Development and validation of a nomogram incorporating GSTO1 for predicting postoperative cognitive dysfunction after cardiac valve replacement: a prospective cohort study

Abstract Background Postoperative cognitive dysfunction (POCD) is a common complication after cardiac valve replacement, which impairs patients’ quality of life and increases long-term adverse outcomes; however, reliable predictive tools for POCD remain lacking. Objective The aim of this study was to develop and validate a nomogram incorporating the biomarker GSTO1 for predicting POCD after cardiac valve replacement. Methods A prospective cohort of 278 patients undergoing cardiac valve replacement was divided into training and validation sets (7:3 ratio). Serum GSTO1 levels were measured by ELISA before surgery and on postoperative day 2. Cognitive function was evaluated using the MMSE and MoCA at four time points (preoperative baseline, postoperative day 2, pre-discharge, and 42 days post-discharge). Univariate analysis identified potential predictors, and multivariate logistic regression determined independent risk factors. A nomogram was constructed and its performance assessed by the area under the ROC curve (AUC), calibration plots with Hosmer–Lemeshow tests, and decision curve analysis (DCA). Results In the training cohort ( n = 195), 34 patients (17.4%) developed POCD within 6 weeks postoperatively. Five independent predictors were identified: older age, presence of chronic comorbid diseases, low intraoperative BIS during CPB, longer CPB duration, and higher postoperative day 2 GSTO1 level. The nomogram integrating these factors achieved AUCs of 0.879 (training) and 0.868 (validation). Calibration curves showed good agreement between predicted and observed outcomes (Hosmer–Lemeshow P = 0.744 for training; P = 0.203 for validation). DCA demonstrated clinical utility, with a net benefit observed for probability thresholds of 4–86% (training) and 7–72% (validation). Conclusion Incorporating GSTO1 resulted in a nomogram with high accuracy, good calibration, and clinical utility for identifying patients at risk of POCD after cardiac valve replacement.