Long-Term Functional Patency and Cost-Effectiveness of Arteriovenous Fistula Creation under Regional Anesthesia: a Randomized Controlled Trial

Abstract

Background: Regional anesthesia improves short-term blood flow through arteriovenous fistulas (AVFs). We previously demonstrated that, compared with local anesthesia, regional anesthesia improves primary AVF patency at 3 months.

Methods: To study the effects of regional versus local anesthesia on longer-term AVF patency, we performed an observer-blinded randomized controlled trial at three university hospitals in Glasgow, United Kingdom. We randomly assigned 126 patients undergoing primary radiocephalic or brachiocephalic AVF creation to receive regional anesthesia (brachial plexus block; 0.5% L-bupivacaine and 1.5% lidocaine with epinephrine) or local anesthesia (0.5% L-bupivacaine and 1% lidocaine). This report includes findings on primary, functional, and secondary patency at 12 months; reinterventions; and additional access procedures (primary outcome measures were previously reported). We analyzed data by intention to treat, and also performed cost-effectiveness analyses.

Results: At 12 months, we found higher primary patency among patients receiving regional versus local anesthesia (50 of 63 [79%] versus 37 of 63 [59%] patients; odds ratio [OR], 2.7; 95% confidence interval [95% CI], 1.6 to 3.8; P=0.02) as well as higher functional patency (43 of 63 [68%] versus 31 of 63 [49%] patients; OR, 2.1; 95% CI, 1.5 to 2.7; P=0.008). In 12 months, 21 revisional procedures, 53 new AVFs, and 50 temporary dialysis catheters were required. Regional anesthesia resulted in net savings of £195.10 (US$237.36) per patient at 1 year, and an incremental cost-effectiveness ratio of approximately £12,900 (US$15,694.20) per quality-adjusted life years over a 5-year time horizon. Results were robust after extensive sensitivity and scenario analyses.

Conclusions: Compared with local anesthesia, regional anesthesia significantly improved both primary and functional AVF patency at 1 year and is cost-effective.

Clinical trial registry name and registration number: Local Anaesthesia versus Regional Block for Arteriovenous Fistulae, NCT01706354.

Keywords: arteriovenous access; arteriovenous fistula; chronic dialysis; chronic kidney disease.

Copyright © 2020 by the American Society of Nephrology.

Figures

Graphical abstract

Figure 1.

(A) State-transition Markov model and (B and C) nested decision trees outlining potential treatment pathways. Patients enter the decision tree in state A (new AVF creation). This state is structured as a nested decision tree depicted (A) which captures the two operative processes being compared. The AVF may successfully mature and become functional (state B); or may not reach full maturation, being in a state of primary (but nonfunctional) patency (state C) or fail completely (state D), necessitating an alternative access (state E). The patient may also die (state F). The outcome at 3 months determines the state to which the patient transitions within the Markov model. The model works in discrete time cycles of 3 months. Transition probabilities for the decision tree in state A were derived based on the previously reported 3-month primary and functional patency rates. These determined the distribution of patients across states B, C, D, and F at 3 months after the creation of a new AVF. Past this point, transition probabilities were derived from the longer-term patency rates observed at the 1-year follow-up of the original trial cohort and were assumed to apply throughout the time horizon of the model. For patients with a functional AVF (state B), there is a probability that their fistula remains functional or fails (transition to state D) that applies at each cycle as the time goes forward. For patients with a primary (but nonfunctional) AVF (state C), there is a probability that their fistula matures spontaneously and becomes functional, or matures as a result of a surgical or radiologic revision. State C is also structured as a nested tree as detailed (C). State D is an atemporal health state. Patients do not spend time in this state within the model. Instead, they are referred for a new AVF creation when the previous one fails (transition to state A), which occurs in the same cycle. This is assumed to occur up to four times in the model, i.e., a patient can have up to four new AVFs created. If the fourth AVF also fails, the patient is switched permanently to an alternative vascular access modality (TDC) until the end of the time horizon in the model. A patient can die within any given cycle in the model and get transferred to the absorption state F. For patients on dialysis, it is assumed they are dialyzing via AVF while their fistula is functional and via TDC otherwise. A proportion of the starting cohort is predialysis. This subgroup is assumed to be starting dialysis by 1 year, via AVF if a functional one is present or via TDC otherwise. While dialyzing, patients incur a risk of developing sepsis, which is dependent on the dialysis modality, and require further treatment. The incidence of infection was derived from the literature: 0.2 and 1.4 cases per 1000 dialysis days was applied for the time spent dialyzing via AVF and TDC, respectively.

Figure 2.

Trial profile and Consolidated Standards of Reporting Trials diagram demonstrating flow of participants through the trial. Follow-up and analysis figures are reported at 1 year.

Figure 3.

Base case ICER (£/QALY) was robust to variations in a wide range of model parameters. BPB, brachial plexus block; TCVC, tunneled central venous catheter.

Figure 4.

Probabilistic sensitivity analysis. Cost-effectiveness acceptability curve. BPB, brachial plexus block.

Figure 5.

Probabilistic sensitivity analysis demonstrating a high probability of RA being cost-effective compared to LA. BPB, brachial plexus block; CE, cost-effectiveness; PSA, probabilistic sensitivity analysis.