Acute Physiology and Chronic Health Evaluation (APACHE) III outcome prediction after major vascular surgery.

OBJECTIVE To investigate the performance of the Acute Physiology and Chronic Health Evaluation (APACHE) III scoring system in patients admitted to the intensive care unit (ICU) after major vascular surgery. DESIGN Retrospective cohort study. SETTING A tertiary referral center. PARTICIPANTS Three thousand one hundred forty-eight patients who underwent major vascular surgery between October 1994 and March 2006. INTERVENTIONS None. MEASUREMENTS AND MAIN RESULTS Data were abstracted from an institutional APACHE III database. Standardized mortality ratios (SMRs) (with 95% confidence intervals) were calculated. The area under the receiver operating characteristic curve (AUC) and Hosmer-Lemeshow C statistic were used to assess discrimination and calibration, respectively. The mean age of 3,148 patients studied was 70.5 years (+/- standard deviation 9.6). The mean Acute Physiology Score and the APACHE III score on the day of ICU admission were 31.0 (+/- 17.5) and 45.1 (+/- 18.8), respectively. The mean predicted ICU and hospital mortality rates were 3.2% (+/- 7.8%) and 5.0% (+/- 9.5%), respectively. The median (and interquartile range) ICU and hospital lengths of stay were 4.3 (3.6-5.1) and 14 days (11.9-16.8 days), respectively. The observed ICU mortality rate was 2.4% (75/3, 148 patients) and hospital mortality rate was 3.7% (116/3,148). The ICU and hospital SMRs were 0.74 (0.58-0.91) and 0.74 (0.61-0.88), respectively. The AUC of APACHE III-derived prediction of hospital mortality was 0.840 (95% confidence interval, 0.799-0.880), indicating excellent discrimination. The Hosmer-Lemeshow C statistic was 28.492, with a p value <0.01, indicating poor calibration. CONCLUSIONS The APACHE III scoring system discriminates well between survivors and nonsurvivors after major vascular surgery, but calibration of the model is poor.