Comparison of POSSUM scoring systems and the surgical risk scale in patients undergoing surgery for complicated diverticular disease

PURPOSE: This study was designed to evaluate the accuracy of the Physiologic and Operative Severity Score for the enUmeration of Mortality and morbidity, Portsmouth-Physiologic and Operative Severity Score for the enUmeration of Mortality and morbidity, colorectal-Physiologic and Operative Severity Score for the enUmeration of Mortality and morbidity, and the Surgical Risk Scale for the treatment of patients with complicated diverticular disease. METHODS: Physiologic and Operative Severity Score for the enUmeration of Mortality and morbidity variables were prospectively recorded for 324 patients undergoing colorectal resections in 42 hospitals in the United Kingdom from January to December 2003. The accuracy of each model was evaluated by measures of discrimination, calibration, and subgroup analysis. RESULTS: The overall operative mortality was 10.8 percent (Physiologic and Operative Severity Score for the enUmeration of Mortality and morbidity-estimated mortality rate, 21.9 percent; Portsmouth-Physiologic and Operative Severity Score for the enUmeration of Mortality and morbidity-estimated mortality rate, 10.5 percent; colorectal-Physiologic and Operative Severity Score for the enUmeration of Mortality and morbidity-estimated mortality rate, 10 percent; Surgical Risk Scale-estimated mortality rate, 38.2 percent). Physiologic and Operative Severity Score for the enUmeration of Mortality and morbidity and the Surgical Risk Scale over-predicted mortality in young patients (P < 0.001) and Portsmouth-Physiologic and Operative Severity Score for the enUmeration of Mortality and morbidity underpredicted mortality in elderly patients (P < 0.001). Physiologic and Operative Severity Score for the enUmeration of Mortality and morbidity and the Surgical Risk Scale overpredicted mortality in patients with generalized peritonitis (Hinchey III and IV). There was no significant difference between the observed and colorectal-Physiologic and Operative Severity Score for the enUmeration of Mortality and morbidity predicted mortality across patient subgroups and when the overall sample was considered. CONCLUSIONS: The study suggested a lack of calibration of Physiologic and Operative Severity Score for the enUmeration of Mortality and morbidity, Portsmouth-Physiologic and Operative Severity Score for the enUmeration of Mortality and morbidity, and the Surgical Risk Scale at the extreme of age and for patients with severe peritoneal contamination. Colorectal-Physiologic and Operative Severity Score for the enUmeration of Mortality and morbidity was found to accurately evaluate mortality arising from complicated diverticular disease.