Operative mortality rates among surgeons: comparison of POSSUM and p-POSSUM scoring systems in gastrointestinal surgery.

PURPOSE

The original Physiological and Operative Severity Score for the enUmeration of Mortality and morbidity and the more recent Portsmouth predictor equation for mortality scoring systems were developed to provide risk-adjusted mortality rates in general surgery. The aim of this study was to compare crude and risk-adjusted operative mortality rates among four surgeons using the above scoring systems and assess their applicability for patients scored retrospectively.

METHODS

A total of 505 consecutive patients undergoing major gastrointestinal surgery were analyzed; 65 percent underwent colorectal, 27.5 percent underwent upper gastrointestinal, and 7.5 percent underwent small-bowel surgery. The observed:predicted mortality ratios using the Physiological and Operative Severity Score for the enUmeration of Mortality and morbidity and Portsmouth predictor equation for mortality scoring systems were calculated for each surgeon.

RESULTS

The actual overall operative mortality rate was 11.1 percent (elective was 3.9 percent, and emergency was 25.1 percent). The Portsmouth predictor equation for mortality equation predicted a mortality rate of 11.3 percent (P = 0.51). However, the Physiological and Operative Severity Score for the enUmeration of Mortality and morbidity scoring system was found to overpredict death by a factor of two: 21.5 percent (P < 0.001). Mortality rates among the four surgeons varied from 7.6 to 14.7 percent but depended on the proportion of elective vs. emergency surgery. The observed:predicted ratio for Portsmouth predictor equation for mortality was close to unity (0.905-1.067) for all surgeons, but it was 0.45 to 0.56 for Physiological and Operative Severity Score for the enUmeration of Mortality and morbidity.

CONCLUSION

The Portsmouth predictor equation for mortality equation seems to be a more accurate predictor of mortality in gastrointestinal surgery. It would seem to provide the best choice for analyzing operative mortality rates for individual surgeons, taking into account variation in case mix and fitness of patients even when scored retrospectively. This has important implications for the future assessment of surgeons' clinical standards and the assessment of quality of surgical care.