Preoperative risk stratification for mortality and major morbidity in major colorectal surgery.

INTRODUCTION: Risk stratification in major colorectal surgery, in general, has used preoperative, intraoperative, and postoperative variables, and has been used for purposes of comparative audit. To enable preoperative clinical use, this study aimed to stratify risk by use of preoperative risk factors only.
METHODS: This is a single-institutional prospective observational study.
RESULTS: There were 887 major colorectal procedures assessed. Independent risk factors for mortality were American Society of Anesthesiologists' physical status Grades III to V, age, high comorbidity count, and low surgeon case volume. For major morbidity, risk factors were American Society of Anesthesiologists' Grades III to V, urgent operation, and operation to excise the rectum. Overall, mortality was 4.51%, and major morbidity was 19.6%. The estimated risk of mortality was stratified by risk factor profile from 0.12% (95% CI, 0.02-0.93) to 42.4% (95% CI, 23.5-63.9). The risk of major morbidity was stratified from 7.22% (95% CI, 4.82-10.7) to 49.2% (95% CI, 34.2-64.4). Model discrimination was favorable to the existing risk adjustment models applied to our cohort. The Physiological and Operative Severity Score for the enumeration of Mortality and Morbidity (including Portsmouth and ColoRectal modifications), and Association of ColoProctology of Great Britain and Ireland Colorectal Cancer models (mortality: area under receiver operating characteristic (AU ROC) curves 0.87 compare 0.70-0.81, major morbidity: 0.69 compare 0.66)).
CONCLUSIONS: Simple and readily available preoperative risk factors can achieve risk stratification. Risk stratification based on preoperative risk factors only possibly has comparable efficacy with those models that use preoperative, intraoperative, and postoperative risk factors.