Predicting outcomes in native AV forearm radio-cephalic fistulae; the CAVeA2T2 scoring system.

Purpose: The aim of this study was to identify significant factors relating to fistula survival and create an easy-to-use scoring system for predicting fistula patency rates.
Methods: A total of 276 consecutive radio-cephalic forearm fistulae created in a single tertiary vascular unit were identified retrospectively. Numerous patient- and fistula-related demographics were noted. Cox regression analysis was used to identify significant factors predictive of reduced fistula patency rates, and significant variables weighted according to their hazard ratio.
Results: Five significant factors were identified: ipsilateral Central venous access, Age >73 years, anastomosed Vein <2.2 mm, previous lower limb Angioplasty and absent intra-operative Thrill (1 point for first three variables, 2 points for the latter two). The CAVeA2T2 score (maximum 7 points) significantly predicted for reduced fistula patency (p = 0.001) and a reduced rate of successful dialysis (p = 0.001). Fistulae with CAVeA2T2 scores ≥2 had 6 week and 1 year patency rates significantly below pooled published rates. Without scoring for thrill, that is in the pre-operative setting, the scoring system remained significant at all stages.
Conclusion: The CAVeA2T2 scoring system is a potential scoring system for predicting fistula patency rates and the likelihood of dialysing through a fistula. Further studies and/or external validation is required in the context of methodological limitations. How to manage patients with a high CAVeA2T2 score is unknown.