Impact of arteriovenous fistula formation on trajectory of kidney function decline: a target trial emulation

ABSTRACT Background Prior nonrandomized studies have suggested nephroprotective effects of arteriovenous fistula (AVF) formation, but these are plausibly susceptible to immortal time and selection biases. Methods We studied patients attending nephrology clinics in the West of Scotland during 2010–22 with an estimated glomerular filtration rate (eGFR) ≤15 mL/min/1.73 m2 and no prior AVF. Using target trial emulation and a sequential trial design, we simulated a hypothetical trial that would randomize patients to either undergo AVF formation immediately or not to undergo AVF formation. The primary outcome was the difference in eGFR slope for the first 6 months of follow-up, estimated using a mixed-effects model. The secondary outcomes were 5-year absolute risks of dialysis and death, estimated using the Aalen–Johansen and Kaplan–Meier estimators respectively. Results A total of 1364 unique patients (mean age 51.1 years, 55.7% male) contributed 3125 person-trials, with 561 in the AVF and 2564 in the no AVF group. Mean eGFR was 12.6 mL/min/1.73 m2 and the median number of eGFR measurements per person-trial was 7 (interquartile range 4–12). Slope of eGFR decline did not differ significantly between the AVF and no AVF groups (between-group difference –0.67 mL/min/1.73 m2/year, 95% CI –1.43, 0.10). The 5-year absolute risk of dialysis was 87% (95% CI 84, 91) in the AVF group and 75% (95% CI 73, 77) in the no AVF group, and the 5-year survival probability was 77% (95% CI 70, 83) in the AVF group and 67% (95% CI 64, 69) in the no AVF group. Conclusions In this study of patients with advanced chronic kidney disease, there was no evidence of a nephroprotective effect of AVF formation.