The impact of frailty and sarcopenia index on postoperative nausea and vomiting in elderly patients undergoing sedation-assisted gastrointestinal endoscopy

BACKGROUND: Frailty and sarcopenia are age-related syndromes characterized by diminished physiological reserve and are associated with adverse health outcomes. This study aimed to investigate the combined impact of frailty and sarcopenia on postoperative nausea and vomiting (PONV) in elderly patients undergoing gastrointestinal endoscopy with sedation. METHODS: This prospective cohort study enrolled 703 patients aged ≥ 60 years who underwent sedation-assisted gastrointestinal endoscopy at Cangzhou Hospital of Integrated Traditional Chinese and Western Medicine from June 2025 to December 2025. Frailty was assessed using the Fried Frailty Phenotype, and sarcopenia was evaluated using the sarcopenia index (SI). The primary outcome was the incidence of PONV. Multivariable logistic regression, considering reflux esophagitis, motion sickness history, and intraoperative hypotension, was performed, and ROC curve analyses were performed to evaluate the associations of frailty and SI with PONV. RESULTS: The overall incidence of PONV was 31.6%. Multivariable logistic regression showed that frail patients had a significantly increased risk of PONV (OR = 3.237, 95%CI 2.287-4.594, P < 0.001). Similarly, lower SI levels were independently associated with an increased risk of PONV (OR = 0.887, 95%CI 0.799-0.982, P = 0.022). ROC curve analysis showed that frailty predicted PONV with an AUC of 0.642 (sensitivity 51.8%, specificity 76.5%), whereas SI alone showed limited discriminative ability (AUC 0.559). However, when frailty and SI were added to the base model (which included reflux esophagitis, motion sickness history, and intraoperative hypotension), the model's predictive performance significantly improved: the AUC increased from 0.587 to 0.664 (DeLong test P < 0.001), with a NRI of 0.563 (95%CI 0.404-0.721) and an IDI of 0.072 (95%CI 0.040-0.117). Employing the SI cutoff value of 6.442, we categorized patients into four groups. Using the non-frailty + high SI group as a reference, the risk of PONV increased progressively in the non-frailty + low SI group (OR = 1.760, 95%CI 1.077-2.843), frailty + high SI group (OR = 2.888, 95%CI 1.922-4.350), and frailty + low SI group (OR = 6.916, 95%CI 3.856-12.717). Interaction analysis showed a significant additive interaction between frailty and low SI on PONV. CONCLUSIONS: Frailty and low SI in elderly patients are significantly associated with an increased risk of PONV following gastrointestinal endoscopy with sedation. Although SI alone has modest discriminative ability, combining it with frailty enhances risk stratification. These findings indicate that assessing physiological reserve using the Fried phenotype and SI may improve preoperative risk evaluation and guide individualized antiemetic prophylaxis in older patients undergoing sedation-assisted endoscopy.