Choice of vascular access among incident hemodialysis patients: a decision and cost-utility analysis

Abstract

Background and objectives: Arteriovenous fistulas (AVFs) are widely accepted as the preferred hemodialysis vascular access type. However, supporting data have failed to consider morbidity and mortality incurred during failed creation attempts and may therefore overstate potential advantages. This study compares survival, quality-adjusted survival, and costs among incident hemodialysis patients after attempted placement of AVFs or arteriovenous grafts (AVGs).

Design, setting, participants, & measurements: Analogous Markov models were created, one each for AVF and AVG. Patients entered consideration at the time of first access creation, contemporaneous with dialysis initiation. Subsequent outcomes were determined probabilistically; transition probabilities, utilities, and costs were gathered from published sources. To ensure comparability between AVFs and AVGs, the timing and likelihood of access maturation were measured in a contemporary cohort of incident hemodialysis patients.

Results: Mean (SD) overall survival was 39.2 (0.8) and 36.7 (1.0) months for AVFs and AVGs, respectively: difference (95% confidence interval [CI]) 2.6 (1.8, 3.3) months. Quality-adjusted survival was 36.1 (0.8) and 32.5 (0.9) quality-adjusted life months (QALMs) for AVFs and AVGs, respectively: difference (95% CI) 3.6 (2.8, 4.3) QALMs. The incremental cost-effectiveness ratio (95% CI) for AVFs relative to AVGs was $446 (-6023, 6994) per quality-adjusted life year saved.

Conclusions: AVFs are associated with greater overall and quality-adjusted survival than AVGs. Observed differences were much less pronounced than might be expected from existing literature, suggesting that prospective identification of patients at high risk for AVF maturational failure might enable improvements in health outcomes via individualization of access planning.

Figure 1.

Conceptual model. (a) In the base-case, the decision was modeled as a choice between AVF and AVG. (b) Subsequently, patients transitioned among states of maturing access, functional access, catheter commitment, and death in probabilistic fashion using analogous Markov models.

Figure 2.

Proportion of subjects in each state over study time. State probabilities in (a) the AVF arm and (b) the AVG arm.

Figure 3.

One-way sensitivity analyses. (a) Effects of varying the likelihood of AVF maturation on overall survival. (b) The effect of varying the relative risk of mortality with functioning AVG on overall survival.

Figure 4.

Two-way sensitivity analysis based on the utility of AVFs and utility of AVGs (before application of disutilities for percutaneous/surgical interventions and blood stream infections). Outcome is quality-adjusted survival. White areas represent values that favor AVGs; gray areas represent values that favor AVFs. For the model to favor AVGs, the utility for AVGs must be between 0.09 and 0.15 higher than the utility of AVFs.

Figure 5.

Cost-utility plane comparing AVFs to AVGs. Estimates from individual estimates are indicated by points; the 95% confidence bounds are indicated by dashed lines.