299 Predictive Performance of NELA Versus P-POSSUM Mortality Scores; Are We Underestimating the Risk of Mortality Following Emergency Laparotomy?

Abstract

Abstract Aim To compare the performance of NELA and P-POSSUM mortality risk scores in predicting 30-day and 90-day mortality in patients undergoing emergency laparotomy. Method A retrospective cohort study was conducted to compare predicative performance of pre-operative NELA, post-operative NELA and P-POSSUM predicted mortality scores in patients undergoing emergency laparotomy between 2014 and 2021. The outcomes of interest included the observed 30-day and 90-day mortality. The discrimination of the mortality tools was assessed and compared by determining the Area Under the Curve (AUC) for each tool using Receiver Operating Characteristic curve analysis. Results A total of 681 patients were included. The observed risk of 30-day and 90-day mortality were 10.4% (71/681) and 14.2% (97/681), respectively. In terms of 30-day mortality, the AUC was 0.791 (0.727-0.855) for pre-operative NELA score, 0.784 (0.721-0.848) for pre-operative P-POSSUM score, and 0.761 (0.699-0.824) for post-operative NELA score. In terms of 90-day mortality, the AUC was 0.765 (0.708-0.821) for pre-operative NELA score, 0.749 (0.692-0.807) for pre-operative P-POSSUM score, and 0.745 (0.691-0.800) for post-operative NELA score. Observed/Expected ratio for 30-day and 90-day mortality were calculated as 3.25 and 4.43 for pre-operative NELA, 2.81 and 3.84 for pre-operative P-POSSUM, and 2.17 and 2.96 for post-operative NELA, respectively. Pairwise comparisons showed no statistically significant difference in discrimination among the three models. Conclusions Pre-operative NELA, post-operative NELA and P- POSSUM scores underestimated the risk of 30-day and 90-day mortality for patients undergoing emergency laparotomy. No significant difference in predictive performance was found among the three models.