Role of nutritional indices (PNI, CONUT, GNRI) in predicting delirium in hospitalised individuals: A systematic review and meta-analysis.

BACKGROUND

Malnutrition is a known but often underestimated as a risk factor for delirium in hospitalised patients. This systematic review and meta-analysis aims to assess the predictive value of the Prognostic Nutritional Index (PNI), Controlling Nutritional Status (CONUT) score, and Geriatric Nutritional Risk Index (GNRI) for occurrence of delirium.

METHODS

A comprehensive literature search was performed on PubMed, Embase, Scopus, and Web of Science databases from inception to October 10, 2025. Observational studies assessing the association between PNI, CONUT, or GNRI and delirium were included. Random-effects meta-analyses were performed to pool odds ratios (ORs) with 95% confidence intervals (CIs). Subgroup, sensitivity, and meta-regression analyses were used to explore heterogeneity, and publication bias was evaluated using funnel plots and Egger's test.

RESULTS

Twenty-five studies comprising more than 45,000 participants were included. Lower PNI was strongly correlated with higher odds of delirium (categorical: OR = 1.57, 95% CI: 1.32-1.87; continuous: OR = 1.08, 95% CI: 1.04-1.12). Low GNRI also predicted delirium (OR = 1.58, 95% CI: 1.28-1.94), as did higher CONUT scores (OR = 2.99, 95% CI: 1.90-4.69). Subgroup analyses confirmed consistent associations across countries, study designs, and diagnostic methods. Meta-regression displayed no significant influence of age, sex, delirium prevalence, or cut-off thresholds. Publication bias was noted for PNI.

CONCLUSIONS

Poor nutritional status, as reflected by lower PNI and GNRI or higher CONUT scores, may independently predict the risk of delirium in hospitalised individuals. These indicators can act as simple and objective tools for assessing delirium risk.