Validity of nutrition risk index as a malnutrition screening tool compared with subjective global assessment in end-stage renal disease patients on peritoneal dialysis

Abstract

We undertook this study to compare subjective global assessment (SGA) and nutrition risk index (NRI) as malnutrition screening tools in peritoneal dialysis (PD) patients. Nutrition status of the patients was categorized into low, moderate and high risk of malnutrition based on both NRI and SGA. The sensitivity, specificity and predictive values of NRI were compared with SGA, an already validated tool of nutrition status assessment in PD patients. Two hundred and eighty-three end-stage renal disease patients (age 50.02 ± 13.76 years; 204 males, 150 diabetic) were included. Based on SGA, 71/283 (25.08%) had normal nutrition, 192/283 (67.84%) mild–moderate and 20/283 (7.07%) severe malnutrition. Based on NRI, 38/283 (13.43%) patients had normal nutritional status, 193/283 (68.20%) mild-moderate and 52/283 (18.37%) severe malnutrition. Twenty-three of 283 (8.1%) were correctly classified as normal by NRI (true negative) and 197/283 (69.6%) as malnourished (true positive), 15/283 (5.3%) as false negative, 48/283 (16.96%) were misclassified as malnourished (false positive). NRI has sensitivity of 92.9% and specificity of 32.39%. Positive predictive value and Negative predictive values (NPVs) of NRI are 80.41% and 60.53%, respectively. Accuracy of the test is 78%. The receiver operating characteristic curve of NRI is 0.63. To conclude, NRI carries high sensitivity but low specificity as compared to SGA. It can be used as screening tool but not as a diagnostic tool for assessment of nutritional status in PD patients because of its low specificity and NPV.