Contemporary (2009-2014) clinical outcomes after femoro-popliteal bypass surgery for chronic limb threatening ischaemia are inferior to those reported in the UK Bypass versus Angioplasty for Severe Ischaemia of the Leg (BASIL) trial (1999-2004)

Introduction: Bypass surgery (BS) remains the “gold standard” revascularisation strategy in patients with chronic limb threatening ischaemia (CLTI) due to infra-inguinal disease. The BASIL-1 trial showed that in CLTI patients who survived for 2 years or more, BS resulted in better clinical outcomes. Despite this, there has been an increasing trend towards an endovascular first approach to infra-inguinal CLTI. Our aim was to investigate whether changes in practice have impacted upon the clinical outcomes of BS in our unit ten years after BASIL-1.

Methods: Data for patients who underwent femoro-popliteal (FP) BS in BASIL-1 (1999-2004) were retrieved from trial case record forms. The comparator contemporary series (CS) comprised all patients undergoing FP BS for CLTI in our unit between 2009-2014. Demographic and clinical outcome data on CS patients were collected from the prospectively collected hospital electronic notes. Anatomic patterns of disease in the BASIL-1 and CS cohorts were scored using Bollinger and GLASS. Statistical analysis was performed in SAS v9.4.

Results: There were 128 BASIL-1 and 50 CS patients. Baseline age, gender, affected limb, and diabetes prevalence were similar, as were days spent in hospital out to 12 months and length of follow-up. BASIL-1 patients were more likely to be current smokers (p=0.000) and had a higher creatinine (p=0.04). The 30-day morbidity and mortality were higher in BASIL-1 (45.3% vs 22%, p=0.004). There was no significant difference between BASIL-1 and CS with regard to run-off Bollinger (37.7 v 32.1, p=0.167) and IP GLASS (0 vs 0, p=0.390) scores, with both groups having a median of 2 run-off vessels. Amputation free survival (62% vs 28%, HR 1.86, 95%CI 1.18-2.93, p=0.007), limb salvage (85% vs 69%, HR 2.31, 95%CI 1.14-4.68, p=0.02), overall survival (69% vs 35%, HR 1.66, 95%CI 1.00-2.74, p=0.05) and Major Adverse Limb Events (67% vs 47%, HR 1.93, 95%CI 1.15-3.22, p=0.01) were all significantly better in BASIL-1.

Conclusion: Although 30-day mortality and morbidity were significantly lower, all of the examined longer-term clinical outcomes after FP BS were significantly worse in the CS group a decade on from BASIL-1. Further research in the form of prospective cohort studies (PCS) and randomized controlled trials (RCT) is urgently required to determine if the CS data reported here are generalizable to current vascular surgical practice and, if so, to determine the reasons for these unexpected outcomes.