Preoperative Geriatric Nutritional Risk Index as a Novel Predictive Factor for Postoperative Delirium in Elderly Patients Following Total Hip Arthroplasty: A Retrospective Propensity-matched Study

Delirium is a common complication in elderly patients after total hip arthroplasty (THA). Malnutrition is common in the elderly and is closely associated with developing postoperative delirium (POD). Therefore, preoperative assessment of the patient's nutritional status is necessary. The geriatric nutritional risk index (GNRI) is a reliable indicator of nutritional status in the elderly population, but the relationship with postoperative delirium is not clear.The aim of this study was to determine the effect of preoperative GNRI on postoperative delirium.We reviewed 688 elderly patients who underwent primary elective THA at our medical center between 2013 and 2023. Delirium was diagnosed by reviewing postoperative medical records during hospitalization, using diagnostic criteria from the Diagnostic and Statistical Manual IV and the Confusion Assessment Method. Propensity matching was used to match patients in the delirium and non-delirium groups. Multiple logistic regression analysis was used to determine the association between GNRI and postoperative delirium. The validity of the GNRI for predicting POD was assessed by the area under the receiver operating characteristic curve (AUC) and the optimal prediction threshold was calculated.When matched, the GNRI was significantly higher for the delirium group than the non-delirium group (89.0 ± 8.0 vs. 99.8 ± 8.1, p < 0.001). In multivariate logistic regression analysis, GNRI was an independent risk factor for POD, and the incidence of POD increased with lower GNRI (OR 0.846, 95% CI 0.792-0.904, p < 0.001). The results of the ROC analysis showed an AUC of 0.827 and a prediction cut-off of 95.7 for the GNRI (sensitivity: 85.7%, specificity: 68.6%).In elderly patients, a lower GNRI was significantly associated with the occurrence of POD after THA. Assessing GNRI prior to THA in elderly patients may be effective in predicting the risk of POD.