Association Between the Prognostic Nutritional Index and Outcomes in Patients Undergoing Emergency Laparotomy

Background: Nutritional status is a key determinant of surgical outcomes, but its assessment in emergency settings remains challenging. The prognostic nutritional index (PNI), which is derived from the serum ALB concentration and lymphocyte count, is a rapid, objective measure of nutritional and immune status. This study evaluated the associations between the PNI and postoperative outcomes in patients undergoing emergency laparotomy. Methods: A retrospective observational study was conducted at a single district general hospital in England, including adult patients who underwent emergency laparotomy between January 2019 and December 2023. The PNI was calculated as PNI = serum albumin (g/L) + 0.005 × total lymphocyte count (cells/μL). Patients were classified as malnourished (PNI < 50) or not malnourished (PNI ≥ 50). The outcomes assessed included postoperative complications, length of hospital stay (LOS), 30-day readmission, and three-year all-cause mortality. Statistical analyses included chi-square, Mann–Whitney U, logistic regression, and Kaplan–Meier survival analyses. Results: Among 482 patients (median age 68 years; 57% male), 66% were malnourished. Malnutrition was significantly associated with higher ASA grade (p < 0.001), frailty (p = 0.028), and comorbidity burden (p < 0.001). Malnourished patients had longer LOSs (≥12 days, p < 0.001) and higher 30-day readmissions (p = 0.026). Multivariate analysis revealed that comorbidities, stoma formation, and prolonged LOS were independent predictors of a low PNI. Kaplan–Meier analysis revealed reduced three-year survival in malnourished patients (log-rank p < 0.01). Conclusion: Malnutrition, as defined by a low PNI, is highly prevalent and associated with adverse postoperative outcomes in emergency laparotomy. PNI is a simple, objective, and clinically useful tool that should be incorporated into preoperative assessments to guide early nutritional optimization.