Comparison of P-POSSUM and Cr-POSSUM scores in patients undergoing colorectal cancer resection.

Objectives: To compare the Portsmouth (P) Physiological and Operative Severity Score for the Enumeration of Mortality and Morbidity (POSSUM) and specialized colorectal (Cr) POSSUM scoring systems in the prediction of mortality after resection of colorectal cancer.

Design: Retrospective study of patients after resection of colorectal cancer.

Setting: University hospital.

Patients: One hundred twenty patients with complete medical records who underwent resection of colorectal cancer between January 1, 1996, and December 31, 2004, at our institution were enrolled in the study.

Main Outcome Measures: P-POSSUM and Cr-POSSUM scores were calculated for each patient. In-hospital mortality rate and number of deaths within 30 days after surgery were recorded. The ratio of observed to expected deaths was calculated for each analysis.

Results: The P-POSSUM system underpredicted mortality by 25%, with no significant difference between the predicted and observed values (P = .96). The observed to expected ratio for Cr-POSSUM was 1.11, with no significant difference between the observed and predicted values (P = .19). Area under the receiver operating curve for P-POSSUM was 0.70 and for Cr-POSSUM was 0.59.

Conclusions: Both P-POSSUM and Cr-POSSUM perform well in predicting mortality after colorectal cancer surgery, but the Cr-POSSUM is more accurate. There is a constant need for reevaluation of existing and any new scoring systems outside original development and validation populations. The Cr-POSSUM score is a promising specialized tool for monitoring surgical outcomes in colorectal cancer surgery.