OBJECTIVE  To systematically evaluate the association between the geriatric nutritional risk index （GNRI） and the risk of postoperative infection in patients undergoing joint replacement surgery, to analyze its predictive value for postoperative infection in these patients, and to provide evidences for perioperative infection prevention and control.

METHODS  Searches were conducted in databases such as PubMed, Embase, Web of Science, Scopus, CNKI and CBMdisc to collect cohort studies on preoperative GNRI and postoperative infection in patients undergoing joint replacement surgery. The search covered all records from the establishment of the databases to Jul. 1, 2025. After screening the literature, extracting data, and assessing the risk of bias of the included studies through the Newcastle-Ottawa Scale （NOS）, a meta-analysis was conducted with RevMan 5.4 software and Stata 18.0 software.

RESULTS  A total of 10 studies involving 231 392 patients were included. Low GNRI was significantly associated with an increased risk of postoperative infection in joint replacement patients （RR=1.984, 95%CI: 1.598−2.462, P＜0.001）. Subgroup analysis indicated that the association between low GNRI and postoperative infection risk was independent of surgery types （primary/revision）, follow-up durations, surgical sites and study center types. The incidence of malnutrition was the main source of heterogeneity （P=0.028, R²=38.24%）. In the group with a high incidence of malnutrition, the association and consistency between low GNRI and postoperative infection risk were stronger than in the group with a low incidence of malnutrition （RR=4.094, I²=0% vs. RR=1.807, I²=82%）. Analysis by infection site indicated: low GNRI significantly increased the risk of pulmonary infection （RR=2.126, 95%CI: 1.838−2.458, P＜0.001）, surgical site infection （RR=1.763, 95%CI: 1.376−2.259, P＜0.001）, urinary tract infection （RR=1.689, 95%CI: 1.298−2.199, P＜0.001）, bloodstream infection （RR=2.120, 95%CI: 1.830−2.454, P＜0.001） and Clostridium difficile infection （RR=2.669, 95%CI: 1.450−4.758, P＜0.001）.

CONCLUSIONS  Low preoperative GNRI in patients undergoing joint replacement surgery is significantly associated with an increased risk of postoperative infection, and this association is even more pronounced in populations with a high incidence of malnutrition. Preoperative nutritional assessment with GNRI can identify patients at high risk of infection.