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

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.

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.

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.

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.