Abstract 172: Cumulative SAPS II Score Fails to Predict Mortality in Out-of-Hospital Cardiac Arrest
Introduction: Severity of illness scores can predict outcomes in critically ill patients. However, the calibration of existing scoring systems in post-cardiac arrest patients is poorly established.
Objective: To determine if the Simplified Acute Physiology Score (SAPS II) will predict mortality in out-of-hospital cardiac arrest (OHCA).
Methods: An observational study of adult cardiac arrest at an urban tertiary care hospital during the period from 12/2007 to 12/2010. Data were collected prospectively and recorded in the Utstein style. Inclusion criteria: 1. Adult (>18 years); 2. OHCA; 3. Return of spontaneous circulation. Traumatic cardiac arrests were excluded. Patient demographics, co-morbid conditions, vital signs and laboratory data and in-hospital mortality were recorded. SAPS II scores were calculated. We used simple descriptive statistics to describe the study population and logistic regression to predict mortality with SAPS II as the predictor variable. Forward stepwise logistic regression selection was used to identify individual SAPS II variables that contribute to the sensitivity of the score. Discrimination was assessed using area under the curve (AUC) of the receiver operating characteristic (ROC) curve.
Results: 115 patients were analyzed. The median age was 68 years (IQR: 55 - 79) and 28% were female. Median SAPS II score was 67 (IQR: 53 - 77) and 61% of patients died. Cumulative SAPS II score was a poor predictor of mortality (p = 0.19, OR: 1.012, 95% CI: 0.99 - 1.03) and demonstrated poor discrimination (AUC: 0.61). Stepwise selection identified the following individual SAPS II variables to predict mortality: HC03 (p = 0.006, OR: 1.46, 95%CI: 1.12 - 1.90), GCS (p = 0.03, OR: 1.12, 95%CI: 1.01 - 1.23), and age (p = 0.02, OR: 1.12, 95%CI: 1.02 - 1.23); together these are strong predictors of mortality: p = 0.02, AUC: 0.75.
Conclusion: Cumulative SAPS II scoring fails to predict mortality in OHCA. The risk-score assigned to age, GCS and HC03 independently predict mortality and combined are good mortality predictors. These findings suggest that an alternative severity of illness score should be used in post-cardiac arrest patients. Future studies should determine optimal risk-scores of SAPS II variables in a larger cohort of OHCA.
- © 2011 by American Heart Association, Inc.