Prognostic value of the Geriatric Nutritional Risk Index in patients undergoing cardiac surgery: a systematic review and meta-analysis

Background The Geriatric Nutritional Risk Index (GNRI) is a key indicator of nutritional status in elderly individuals. Poor nutritional status has been linked to unfavorable surgical outcomes, but its prognostic value in cardiac procedures remains uncertain. This meta-analysis investigates the relationship between the GNRI and prognosis in cardiac surgery patients. Methods A comprehensive literature search was performed across the PubMed, Embase, and Web of Science databases. Studies were included if they evaluated preoperative GNRI and reported short-term mortality, long-term mortality, or major postoperative complications, such as acute kidney injury (AKI), wound complications, and infections. Risk ratios (RRs) and 95% confidence intervals (CIs) were calculated to compare outcomes between patients with low and normal GNRI. Heterogeneity was assessed using the I 2 statistic, and a random-effects model was used to synthesize and analyze the results from the included studies. Results The pooled results of 16 cohort studies involving 7,593 patients showed that a low preoperative GNRI was significantly associated with an increased risk of short-term mortality (RR: 3.19, 95% CI: 1.68–6.07, p 0.001; I 2 = 39%) and long-term mortality (RR: 2.32, 95% CI: 1.63–3.30, p 0.001; I 2 = 77%). Low GNRI was correlated with a higher risk of AKI (RR: 1.77, 95% CI: 1.11–2.81, p = 0.02; I 2 = 74%) and overall infection (RR: 3.35, 95% CI: 2.01–5.57, p 0.001; I 2 = 29%), while no significant association was observed for wound complications, although this outcome was based on only four studies. Meta-regression identified mean age as a significant contributor to heterogeneity in long-term mortality ( p = 0.04), while sample size explained part of the heterogeneity in short-term mortality (adjusted R 2 = 23.5%). Conclusion A low preoperative GNRI is correlated with an increased risk of mortality and postoperative complications in cardiac surgery patients. Preoperative nutritional assessment using GNRI may identify high-risk patients. Systematic review registration PROSPERO ID CRD42025637322.