Access Type-Specific Vascular Access Creation Timing in Incident Hemodialysis: A Nationwide Cohort Study

INTRODUCTION: The lead time needed for vascular access (VA) creation before hemodialysis (HD) initiation remains unclear. Because arteriovenous fistulas (AVFs) and arteriovenous grafts (AVGs) differ in expected time to cannulation, the association between VA timing and outcomes may differ by access type. METHODS: Using the Korean National Health Insurance Service database, we identified incident HD patients in 2013 who underwent AVF or AVG creation before HD initiation. Patients were classified according to the interval from VA creation to HD initiation: VA0 (<1 month), VA1 (1 to <3 months), VA3 (3 to <6 months), VA6 (6 to <9 months, reference), VA9 (9 to <12 months), and VA12 (12 to ≤24 months). Catheter use, patency loss, and mortality were analyzed separately in AVF and AVG patients using logistic regression, Kaplan-Meier analysis, and Cox models. RESULTS: Among 24,713 patients, 20,894 underwent AVF and 3,819 underwent AVG creation. In AVF patients, compared with VA6, VA0 and VA1 were associated with higher catheter use (odds ratios, 14.03 and 1.85), primary patency loss (hazard ratios [HRs], 2.64 and 1.16), secondary patency loss (HRs, 4.56 and 1.12), and mortality (HRs, 1.67 and 1.25). In AVG patients, adverse associations were mainly observed in VA0, including higher catheter use (odds ratio, 8.45), primary patency loss (HR, 1.97), secondary patency loss (HR, 2.06), and mortality (HR, 1.43). Primary patency loss was also higher in VA1. CONCLUSION: The association between VA creation timing and outcomes differed between AVF and AVG. For AVF, creation at least 3 months before HD initiation was associated with more favorable outcomes. For AVG, adverse associations for most outcomes were concentrated within 1 month before HD initiation.