Modification of POSSUM Score for Gastrointestinal Surgery

Tsuneo Tanaka, Yasuhiro Matsugu, Tatsuro Ishimoto, Naoki Kagawa, Hideki Nakahara, Yasuhiko Fukuda and Junko Tanaka*

Department of Surgery, Hiroshima Prefectural Hospital
Department of Biomedical Sciences, Hiroshima University Graduate School*

Background: The Physiological and Operative Severity Score for the enUmeration of Mortality and morbidity (POSSUM) has been found to overestimate the mortality rate or the incidence of postoperative complications, Therefore, many modifications have been reported. We modified the formula used by POSSUM to estimate the operative risk based on our data for gastrointestinal surgery and evaluated whether or not this modified POSSUM system would allow a more accurate risk assessment. Materials & Methods: The subjects of this study were 1573 patients who underwent gastrointestinal surgery in our department during the four-year period from January 2002 to December 2005. A multivariate analysis was then conducted using data obtained during the first half of this period (n=709). An equation for calculating the predictive mortality rate was obtained from this analysis and was named the "Hiroshima POSSUM (H-POSSUM)". Three kinds of POSSUM were prospectively obtained during the latter half of the above-mentioned period (n=864). The accuracy of estimation was analyzed using the O/E ratio (observed cases/expected cases). We selected six kinds of operations, and estimated the accuracy of POSSUM using the O/E ratio. Results: The O/E ratio for the morbidity rate was 0.78 using the original POSSUM and 1.04 using the H-POSSUM. The O/E ratio for mortality rate was 0.12 using the original POSSUM, 0.56 using the Portsmouth POSSUM, and 0.94 using the H-POSSUM. The O/E ratios obtained using the H-POSSUM were nearest to 1.00. The accuracy of the H-POSSUM was superior to the original and the P-POSSUM in simulation of six groups. Conclusion: Our modified version of POSSUM was useful for assessing the risks of gastrointestinal surgery.

Key words
gastrointestinal surgery, POSSUM, risk analysis

Reprint requests
Tsuneo Tanaka Department of Surgery, Hiroshima Prefectural Hospital
1-5-54 Ujinakanda, Minami-ku, Hiroshima, 734-8530 JAPAN

Accepted
July 26, 2006

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