Nutritional Risk Index: A Predictive Metric for Mortality After Lung Transplant

Abstract

Malnourishment is associated with poor outcomes after lung transplantation. Validated screening tools for patients awaiting lung transplants are needed. We assessed the association of the Nutritional Risk Index (NRI) with outcomes after lung transplantation. We categorized adult patients (aged more than 18 years) undergoing incident lung transplantation in the Scientific Registry of Transplant Recipients between 2005 and 2018 (n= 13,392) according to NRI categories of malnutrition: none, 100 or greater; mild, 97.5 to 100 or less; moderate, 83.5 to 97.5 or less; and severe, less than 83.5. We used Cox models to characterize the association of NRI categories with all-cause mortality within 5 years, graft failure within 1 year, and length of stay. In a subset of patients (n= 11,634), we used logistic regression to assess the association of NRI with airway dehiscence, reintubation, and chest tube placement. Of the 13,392 lung transplant recipients (mean age 55 years; 58.6% male) in the study, the most common indication for transplant was idiopathic pulmonary fibrosis (36.2%), followed by chronic obstructive pulmonary disease (27.3%), and cystic fibrosis (12.6%). Based on the NRI, 54.4% were non-malnourished, 12.4% mildly, 25.9% moderately, and 7.2% severely malnourished. Five-year mortality was higher among patients with severe malnutrition (44.6%) compared with patients who were non-malnourished (38.9%). Severe malnourishment remained significantly associated with higher mortality risk, with adjustment for covariates (hazard ratio 1.47; 95% confidence interval, 1.26 to 1.58). The length of stay was significantly longer among patients with severe malnutrition (median 15 days) compared with non-malnourished recipients (median 18 days). This difference persisted after adjustment for covariates (severe malnutrition hazard ratio 0.85; 95% confidence interval, 0.79 to 0.91). The NRI before transplant is an independent predictor of postoperative mortality and morbidity among lung transplant patients.