SO047IMPROVED SURVIVAL WITH CONVERSION FROM NON FUNCTIONAL TO FUNCTIONAL ARTERIOVENOUS FISTULA AFTER HEMODIALYSIS INITIATION - FINDINGS FROM THE FRENCH REIN REGISTRY

Abstract

Introduction and Aims: Starting hemodialysis with non-functional arteriovenous fistula (NF-AVF) is associated with higher mortality, but whether or not this is due to poor vascular access conversion after initiation is unknown. We therefore assessed mortality risk associated with NF-AVF at hemodialysis initiation, accounting for subsequent changes in vascular access, in patients from the French REIN Registry. Methods: We studied all patients aged ≥18 who started hemodialysis between 2005 and 2012 in France. Those who started with a catheter despite earlier AVF creation were considered as having NF-AVF. We compared vascular access conversion between patients with NF-AVF and those without AVF at baseline by the means of cumulative incident function and Gray's test considering death and renal transplantation as competing risks. Time-dependent Cox proportional hazard models, accounting for changes in vascular access, were used to assess mortality hazard ratios (HR) and 95% confidence intervals (95% CI) associated with NF-AVF compared with functional AVF (F-AVF) at hemodialysis initiation. Results: Of the 53 092 incident patients included, 47% had started hemodialysis with F-AVF, 9% with NF-AVF and 44% without AVF. The median follow-up was 3 years (range 1-9 years). Cumulative incidence of F-AVF after hemodialysis initiation showed higher rates of conversion in patients with NF-AVF than in those without AVF at baseline (57% versus 36% at 1 year of follow-up, 62% versus 41% at 2 years and 64% versus 43% at 3 years, Grays's test p value <0.0001). Mortality HR associated with NF-AVF at initiation depended on conversion to F-AVF during follow-up. Compared with patients with F-AVF from baseline (67 221 person-years), those with NF-AVF who subsequently converted to F-AVF (7 716 person-years) had a mortality HR of 1.08 (95% CI 1.00-1.15) before and 0.95 (95% CI 0.89-1.03) after adjustment for gender, age, primary renal disease, diabetes, cardiovascular comorbidities, malignancy, mobility impairment, body mass index, serum albumin, anemia status, estimated GFR at initiation, type of dialysis facility and dialysis start condition (planned or unplanned). In patients with NF-AVF, but who did not convert to F-AVF (4 467 persons-years), mortality HRs were 1.62 (95% CI 1.51-1.74) before and 1.43 (95% CI 1.31-1.55) after adjustment. Conclusions: Among patients starting hemodialysis with NF-AVF, a significant proportion will never experience sucessful conversion to F-AVF, which may explain the mortality excess risk in this group. This study shows that patients who converted to F-AVF after initiation achieved similar survival as those with F-AVF from dialysis start. Further efforts in AVF creation before and after hemodialysis onset may improve patients' outcomes.