Estimation of Mortality and Morbidity Risk in Colorectal Surgery using POSSUM Predictor Equation

Makoto Watanabe, Naokuni Yasuda, Tomokazu Kusano, Osamu Nakashima, Koji Kamisaka, Akira Tsunoda* and Mitsuo Kusano*

Department of Surgery, Isesaki Municipal Hospital
Department of Gastroenterological Surgery, Showa University School of Medicine*

Background: The physiological and operative severity score for enumeration of mortality and morbidity (POSSUM) is a simple scoring system validated in general surgical patients enabling estimation of the risk of postoperative complication and death. The Portsmouth predictor equation (P-POSSUM) is a modification that may more accurately predict death than POSSUM. We evaluated the validity of POSSUM and P-POSSUM in patients undergoing colorectal surgery in Japan. Patients and Methods: Physiological and operative severity scores in 119 patients undergoing elective and emergency colorectal surgery were recorded retrospectively. Observed morbidity and mortality were compared with the prediction by POSSUM or P-POSSUM using linear analysis. Results: The Hosmer-Lemeshow goodness of fit test indicated that the POSSUM morbidity equation had a significant lack of fit with observed complications (χ²=18.57, P=0.017). The POSSUM mortality equation overestimated deaths with this analysis (χ²=20.85, P=0.003) but the mortality rate estimated by P-POSSUM did not differ significantly from the observed death rate (χ²=1.92, P=0.38). Conclusion: Our results suggest that the POSSUM scoring system for morbidity risk must be modified, and the P-POSSUM scoring system for mortality risk is useful for patients undergoing colorectal surgery.

Key words
POSSUM, P-POSSUM, mortality, morbidity risk, colorectal surgery

Reprint requests
Makoto Watanabe Department of Surgery, Kawasaki Saiwai Hospital
39-1 Miyakomachi, Saiwai-ku, Kawasaki, 212-0021 JAPAN

Accepted
May 25, 2004

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