Evaluation of General ICU Outcome Prediction Using Different Scoring Systems
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- Category: Vol. 77, March 2009
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Evaluation of General ICU Outcome Prediction Using Different Scoring Systems,ABDULLAH HAMZA, LAMIAA HAMMED, MAGED ABULMAGD and AYMAN ELNAJAR
Abstract
Objective: The aim of this study was to evaluate the performance of three general severity-of-illness scores (Acute Physiology and Chronic Health Evaluation [APACHE] IV, Simplified Acute Physiology Score [SAPS] II, Mortality Probability Model [MPM] II0 systems) in Critical Care De-partment at Cairo University, Cairo, Egypt.
Methods: A prospective observational cohort study was performed in an Egyptian intensive care unit. Data were collected over the first 24 hours of ICU stay. The following data were collected prospectively on all consecutive patients admitted to the Intensive Care Unit between 20 January and 20 March 2008: Demographics, APACHE IV and SAPS II scores, MPM II0 variables, ICU outcome.
Measurements: Predicted mortality was calculated using original regression formulas. Standardized mortality ratio (SMR) was calculated with 95% confidence intervals (CI). Calibration was assessed by calculating Lemeshow-Hosmer goodness-of-fit C statistics. Discrimination was evaluated by calculating the Area Under the Receiver Operating Character-istic Curves (ROC AUC).
Results: A total of 265 consecutive patients were included over 3-month period. The observed ICU mortality was 17%. Predicted mortality by APACHE IV and SAPS II systems was different from actual mortality, whereas MPM II has the most accurate prediction one [SMR for APACHE IV: 1.49, SAPS II: 0.58, MPM II 0: 1.01]. All the models showed reasonable discrimination using the area under the receiver operating characteristic curve (APACHE IV, 0.845; SAPS II, 0.845; MPMII0, 0.81). For same data sets, APACHE IV demonstrated superior calibration to all the models using the chi-squared value from the Hosmer-Lemeshow test (APACHE IV 5.123 [p=0.744]; SAPS II 12.140 [p=0.145] and MPMII 8.825 [p=0.357].
Conclusions: In our ICU population: 1) Overall mortality prediction, estimated by standardized mortality ratio, was excellent for MPM, overestimated by SAPII and underesti-mated by APACHE IV. 2) APACHE IV and SAPS II demon-strated the best discrimination, but the superior calibration of
Correspondence to: Dr. Abdullah Hamza, Department of Critical Care, Faculty of Medicine, Cairo University, Cairo, Egypt.
APACHE IV makes it the most appropriate model for com-parisons of mortality rates in different ICUs.