Sex differences in perioperative heart rate variability and recovery in gastric cancer patients undergoing robot-assisted gastrectomy: a retrospective cohort study using wearable monitoring

Purpose This study aims to analyze sex differences in perioperative autonomic dysfunction in gastric cancer (GC) patients using a wearable HRV monitoring device. Additionally, we explore the relationship between HRV, sex, and postoperative recovery. Methods A total of 160 GC patients were enrolled and divided into two sex-based groups, with 80 patients in each group. Perioperative HRV, inflammatory markers, and nutritional indices were monitored. Time to first flatus, postoperative length of stay (PLOS), and complications were compared between groups. Furthermore, the correlation between HRV indices and PLOS was analyzed. Results Perioperative HRV trajectories differed significantly between sexes (all sex × time interactions P < 0.001), with variable magnitude, direction and timing of across‑index sex‑related differences. Overall, females showed smaller postoperative declines and faster restoration toward preoperative HRV values. Female patients also showed lower postoperative inflammatory markers, higher cortisol (Cor) levels, shorter first flatus time. Both POD1 pNN50 and POD1 rMSSD were identified as independent predictors of prolonged PLOS. The Receiver Operating Characteristic (ROC) curve analysis revealed an apparent AUC of 0.864, and after bootstrap internal validation, the optimism-corrected AUC was 0.822, indicating good discriminative performance with expected shrinkage upon validation. Conclusion Female sex was associated with more favorable autonomic recovery (as reflected by faster HRV restoration) and lower postoperative systemic inflammatory markers, although postoperative cortisol levels were higher in females. These patterns may contribute to faster gastrointestinal recovery. POD1 pNN50 and POD1 rMSSD were identified as independent predictors of prolonged PLOS. HRV indices show promise as non-invasive biomarkers for monitoring perioperative recovery, though these exploratory findings require rigorous external validation in larger, multicenter prospective studies before any clinical application can be considered.