediate Care Unit Severity Score (IMCUSS) is an easy to calculate predictor of in-hospital death, and the only such tool developed for patients in the intermediate care setting. We sought to examine its external validity. MATERIALS AND METHODS: Using data from patients admitted to the intermediate care unit (IMCU) of an urban academic medical center from July to December of 2012, model discrimination and calibration for predicting in-hospital death were assessed using the area under the receiver operating characteristic (AUROC) and the Hosmer-Lemeshow goodness-of-fit chi-squared (HL GOF X2) test, respectively. The standardized mortality ratio (SMR) with 95% confidence intervals (95% CI) was also calculated. RESULTS: The cohort included data from 628 unique admissions to the IMCU. Overall hospital mortality was 8.3%. The median IMCUSS was 10 (Interquartile Range: 0-16), with 229 (36%) patients having a score of zero. The AUROC for the IMCUSS was 0.72 (95% CI: 0.64-0.78), the HL GOF X2 = 30.7 (P < 0.001), and the SMR was 1.22 (95% CI: 0.91-1.60). CONCLUSIONS: The IMCUSS exhibited acceptable discrimination, poor calibration, and underestimated mortality. Other centers should assess the performance of the IMCUSS before adopting its use.