Comparison of preoperative Nutritional Risk Index and Body Mass Index for predicting immediate postoperative outcomes following major gastrointestinal surgery: Cohort-study

BACKGROUND: Malnutrition is a major risk factor for morbidity and mortality following gastrointestinal (GI) surgery. Nutritional Risk Index (NRI) and Body Mass Index (BMI) are the two well-validated tools that are readily available and do not add financial burden to the patients. The study aimed to analyze NRI and BMI as a preoperative nutritional indicator of postoperative complications following GI surgeries. METHODS: It is an observational study, where preoperative nutritional status and early postoperative complications <30 days (infectious or noninfectious) were studied. The patients admitted between July 2015 to May 2017, who underwent major GI surgeries were included in the study. The correlation between NRI and BMI of these patients were evaluated. RESULTS: The rate of wound infection was 4 (30.7%) out of 13 in severe malnutrition subgroup defined by NRI <83.5 which was found to be statistically significant (p = 0.003). However, it was not significant in a subgroup of patients with undernutrition defined by BMI <18.49%. In a subgroup analysis, abnormal NRI was found to be statistically significant (p = 0.004) in patients with malignant disease and malnutrition 64 (47.76%) out of 97 (72.3%). The mean NRI (94.49 ± 9.164) better correlated with advancing age (p < 0.05) and the correlation coefficient of 0.3100 showed a significant negative correlation. With 10 fold increase in age (r(2) = 0.096) the likelihood of malnutrition was 9.6% and subsequently increased postoperative complications. CONCLUSION: In cases of malignancy and advanced age, NRI is a better predictor of immediate postoperative outcome than BMI.