Usefulness of nutritional assessment using Geriatric Nutritional Risk Index as an independent predictor of 30-day mortality after hip fracture surgery

Abstract

Introduction: The Geriatric Nutritional Risk Index (GNRI) is an objective nutritional status assessment tool used for predicting mortality risk in hospitalized patients. However, it is unclear whether GNRI reflects short-term mortality for hip fracture patients after surgery. We examined the usefulness of the nutritional status assessed by the GNRI and identified cutoff scores that predict mortality risk. Does GNRI on admission predict the mortality after surgery for hip fracture?

Hypothesis: Evaluation of GNRI could help identify patients at higher risk of 30-day mortality after hip fracture surgery.

Materials and methods: This retrospective study used data from 1040 patients who underwent hip fracture surgery. Fatalities within 30 days after hip fracture surgery were investigated. The GNRI was calculated on admission in all patients as follows: 14.89×serum albumin (g/dL)+41.7×body mass index/22. Receiver operating characteristic (ROC) curves were used to calculate the area under the curve (AUC) and the optimal cutoff score that could predict 30-day mortality after hip fracture surgery. This cutoff score was used for comparing the mortality rates between patient groups with a GNRI higher and lower than the cutoff score using Fisher's exact test. Logistic regression analysis was used to determine risk factors of 30-day mortality.

Results: There were 17 fatalities (1.6%) in the cohort. The ROC-AUC value was 0.811, and the cutoff GNRI was 75.4. Mortality was significantly higher in the group with a GNRI<75.4 compared with the group with a GNRI≥75.4 (odds ratio [OR], 22.99; 95% confidence interval [95% CI], 7.55-78.05; p=0.00000004). A GNRI<75.4 was a significant predictor of mortality within 30-days after hip fracture surgery (OR, 27.1; 95% CI, 8.57-85.9; p≤0.0001).

Discussion: Our results show that nutritional status assessment using GNRI can help predict 30-day mortality among geriatric patients undergoing surgery for hip fracture. The GNRI is a simple and accurate tool for predicting the risk of mortality after hip fracture surgery.

Level of evidence: IV; case series study.

Keywords: Geriatric Nutritional Risk Index; Hip fracture; Mortality; Nutrition.