Usefulness of the preoperative prognostic nutritional index score as a predictor of the outcomes of lung transplantation: A single-institution experience

Abstract

There is increasing evidence that preoperative nutritional status is a predictor of disease severity and mortality after lung transplantation (LTX). This study aimed to evaluate preoperative nutritional assessment as a predictor of LTX outcomes. We included 132 patients who underwent single or double LTX at Severance Hospital, Yonsei University, between October 2010 and April 2016. The Prognostic Nutritional Index (PNI) scores were calculated as follows: 10 × serum albumin value (g/dL)+0.005 × peripheral lymphocyte count (/mm3). The optimal cut-off PNI score for the prediction of postoperative overall survival was set at 41.15 using receiver operating characteristics analysis. The efficacies of PNI and other clinical factors in predicting LTX outcomes were determined using univariate and multivariate Cox proportional hazard analyses. Patients with PNI <41.15 (PNI-low group) were older, had higher preoperative C-reactive protein levels, and had lower nutritional status scores than did those in the PNI-high group (PNI≥41.15). Based on Kaplan-Meier analysis, the overall survival rate was significantly better in the PNI-high group (78.3%) than in the PNI-low group (28.6%) (P<0.001). Age, sex, body mass index, use of preoperative mechanical ventilation, C-reactive protein level, neutrophil-to-lymphocyte ratio, and PNI score were independent prognostic factors. Survival was significantly higher in the PNI-high group (hazard ratio: 0.220; P<0.001) than in the PNI-low group, and incidence of complications≥grade IV was higher in the PNI-low group than in the PNI-high group (P<0.001). Multivariate regression analysis showed that preoperative PNI score was significantly associated with postoperative survival, even after adjusting for other confounding factors. Our findings suggest that PNI is a useful prognostic marker for the identification of high-risk lung transplant recipients. Preoperative nutritional assessment using PNI may provide useful information for reducing postoperative morbidity and mortality.