Should current criteria for detecting and repairing arteriovenous fistula stenosis be reconsidered? Interim analysis of a randomized controlled trial.

BACKGROUND The vascular access guidelines recommend that arteriovenous fistulas (AVFs) with access dysfunction and an access blood flow (Qa) <300-500 mL/min be referred for stenosis imaging and treatment. Significant (>50%) stenosis, however, may be detected in a well-functioning AVF with a Qa > 500 mL/min, too, but whether it is worth correcting or not remains to be seen. METHODS In October 2006, we began an open randomized controlled trial enrolling patients with an AVF with subclinical stenosis and Qa > 500 mL/min, to see how elective stenosis repair [treatment group (TX)] influenced access failure (thrombosis or impending thrombosis requiring access revision), or loss and the related cost compared with stenosis correction according to the guidelines, i.e. after the onset of access dysfunction or a Qa < 400 mL/min [control group (C)]. An interim analysis was performed in July 2012, by which time the trial had enrolled 58 patients (30 C and 28 TX). RESULTS TX led to a relative risk of 0.47 [95% confidence interval (CI): 0.17-1.15] for access failure (P = 0.090), 0.37 [95% CI: 0.12-0.97] for thrombosis (P = 0.033) and 0.36 [95% CI: 0.09-0.99] for access loss (P = 0.041). In the setting of our study (in which all surgery was performed as in patient procedure) no significant differences in costs emerged between the two strategies. The mean incremental cost-effectiveness ratio for TX was €282 or €321 to avoid one episode of thrombosis or access loss, respectively. CONCLUSIONS Our interim analysis showed that elective repair of subclinical stenosis in AVFs with Qa > 500 mL/min cost-effectively reduces the risk of thrombosis and access loss in comparison with the approach of the Kidney Disease Outcomes Quality Initiative (KDOQI) guidelines, raising the question of whether the currently recommended criteria for assessing and treating stenosis should be reconsidered.