APACHE III outcome prediction after esophagectomy

Introduction

The Acute Physiology and Chronic Health Evaluation (APACHE) III prognostic system has not been validated in patients admitted to the ICU after esophagectomy.

Hypothesis

APACHE III predicts hospital mortality after esophagectomy.

Methods

A retrospective review of all adult patients admitted to a single thoracic ICU after esophagectomy between October 1994 and December 2003. Patient demographics, ICU admission day APACHE III score, actual and predicted hospital mortality and length of hospital and ICU stays were collected for the first ICU admission only. Performance of the APACHE III prognostic system was assessed by the Hosmer–Lemeshow statistic for calibration and the area under the receiver operating characteristic curve (AUC) for discrimination.

Results

There were 924 esophagectomies performed during the study period. Data are presented for the 483 patients that were admitted to the ICU. Mean age was 63.9 years. Mean APACHE III score on the day of ICU admission was 41.5 (standard deviation 18.1). Mean predicted (standard deviation) ICU and hospital mortality rates were 3.01% (6.31) and 7.90% (11.0), respectively. Median (interquartile range) lengths of ICU and hospital stay were 1.68 (0.79–3.79) and 13.52 (12.0–21.0) days, respectively. Observed ICU and hospital mortality rates were 2.7% (13 of 483 patients) and 5.4% (26 of 483), respectively.

There were differences (P < 0.001) between survivors to hospital discharge and non-survivors in age, acute physiology score and APACHE III score. Predicted ICU and hospital survival rates on the day of ICU admission were also different when survivors were compared with non-survivors (P < 0.001). Although most patients were male (82.6%), gender did not predict survival. The mean (95% confidence interval [CI]) ICU and hospital length of stay ratios (observed/predicted) were 0.88 (0.76–1.00) and 1.01 (0.92–1.10), respectively.

The standardized ICU and hospital mortality ratios (95% CI), based on APACHE III prediction, were 0.89 (0.41–1.38) and 0.68 (0.42–0.94), respectively. In predicting mortality, the AUC of APACHE III prediction was 0.860 (95% CI 0.791–0.928) and the Hosmer–Lemeshow statistic was 8.581 with a P value of 0.379.

Conclusions

The APACHE III prognostic scoring system has good discrimination and calibration in predicting hospital mortality of patients admitted to the ICU following esophagectomy. The low number of deaths may have influenced the statistical analyses.