Association between the geriatric nutritional risk index and postoperative delirium: a meta-analysis

Background Malnutrition has been suggested as an important contributor to postoperative delirium (POD). The geriatric nutritional risk index (GNRI), a simple indicator based on serum albumin and body weight, has been increasingly evaluated in surgical patients. This meta-analysis aimed to clarify the association between GNRI and the risk of POD. Methods PubMed, Embase, and Web of Science were searched for observational studies evaluating the association between categorized GNRI and POD. Pooled risk ratios (RRs) and 95% confidence intervals (CIs) were calculated using random-effects models accounting for heterogeneity. Results Twelve cohort studies involving 12,332 surgical patients were included. Overall, low GNRI was associated with a significantly increased risk of POD (RR = 1.62, 95% CI: 1.34–1.96; I² = 27%). Subgroup analyses showed a stronger association in studies with mean patient age > 74 years compared to ≤ 74 years ( p for subgroup difference = 0.02) and in those using GNRI cutoffs < 98 compared to ≥ 98 ( p = 0.04). The association was weaker in studies using multivariate analyses compared with univariate analyses ( p = 0.01). Meta-regression indicated that GNRI cutoff values significantly influenced the pooled effect ( p = 0.04). The funnel plot showed mild asymmetry, whereas Egger’s test was not significant ( p = 0.11), and trim-and-fill analysis produced a similar pooled estimate (RR = 1.54, 95% CI: 1.26–1.87). Conclusions Low GNRI is associated with an increased risk of POD in surgical patients, suggesting that preoperative nutritional assessment may help identify individuals at higher risk for this complication. Systematic Review Registration The study protocol was registered prospectively in the PROSPERO database (registration number: CRD420261335609).