Predicting Mortality of Patients With Sepsis: A Comparison of APACHE II and APACHE III Scoring Systems

BACKGROUND: Acute Physiology, Age and Chronic Health Evaluation (APACHE) II and III scores were developed in 1985 and 1991, respectively, and are used mainly for critically ill patients of all disease categories admitted to the intensive care unit (ICU). They differ in how chronic health status is assessed, in the number of physiologic variables included (12 vs. 17), and in the total score. These two scoring systems have not been compared in predicting hospital mortality in patients with sepsis. METHODS: We retrospectively identified all septic patients admitted to our 54-bed medical-surgical ICU between June 2009 and February 2014 using the APACHE outcomes database. We calculated correlation coefficients for APACHE II and APACHE III scores in predicting hospital mortality. Receiver-operating characteristic (ROC) curves were also used to assess the mortality predictions. RESULTS: We identified a total of 2,054 septic patients. Average APACHE II score was 19 ± 7, and average APACHE III score was 68 ± 28. ICU mortality was 11.8% and hospital mortality was 18.3%. Both APACHE II (r = 0.41) and APACHE III scores (r = 0.44) had good correlations with hospital mortality. There was no statistically significant difference between the two correlations (P = 0.1). ROC area under the curve (AUC) was 0.80 (95% confidence interval (CI): 0.78 - 0.82) for APACHE II, and 0.83 (95% CI: 0.81 - 0.85) for APACHE III, suggesting that both scores have very good discriminative powers for predicting hospital mortality. CONCLUSIONS: This study shows that both APACHE II and APACHE III scores in septic patients were very strong predictors of hospital mortality. APACHE II was as good as APACHE III in predicting hospital mortality in septic patients.