The Nutritional Risk Index as a Predictor of 90-Day Dialysis Dependence After Acute Renal Failure: A Pilot Study

Objective: Return of sufficient renal function to discontinue dialysis following acute renal failure is an important clinical and patient-oriented outcome. Our study sought to develop a model using the Nutritional Risk Index (NRI) to predict 90-day dialysis dependence.

Methods: We retrospectively analyzed 77 patients with acute renal failure admitted to a single university medical center's intensive care units between January 2015 and January 2019 with the need for continuous renal replacement therapy. We assessed the predictive ability of the NRI for 90-day dialysis dependence using age, serum total protein, number of vasopressor days, baseline predialysis estimated glomerular filtration rate (eGFR), and Sequential Organ Failure Assessment (SOFA) score as covariates.

Results: Of the analytic group, 20 (25.9%) had severe nutritional risk, and 16 (20.8%) recovered from acute renal failure at 90 days. The mean age was 57.1 years. The clinical model comprising the NRI, age, serum total protein, number of vasopressor days, SOFA score, and baseline predialysis eGFR had an area under the curve (AUC) of 0.89 (95% confidence interval [CI], 0.81-0.97), sensitivity 56.3%, and specificity 95%. Exclusion of baseline predialysis eGFR and SOFA score did not significantly decrease model discrimination, AUC 0.87 (95% CI, 0.78-0.97). The AUC was least when serum total protein was dropped from the final model, 0.79 (95% CI, 0.66-0.92).

Conclusions: The NRI when used together with other clinical parameters, including serum total protein, may improve the accuracy of predicting renal recovery and independence from dialysis at 90 days.