Duplex Ultrasound Surveillance Trial after Endo Revascularisation - feasibility randomised controlled trial(DUSTER)

Research question What is the feasibility, acceptability and impact on clinical decision making of implementing an integrated ultrasound surveillance programme for patients after lower limb endovascular therapy?

Background In the UK, each year, 4000 major amputations are performed for chronic limb threatening ischaemia (the end stage of peripheral arterial disease).

The mainstay of treatment is endovascular therapy, with 17, 000 catheter-based procedures performed in the NHS annually. These procedures have a restenosis risk of 50% over 2-years which can lead to limb loss.

In 2019, European guidelines recommended an ultrasound surveillance programme after endovascular therapy but with no evidence of feasibility, acceptability, impact on clinical decision making or better limb salvage.

The NHS has not adopted ultrasound surveillance and our clinician survey demonstrated 83% rely on clinical surveillance alone.

Our meta-analysis of studies comparing standard clinical follow up with integrated clinical plus ultrasound follow up showed 2 small non-randomised, low-quality trials with a high risk of bias. They suggested 1 in 5 amputations could be prevented through the introduction of ultrasound surveillance.

Aims and Objectives DUSTER tests the feasibility of introducing integrated ultrasound surveillance into the NHS and will answer: What is the patient acceptability of ultrasound surveillance? Which components of ultrasound surveillance are feasible? Does ultrasound surveillance impact clinical decisions to re-intervene?

What are the barriers to ultrasound surveillance? Methods DUSTER is a mixed methods study.

Phase 1: 2 site feasibility RCT (1 urban, 1 rural), 1:1 randomisation P- 70 adults with chronic limb threatening ischaemia who have had successful lower limb endovascular therapy I – 1-year integrated ultrasound plus clinical surveillance programme at 1, 6 and 12 months C – standard clinical surveillance at 1, 6 and 12 months by a vascular specialist O – Process endpoints: % uptake of ultrasound appointments, technical completion rates of ultrasound components and re-intervention rates in both arms.

Secondary endpoints are complications of re-interventions, limb salvage, amputation free survival, pain scores, EQ5D, VascuQoL-6, Barthel index of independence and major adverse cardiac and cerebrovascular events.

Phase 2: Independent semi-structured interviews with intervention arm participants This will explore barriers and facilitators to ultrasound surveillance and effect on patients lives. Both attenders and non-attenders with be invited. A qualitative descriptive research methodology will be used.

Phase 3: HTA application co-design This will include 2 separate focus groups of participants and clinical stakeholders to help co-design the primary endpoint for HTA application, if the progression criteria are met.

Outputs The findings of the study will be published in peer-reviewed journals and presented at British and European meetings. A plain English summary will be emailed to patients and a plain English video posted on social media.

DUSTER will inform an HTA application for a multicentre RCT to evaluate the clinical and cost-effectiveness of integrated ultrasound surveillance.