A Comprehensive Meta-Analytical Review Comparing the Mannheim Peritonitis Index (MPI) and POSSUM Scoring Systems in Predicting Outcomes of Secondary Peritonitis

Background Secondary perforation peritonitis represents one of the most formidable and frequently Secondary perforation peritonitis is a serious and common surgical emergency worldwide, marked by severe illness, high rates of complications, and significant risk of death. high morbidity, and significant mortality. Even though source control, critical care resuscitation, and targeted antimicrobial therapy have all improved, death rates are still very different, ranging from 10% to over 30% depending on the patient’s physiological reserves and the cause of the perforation. For surgical planning, patient counselling, and institutional auditing, it is important to have accurate and repeatable risk stratification. This meta-analytical review assesses, contrasts, and integrates the predictive accuracy of the disease-specific Mannheim Peritonitis Index (MPI) with the physiology-based POSSUM (Physiological and Operative Severity Score for the Enumeration of Mortality and Morbidity) scoring systems. Methods A systematic review and meta-analysis of 40 original articles comparing MPI and POSSUM (including its Portsmouth modification, p-POSSUM, and the colorectal variant, CR-POSSUM) in patients undergoing emergency laparotomy for secondary perforation peritonitis was conducted in accordance with PRISMA guidelines. We gathered and organized data on sensitivity, specificity, observed-to-expected (O/E) mortality ratios, and the Area Under the Receiver Operating Characteristic Curve (AUC) for both mortality and morbidity. The results showed that both scoring systems were excellent at predicting postoperative outcomes. The combined analysis showed that POSSUM and p-POSSUM were better at predicting death overall (mean AUC 0.88 to 0.94) than the MPI (mean AUC 0.75 to 0.89). POSSUM also showed an unmatched ability to predict postoperative morbidity, which is something that MPI doesn’t do as well. Classic POSSUM, on the other hand, always tended to overestimate death rates in the highest-risk groups (O/E ratio < 1). The p-POSSUM equation fixed this problem for the most part. On the other hand, the MPI showed great specificity (85% to 97%) and was easy to calculate during surgery, making it a very useful tool in emergency situations. Conclusions POSSUM and p-POSSUM are statistically better at predicting overall surgical morbidity and mortality, but their complicated math makes them less useful at the bedside in places where resources are limited. The MPI is still a very specific and easy-to-use tool, and hospitals should consider using a mix of methods that use the Mannheim Peritonitis Index (MPI) for making immediate surgical decisions and the p-POSSUM for reviewing and improving surgical quality later on. Real-time surgical decision-making and the p-POSSUM are used for retrospective quality assurance and surgical auditing.