A Scoring System (DISTAL) for Predicting Failure of Snuffbox Arteriovenous Fistulas

ObjectivesA first fistula failing will lead to serious morbidity in a proportion of patients. Snuffbox fistulas have the advantage of proximal vessel preservation, and although several factors have been associated with failure, the relative importance of these factors combined and their clinical applicability is unknown. The aim of this study was to determine the relative importance of risk factors for snuffbox fistula failure and create a simple scoring system to aid fistula placement decision making.Methods218 consecutive patients were examined using Cox regression analysis to determine risk factors for failure. Primary patency was used as the endpoint.ResultsDiabetes, IHD, Stroke, Two snuffbox procedures, Age > 70 and Less than 2.0 mm vein (DISTAL, maximum score 6) were significant predictors of primary patency failure. There was a clear decrease in primary patency with increasing DISTAL score (log rank χ2 = 30.3, DF = 5, P < 0.001). Performing snuffbox procedures on patients with a score ≤3 would give a 23% reduction in the number of failures within two months for a 12% reduction in the number of patients offered snuffbox procedures.ConclusionThe DISTAL scoring system could give large improvements in primary patency for the snuffbox fistula if the results can be validated in other datasets.