The prognostic nutritional index on postoperative day one is associated with one-year mortality after burn surgery in elderly patients

Abstract

Background: Burn injury in elderly patients can result in poor outcomes. Prognostic nutritional index (PNI) can predict the perioperative nutritional status and postoperative outcomes. We aim to evaluate the risk factors, including PNI, for one-year mortality after burn surgery in elderly patients. Methods: Burn patients aged ≥65 years were retrospectively included. PNI was calculated using the following equation: 10 × serum albumin level (g/dL) + 0.005 × total lymphocyte count (per mm3). Cox regression, receiver operating characteristic curve and Kaplan-Meier survival analyses were performed to evaluate the risk factors for postoperative one-year mortality. Results: Postoperative one-year mortality occurred in 71 (37.6%) of the 189 elderly burn patients. Risk factors for one-year mortality were PNI on postoperative day one (hazard ratio (HR) = 0.872; 95% CI = 0.812-0.936; p < 0.001), Sequential Organ Failure Assessment score (HR = 1.112; 95% CI = 1.005-1.230; p = 0.040), American Society of Anesthesiologists physical status (HR = 2.064; 95% CI = 1.211-3.517; p = 0.008), total body surface area burned (HR = 1.017; 95% CI = 1.003-1.032; p = 0.015) and preoperative serum creatinine level (HR = 1.386; 95% CI = 1.058-1.816; p = 0.018). The area under the curve of PNI for predicting one-year mortality after burn surgery was 0.774 (optimal cut-off value = 25.5). Patients with PNI ≤25.5 had a significantly lower one-year survival rate than those with PNI >25.5 (32.1% vs 75.9%, p < 0.001). Conclusions: PNI on postoperative day one was associated with postoperative one-year mortality in elderly burn patients. The postoperative one-year survival rate was lower in patients with PNI ≤25.5 than in those with PNI >25.5. These findings indicate the importance of identifying elderly burn patients with low PNI, thereby reducing the mortality after burn surgery.