NELA, P-POSSUM, and Paraspinal Muscle Index in risk stratification of elderly patients undergoing emergency laparotomy

BACKGROUND: Emergency laparotomy in older adults is associated with substantial morbidity and mortality, necessitating accurate and rapid preoperative risk stratification. Established risk models such as National Emergency Laparotomy Audit (NELA) and the Portsmouth Physiological and Operative Severity Score for the enUmeration of Mortality and Morbidity (P-POSSUM) are widely used, while computed tomography (CT)-derived sarcopenia indices have emerged as potential adjunctive markers of physiological vulnerability. However, the comparative performance of clinical risk scores and paraspinal muscle-based morphometric indices in elderly emergency surgery remains uncertain. The aim of this study was to evaluate the comparative performance of CT-derived morphometric indices, established risk models (NELA and P-POSSUM), and the Prognostic Nutritional Index (PNI) in predicting postoperative morbidity and in-hospital mortality in elderly patients undergoing emergency laparotomy. METHODS: This prospective, single-center cohort study included patients aged ≥65 years who underwent emergency laparotomy for acute abdomen between 2022 and 2023. Preoperative risk assessment included the NELA, P-POSSUM, and PNI scores. CT-derived sarcopenia was assessed using the Paraspinal Muscle Index (PSMI) and Fat-to-Muscle Ratio (FMR), measured on contrast-enhanced abdominal CT at the L3 level. Postoperative complications were graded according to the Clavien-Dindo classification. Correlation analyses and receiver operating characteristic (ROC) curve analyses were performed to evaluate associations with postoperative morbidity and in-hospital mortality. RESULTS: A total of 113 patients were included (mean age 74.1 ± 8.1 years; 61.1% male). Major postoperative complications (Clavien-Dindo ≥ 3) and in-hospital mortality were strongly associated with nutritional status. Lower PNI values were significantly associated with major complications, life-threatening complications (Clavien-Dindo ≥ 4), and in-hospital mortality. A PNI cut-off value of approximately 34.5 demonstrated moderate discriminative performance (Area under the curve (AUC) 0.760-0.768), with an AUC of 0.761 (95% CI 0.659-0.851) for mortality prediction. In contrast, PSMI and FMR showed no significant association with postoperative complication severity (PSMI: p = 0.479; FMR: p = 0.614) or mortality and did not correlate with clinical risk scores (all p > 0.05). As expected, NELA and P-POSSUM were significantly associated with postoperative outcomes (all p<0.001). However, the addition of PNI did not significantly improve model discrimination (NELA vs. NELA+PNI: ΔAUC=0.001, p=0.77; P-POSSUM vs. P-POSSUM+PNI: ΔAUC=0.032, p=0.17). CONCLUSIONS: In elderly patients undergoing emergency laparotomy, established clinical risk scores and nutritional status were strongly associated with postoperative outcomes, whereas CT-derived paraspinal muscle quantity indices did not reflect perioperative risk or complication severity. Future predictive models should integrate nutritional indices, muscle quality measures, functional frailty, and acute physiological parameters to improve risk stratification in elderly emergency surgery.