Modified POSSUM to predict postoperative morbidity following gastrectomy

Area of Science:

• Geriatric Surgery
• Surgical Oncology
• Clinical Risk Prediction

Background:

• Gastric cancer surgery in elderly patients presents unique challenges.
• Accurate prediction of postoperative morbidity is crucial for optimizing patient care.
• The Physiological and Operative Severity Score for the Enumeration of Mortality and Morbidity (POSSUM) is a widely used scoring system.

Purpose of the Study:

• To evaluate the accuracy of the POSSUM scoring system in predicting morbidity after gastrectomy for gastric cancer in patients aged 75 years and above.
• To develop and validate a modified POSSUM equation for improved morbidity prediction in this specific elderly patient cohort.

Main Methods:

• Retrospective analysis of 123 patients aged 75+ who underwent gastrectomy for gastric cancer (1994-2002).
• Calculation of POSSUM scores and comparison with observed postoperative morbidity and mortality rates.
• Development of a modified POSSUM equation based on retrospective data and prospective validation in 26 patients.

Main Results:

• The original POSSUM predicted a mortality rate of 47.9% and morbidity of 14.1%, while observed rates were 1.6% and 39.8% respectively.
• A modified POSSUM equation was derived: ln[R/(1-R)] = -2.59 + (0.087 x PS) + (0.013 x OS).
• Prospective validation showed the modified equation predicted morbidity at 37.3%, closely matching the observed 38.5%.

Conclusions:

• The standard POSSUM system significantly overestimates morbidity in elderly patients undergoing gastrectomy for gastric cancer.
• A modified POSSUM equation, developed from retrospective data, provides a more accurate prediction of postoperative morbidity in this population.
• This refined predictive tool can aid in clinical decision-making and patient management for elderly gastric cancer patients.