Subgroup variations in effectiveness of femoropopliteal sirolimus versus paclitaxel-coated balloon angioplasty: post hoc results of the randomised SIRONA trial

Abstract

INTRODUCTION: The randomised SIRONA trial showed that sirolimus-coated balloon (SCB) angioplasty was non-inferior to paclitaxel-coated balloon angioplasty (PCB) regarding femoropopliteal primary patency. There was no difference in clinically driven target lesion revascularisation (cdTLR) rates between the treatment groups. This post-hoc analysis aimed to assess whether the overall results were consistent across different subgroups and selected post-baseline factors. METHODS: Primary patency at 12 months was assessed using duplex ultrasound and adjudicated by a core laboratory for 203 and 199 participants in the SCB and PCB groups, respectively (available-case intention-to-treat analysis). Data on 12-month cdTLR were available for 238 and 244 participants in the SCB and PCB groups, respectively. Odds ratios (ORs) for primary patency and hazard ratios (HRs) for cdTLR after SCB compared to PCB in non-pre-specified subgroups were assessed using generalised linear mixed models to control for centre effects, and Cox proportional hazards models, respectively. RESULTS: Primary patency and cdTLR were generally consistent across the analysed subgroups. Two nominal interaction signals were observed. For cdTLR, a nominal interaction with age was identified (interaction p = 0.047); among participants older than 70 years, the estimated hazard ratio favoured SCB (HR 0.52, 95% CI 0.16-1.71). For primary patency, treatment effects differed according to residual diameter stenosis (interaction p = 0.022); the estimated treatment effect favoured SCB in participants with residual diameter stenosis > 30% (OR 1.67, 95% CI 0.76-3.65). No other interactions between treatment and subgroup or post-baseline factors were observed. CONCLUSION: The effectiveness of SCB compared to PCB was similar and mainly consistent among subgroups. The evaluation should be considered exploratory. TRIAL REGISTRATION: ClinicalTrials.gov, NCT04475783. Registered 17 July 2020, https://clinicaltrials.gov/study/NCT4475783 .