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.