Modifications to the Geriatric Nutritional Risk Index Predicts Complications after Total Joint Arthroplasty.

Background: Preoperative malnutrition is a known risk factor for postoperative complications following total joint arthroplasty (TJA), however, there is scant literature comparing which nutritional index is best at predicting these outcomes. The purpose of this study was to investigate the utility of the Maastricht Index (MI), Onodera's Prognostic Index (OPNI), the Geriatric Nutritional Risk Index (GNRI), and a novel, modified Geriatric Nutritional Risk Index (mGNRI) in predicting periprosthetic joint infection (PJI), wound complications (WC), readmission, and reoperation rates after TJA.

Methods: A single-center, retrospective cohort study was performed of patients who underwent primary TJA from January 2016 to December 2021. The ninety-day preoperative albumin, prealbumin, and total lymphocyte count (TLC) were collected. Outcome measures were PJI, WC, readmission, and return to the operating room. Youden's Index (YI) and Receiver Operator Characteristic (ROC) curves were used to determine optimal cut-off points. Multivariable logistic regression was used to adjust for potential confounders, including body mass index (BMI), age, and the Charlson Comorbidity Index (CCI).

Results: There were 1,575 patients included in the study. The mGNRI had the greatest accuracy (area under the curve (AUC) = 0.633; optimal cut-off point = 92.8) in predicting postoperative adverse outcomes. Complication rates were significantly higher in the low mGNRI group (≤ 92.8). When controlled for BMI, CCI, and age, the odds of PJI, WC, readmission, and reoperation in patients who had low mGNRI were 6.61 (P = 0.005), 3.04 (P = 0.021), 2.25 (P = 0.020), and 2.75 (P = 0.024), respectively.

Conclusion: The mGNRI is an easy-to-calculate nutritional index and an excellent predictor of postoperative complications following TJA. The mGNRI outperformed GNRI, MI, and OPNI in predicting postoperative complications. Our results suggest that patients who fall below the mGNRI threshold of 92.8 should be carefully considered for nutritional optimization prior to total joint arthroplasty.