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21/585 Early endovascular repair in type b uncomplicated sub-acute aortic dissection commissioning brief

Contents

Introduction

The aim of the HTA Programme is to ensure that high quality research information on the clinical effectiveness, cost-effectiveness and broader impact of healthcare treatments and tests are produced in the most efficient way for those who plan, provide or receive care from NHS and social care services. The commissioned workstream invites applications in response to calls for research on specific questions which have been identified and prioritised for their importance to the NHS, patients and social care.

Research question

What is the clinical and cost-effectiveness of early thoracic endovascular aortic repair in uncomplicated type b sub-acute aortic dissection compared to optimal medical treatment?

  1. Intervention: Thoracic endovascular aortic repair (TEVAR)
  2. Patient group: Adults with an uncomplicated type B sub-acute aortic dissection. Applications are encouraged which include recruitment from geographic populations with high disease burden which have been historically underserved by research activity in this field and should include all people eligible for recruitment.
  3. Setting: Major vascular centres with TEVAR experience (and geographical spread across the UK).
  4. Comparator: Medical treatment (to be defined by applicants).
  5. Study design: A randomised controlled trial with an internal pilot phase to test key trial processes such as recruitment and adherence. Clear stop/go criteria should be provided to inform progression from pilot to full trial.
  6. Important outcomes: Aorta-related mortality; all-cause mortality; hospital admissions; cost-effectiveness; quality of life (to be selected, defined, and justified by applicants).
  7. Other outcomes: Aortic remodelling, adverse events; disease progression (e.g. aortic rupture, aortic dilation.)
    Existing Core Outcomes should be included amongst the list of outcomes unless a good rationale is provided to do otherwise. Applicants are encouraged to report recruitment and findings disaggregated by sex (and other demographic factors where relevant).
  8. Minimum duration of follow-up: 5 years. Researchers should obtain consent to allow future follow up through efficient means (such as routine data).

Rationale

The aorta is the largest artery of the body distributing arterial blood to the periphery, at high pressure from the heart. An acute aortic dissection is a medical emergency, caused by a partial tear within the middle layer of the aortic wall. This can interrupt blood flow to vital organs, which if left untreated can rupture. If dissection occurs in the descending aorta, it is called a type b dissection, which can either be complicated or uncomplicated (uTBAD).

Complicated type b dissections are usually treated through thoracic endovascular aortic repair (TEVAR) to stent the aorta and prevent further tearing, whilst uTBAD is mostly treated with conservative medical therapy to control pain, blood pressure and heart rate, with close surveillance. As the disease progresses, highly complex open surgery may be required, with less favourable outcomes due to likelihood of aneurysm formation, malperfusion syndrome (loss of blood supply to vital organs) and progressive remodelling of the aorta (changes to the artery after injury).

In the UK some uTBAD patients are treated with an early TEVAR as a preventative measure, however weak evidence is available to support its use. There is 1 relevant randomised control trial which identified no improvement in survival at 2 years, however it found reduced aorta-related mortality at 5 years. The variation in approach across the UK is varied, mostly dependant on geography and experience of the surgeon. It is, therefore, not known whether early intervention is optimal compared to conservative medical therapy alone. An adequately powered RCT is required to identify whether early intervention through TEVAR is clinically beneficial in patients with uTBAD which can be used to inform clinical practice (either endorse its use or prevent future use) within the NHS.

Additional commissioning brief background information

A background document is available that provides further information to support applicants for this call. It is intended to summarise what prompted the call and the existing evidence base, including relevant work from the HTA and wider NIHR research portfolio. It was researched and written on the basis of information from a search of relevant sources and databases, and in consultation with a number of experts in the field. If you would like a copy please email htaresearchers@nihr.ac.uk.

Making an application

If you wish to submit a Stage 1 application for this call, the online application form can be found on the funding opportunities page. To select this call, use the filters on the right of the screen or search using the call name and/or number.

Your application must be submitted on-line no later than 1pm on the 30 March 2022. Applications will be considered by the HTA Funding Committee at its meeting in May 2022.

Guidance notes and supporting information for HTA Programme applications are available.

Important: Shortlisted Stage 1 applicants will be given eight weeks to submit a Stage 2 application. The Stage 2 application will be considered at the Funding Committee in September 2022.

Applications received electronically after 1300 hours on the due date will not be considered.

For commissioned topics, the Programme strongly discourages the practice of the same co-applicant joining more than one competing team. There may be unusual circumstances where the same person could be included on more than on application eg a lead from a named charity or a unique national expert in a condition.

For such exceptions (i) each application needs to state the case as to why the same person is included (ii) the shared co-applicant should not divulge application details between teams and (iii) both teams should acknowledge in their application that they are aware that one of their co-applicants is part of a competing application and that study details have not been shared.

Should you have any queries please contact us by email: htacommissioning@nihr.ac.uk