Impact of Vascular Access Type and Obesity on Long-Term Thrombosis and Access Failure in Hemodialysis: A Real-World Cohort Study from the TriNetX Global Collaborative Network

Background/Objectives: Optimal vascular access remains a critical determinant of outcomes in patients undergoing maintenance hemodialysis. While an arteriovenous fistula (AVF) is generally preferred over an arteriovenous graft (AVG), the impact of obesity and antithrombotic therapy on access-related complications remains incompletely defined. This study evaluated the association between vascular access type, obesity status, and adverse outcomes in a large real-world cohort. Methods: We conducted a retrospective cohort study using de-identified electronic health record data from the TriNetX Global Collaborative Network. Adult patients (≥18 years) receiving maintenance hemodialysis were stratified by vascular access type (AVF vs. AVG), body mass index (normal: 18.5–24.9 kg/m2, obese: ≥30 kg/m2), and antithrombotic medication exposure. Propensity score matching (1:1) was performed within BMI strata. Primary outcomes included vascular access thrombosis, AVG failure, and AVF failure. Time-to-event analyses used Kaplan–Meier and Cox proportional hazards models. Results: AVG was associated with significantly higher rates of thrombosis and access failure compared with AVF in both obese and normal-weight cohorts (all p < 0.0001). In patients with obesity, thrombosis rates increased from 10.47% (AVF) to 17.54% (AVG) at 3 months to 34.32% versus 42.24% at 5 years. Kaplan–Meier analysis demonstrated early and persistent separation of thrombosis-free survival curves, with AVG associated with increased risk (HR 1.23; 95% CI, 1.07–1.41; log-rank p = 0.0001). Antithrombotic therapy reduced absolute risks but did not eliminate the relative disadvantage of AVG. Conclusions: In this large real-world cohort, AVG was consistently associated with higher risks of thrombosis and access failure compared with AVF, regardless of obesity status or medication exposure. These findings support preferential use of AVF and highlight the need for individualized vascular access strategies in patients undergoing hemodialysis.