Predictors of Initiation for Predialysis Arteriovenous Fistula

Abstract

Background and objectives: The optimal timing of predialysis arteriovenous fistula surgery remains uncertain. We evaluated factors associated with hemodialysis initiation in patients undergoing predialysis arteriovenous fistula surgery and derived a model to predict future initiation of dialysis.

Design, setting, participants, & measurements: Our study retrospectively identified 308 patients undergoing predialysis arteriovenous fistula creation at a large medical center in 2006-2012 to determine whether they initiated hemodialysis. Multiple variable logistic regression analyzed which demographic and clinical factors predicted initiation of dialysis within 2 years of arteriovenous fistula surgery. A receiver operating characteristic area under the curve was used to quantify the predictive value of preoperative factors on the likelihood of initiating hemodialysis within 2 years.

Results: Overall, hemodialysis was initiated within 6 months, 1 year, and 2 years in 119 (39%), 175 (57%), and 211 (68%) patients, respectively. Using multiple variable logistic regression, four factors were associated with hemodialysis initiation at 2 years: eGFR at access surgery (odds ratio, 0.45; 95% confidence interval, 0.31 to 0.64 per 5 ml/min per 1.73 m2; P<0.001), diabetes (odds ratio, 2.51; 95% confidence interval, 1.22 to 5.15; P=0.003), GFR trajectory (odds ratio, 1.54; 95% confidence interval, 1.09 to 2.17 per 3 ml/min per 1.73 m2 per year; P=0.01), and spot urine protein-to-creatinine ratio (odds ratio, 1.39; 95% confidence interval, 1.14 to 1.71 per 1 U; P<0.001). eGFR alone had a moderate predictive value for dialysis initiation (area under the curve =0.69; 95% confidence interval, 0.63 to 0.76; P<0.001), whereas the full model had a higher predictive value (area under the curve =0.83; 95% confidence interval, 0.77 to 0.88; P<0.001).

Conclusions: The likelihood of initiating hemodialysis within 2 years of predialysis arteriovenous fistula surgery is associated with eGFR at access surgery, diabetes, GFR trajectory, and magnitude of proteinuria. The combined use of all four variables improves the ability to predict future hemodialysis compared with the use of eGFR alone.

Keywords: Area Under Curve; Humans; Logistic Models; Probability; ROC Curve; arteriovenous access; arteriovenous fistula; creatinine; diabetes mellitus; glomerular filtration rate; proteinuria; renal dialysis.

Copyright © 2016 by the American Society of Nephrology.

Figures

Figure 1.

Predialysis arteriovenous fistula (AVF) placement and time to hemodialysis initiation by eGFR at AVF placement. Hemodialysis initiation was more likely if the predialysis AVF was placed at lower eGFR. Bar graphs show the likelihood of initiating hemodialysis by eGFR at AVF placement (P<0.001 between eGFR groups at 6 months, 1 year, and 2 years).

Figure 2.

A faster eGFR trajectory, diabetes, and proteinuria are each associated with a higher likelihood of hemodialysis initiation within 2 years of arteriovenous fistulas (AVF) creation. Likelihood of initiation of dialysis at 2 years in patients with different eGFR values at arteriovenous fistula surgery stratified by (A) eGFR trajectory (Traj; ≥5 versus <5 ml/min per 1.73 m2 in the preceding year), (B) diabetes, and (C) magnitude of proteinuria (urine protein-to-creatinine ratio ≥2 versus <2; both urine protein and urine creatinine were expressed as milligrams per deciliter). DM, diabetes mellitus; HD, hemodialysis.

Figure 3.

Receiver operating characteristic (ROC) curves to evaluate the predictive value of baseline clinical factors at arteriovenous fistula surgery on the likelihood of initiating hemodialysis within 2 years. For eGFR alone, area under the curve (AUC) was 0.69 (95% confidence interval [95% CI], 0.63 to 0.76; P<0.001). For the multivariable model (including eGFR at surgery, diabetes, GFR trajectory [Traj; change in eGFR during the preceding year], and proteinuria [ratio of urine protein [Upr] to urine creatinine [CR]; expressed as milligrams per deciliter]), AUC was 0.83 (95% CI, 0.77 to 0.88; P<0.001).