Efficacy of the APACHE II score at ICU discharge in predicting post-ICU mortality and ICU readmission in critically ill surgical patients

In this study, we evaluated the efficacy of the discharge Acute Physiology and Chronic Health Evaluation (APACHE) II score in predicting post-intensive care unit (ICU) mortality and ICU readmission during the same hospitalisation in a surgical ICU. Of 1190 patients who were admitted to the ICU and stayed >48 hours between October 2007 and March 2010, 23 (1.9%) died and 86 (7.2%) were readmitted after initial ICU discharge, with 26 (3.0%) admitted within 48 hours. The area under the receiver operating characteristics curve of the discharge and admission APACHE II scores in predicting in-hospital mortality was 0.631 (95% confidence interval [CI] 0.603 to 0.658) and 0.669 (95% CI 0.642 to 0.696), respectively (P=0.510). The area under the receiver operating characteristics curve of discharge and admission APACHE II scores for predicting all forms of readmission was 0.606 (95% CI 0.578 to 0.634) and 0.574 (95% CI 0.545 to 0.602), respectively (P=0.316). The area under the receiver operating characteristics curve of discharge APACHE II score in predicting early ICU readmissions was, however, higher than that of admission APACHE II score (0.688 [95% CI 0.660 to 0.714] versus 0.505 [95% CI 0.476 to 0.534], P=0.001). The discharge APACHE II score (odds ratio [OR] 1.1, 95% CI 1.01 to 1.22, P=0.024), unplanned ICU readmission (OR 20.0, 95% CI 7.6 to 53.1, P=0.001), eosinopenia at ICU discharge (OR 6.0, 95% CI 1.34 to 26.9, P=0.019), and hospital length-of-stay before ICU admission (OR 1.02, 95% CI 1.01 to 1.03, P=0.021) were significant independent factors in predicting post-ICU mortality. This study suggests that the discharge APACHE II score may be useful in predicting post-ICU mortality and is superior to the admission APACHE II score in predicting early ICU readmission in surgical ICU patients.