IYSC01 - Generalisability of the BASIL-3 Trial

Objectives: The BASIL-3 trial compared plain balloon angioplasty, drug eluting stenting and drug coated balloon angioplasty in patients with chronic limb threatening ischaemia (CLTI) secondary to primarily femoro-popliteal disease. The headline analysis of the trial did not demonstrate any difference in amputation free survival (AFS). As with all clinically driven randomised trials, generalisability of the study population is key to the interpretation of the results. Our aims were to place the BASIL-3 trial within the context of the CLTI population and investigate the generalisability of the outcome data.

Methods: As part of enhanced screening for BASIL-3 we performed a single centre, observational, prospective cohort study to document the characteristics and management of all-comers with CLTI between 2016 and 2018 at the lead BASIL-3 institution. Participants provided informed written consent. Ethical approval was sought as part of the BASIL-3 trial. Data were censored on 14th December 2022.

Results: 285 patients were admitted to the lead BASIL-3 centre with CLTI in the study time frame. Of those, 201/285 (70%) underwent revascularisation. Most of which were infrainguinal (155/201, 77%). Of these, 53 patients were randomised into BASIL-3 (53/155, 34%). This represented 19% of the total cohort of CLTI patients. The other two thirds received revascularisation outside of the trial. Those receiving endovascular treatment in BASIL-3 had similar AFS to those undergoing vein bypass at the same institution. However, those who underwent endovascular treatment outside of BASIL-3 had much worse AFS (p <.001).

Conclusions: Patients with CLTI secondary to femoropopliteal disease who were randomised into BASIL-3 in our study are likely to represent a third of patients with infrainguinal disease. The results of this robust trial are therefore likely to be generalisable to similar cohorts of CLTI patients. Patients randomised into BASIL-3 were not at overtly high risk of limb loss as AFS was equivalent to patients undergoing vein bypass at our institution.