Glycaemic Variability as a Predictor of Graft Failure following Infra-Inguinal Bypass for Peripheral Arterial Disease. A Retrospective Cohort Study.

Background Glycaemic variability (GV), measured as the change in visit-to-visit glycated haemoglobin (HbA1c), increases the risk of multiple adverse outcomes. However, the impact of GV on graft patency following infra-inguinal bypass (IIB) is unknown. A retrospective cohort study was undertaken to assess the impact of GV on graft patency. Method A 3-year single centre retrospective case notes analysis of all people undergoing IIB between 2017-2019. Rutherford stage, graft conduit, level of bypass, procedure details, baseline demographics, co-morbidities, and GV were assessed. Time to re-intervention, ipsilateral amputation or death were recorded to determine primary patency (PP). Results 106 IIB outcomes were analysed: mean (±SD) age 68.0(9.2) years; 69(65.1%) male, 37(33.9%), 75(70.8%) had DM; 46(43.4.%) underwent elective procedures.GV>9.1% was associated with significantly lower median PP than GV<9.1%, 198 [97-753.5] vs. 713 [166.5-1044.5] days (p = 0.045).On univariate analysis, GV >9.1% vs <9.1% was significantly associated with PP (HR 1.85 [CI 1.091-3.136], p = 0.022). Bypass level was also a univariate predictor, with below knee bypasses (HR 2.31 [CI 1.164-4.564], p = 0.017), and tibial (HR 2.00 [CI 1.022-3.090], p <0.043) having lower PP than above knee bypasses. On multivariate adjustment, GV >9.1% and level of bypass remained independent predictors of primary patency, HR 1.96 (95% CI:1.12-3.42, p=0.018) and HR 2.54 (95%CI:1.24-5.22, p=0.011) respectively. Conclusions GV is an independent predictor of primary patency following infra-inguinal bypass, thus optimising GV should be a therapeutic target.