Estimation of physiologic ability and surgical stress (E-PASS) for a surgical audit in elective digestive surgery

Background. This study was undertaken to establish. an equation to estimate mortality with the use of the prediction scoring system designated as the Estimation of Physiologic Ability and Surgical Stress (E-PASS), and to evaluate the system's usefulness in defining quality of care by comparing it with the Physiologic and Operative Severity Score for the enUmeration for Mortality and morbidity (POSSUM) and Portsmouth-possum (P-POSSUM) scoring systems previously generated for surgical audit. Methods. Patients (n = 5212; group A) who underwent elective gastrointestinal surgery were analyzed to establish equations for estimated 30-day and in-hospital mortality rates. The usefulness of E-PASS was evaluated in another series of 1934 patients (group B) who underwent elective digestive surgery in 6 national hospitals. The ratio of observed to estimated mortality rates (OE ratio) of each hospital was defined as a measure of quality. Results. In group A, 30-day and in-hospital mortality rates increased as the Comprehensive Risk Score (CRS) increased, providing equations for estimated mortality rates. There was an excellent correlation between the estimated and observed mortality rates in individual diseases: R = 0.958, N = 6, P = .0027 for in-hospital mortality; R = 0.937, N = 6, P = .0059 for 30-day mortality. In all patients of group B, the E-PASS system estimated the 30-day mortality rates by 0.63-fold (linear analysis), whereas the POSSUM score was 11. 0-fold (exponential analysis). The E-PASS system estimated the in-hospital mortality rates by 1.2-fold (linear analysis), whereas the P-POSSUM score was 4.5-fold (linear analysis). The OE ratios for 30-day mortality among the 6 hospitals defined by E-PASS correlated well with those defined by POSSUM: R = 0.996, N = 6, P < .0001. Similarly, the OE ratios for in-hospital mortality defined by E-PASS were also highly correlated with those defined by P-POSSUM: (R = 0.929, N = 6, P = .0075. Conclusions. The E-PASS scoring system may be useful in defining surgical quality and may be more accurate than existing systems in evaluating elective digestive surgery.