Metabolic frailty measured by TyG-HFRS and atrial fibrillation in elderly GERD patients admitted to the ICU

The triglyceride-glucose index combined with the Hospital Frailty Risk Score (TyG-HFRS) reflects metabolic frailty and systemic vulnerability. Its association with atrial fibrillation (AF) in elderly patients with gastroesophageal reflux disease (GERD) remains unclear. A total of 489 elderly GERD patients from the MIMIC-IV database were analyzed. TyG-HFRS was computed as the product of TyG and HFRS and evaluated as a continuous variable (per-IQR), quartiles (Q1-Q4), and trend. Multivariable logistic regression models (Model 0–4) were constructed with progressive adjustments. Dose-response relationships were examined using restricted cubic spline (RCS). Predictive improvement was assessed using AUC, continuous net reclassification improvement (NRI), and integrated discrimination improvement (IDI). Subgroup analyses and exploratory mediation analyses (APSIII, LODS, SIRS) were performed. Higher IQR-scaled TyG-HFRS was independently associated with higher odds of AF (Model 4: aOR ≈ 1.74). Patients in Q4 had substantially higher odds of AF compared with Q1. RCS analysis showed a significant overall association (P-overall = 0.002) without detected departure from linearity (P-non-linear = 0.083). Adding TyG-HFRS per IQR to the base model modestly improved discrimination (AUC: 0.650→0.682), with NRI (0.47) and IDI (0.026). In component analyses, this improvement was driven principally by the frailty component (HFRS alone AUC 0.685; TyG alone was not independently associated with AF, aOR 0.92, p = 0.58). Subgroup analyses did not reveal statistically significant effect modification, although subgroup-specific confidence intervals were wide. Exploratory mediation analysis suggested that APSIII (18.2%), LODS (14.3%), and SIRS (6.7%) may partly account for the TyG-HFRS-AF association, though these estimates are exploratory. IQR-scaled TyG-HFRS is associated with AF in elderly GERD patients and improved discrimination over the base model, although this improvement was driven principally by the frailty component. TyG-HFRS may serve as a valuable metabolic frailty marker for AF stratification.