Anticoagulant Use and Frequency of Vascular Access Thrombosis: A Retrospective Cohort Study

BACKGROUND: Hemodialysis (HD) patients with arteriovenous fistula (AVF) or arteriovenous graft (AVG) are often prescribed anticoagulation to prevent thrombosis, though evidence supporting this practice is limited. This study aimed to compare AVF and AVG thrombosis rates in HD patients with and without anticoagulation to inform clinical practice. METHODS: The authors conducted a retrospective analysis within Kaiser Permanente Northern California, an integrated health care system serving 4.6 million members. Patients initiating HD between January 1, 2013, and December 31, 2021, were identified and categorized based on anticoagulation use after dialysis initiation. Thrombosis rates of AVF and AVG were assessed within 1 year. RESULTS: A total of 9079 HD patients were included; 1837 received anticoagulation for various indications, 7242 did not. Compared to non-users, the anticoagulation cohort was older, had higher Charlson comorbidity scores, greater prevalence of hypertension and peripheral vascular disease, and lower aspirin use. After 1 year, AVF thrombosis rates were similar between groups. However, AVG thrombosis and bleeding events were more frequent among anticoagulated patients. No substantial differences in thrombosis or bleeding outcomes were observed between warfarin and apixaban users. CONCLUSION: Anticoagulation in HD patients did not reduce AVF or AVG thrombosis and was associated with increased bleeding risk. These findings may reflect differences in baseline patient characteristics. Randomized prospective studies are needed to clarify the role of anticoagulation in maintaining vascular access patency.