Economic implications of screening strategies in arteriovenous fistulae

Practice guidelines recommend performing angiography in arteriovenous fistulae (AVF) when access blood flow (Qa) is <500 ml/min, but a Qa threshold of <750 ml/min is more sensitive for stenosis. No economic evaluation has evaluated the optimal Qa threshold for angiography in AVF, or determined whether screening AVF is more economically efficient than intervening only when AVF is thrombosed. We compared two screening strategies using Qa thresholds of <750 and <500 ml/min, respectively, with no access screening. Expected per-patient access-related costs (in 2002 Canadian dollars) were $3910, $5130, and $5250 in the no screening, QA500, and QA750 arms, respectively over 5 years. Notably, screening strategies did not reduce expected access-related costs under any clinically plausible scenario. The cost to prevent one episode of AVF failure appeared to be approximately $8000–$10 000 over 5 years for both screening strategies, compared with no screening. Although the incremental cost effectiveness of screening (compared to no screening) was similar in the base case for the QA500 and QA750 strategies, the relative economic attractiveness of the QA750 strategy was adversely affected under several plausible scenarios. Also, the QA750 strategy would require many additional angiograms to prevent an additional episode of AVF failure, compared with the QA500 strategy. Screening of AVF resulted in a modest increase in net costs, and seems to require a net expenditure of ∼$9000 to prevent one episode of AVF failure. If screening is adopted, our findings suggest that angiography should be performed when Qa is <500 rather than <750 ml/min, especially when access to angiography is limited.