Type B aortic dissection (TBAD) is a treatable life-threatening condition with an associated 30-day mortality of 13.3% in the acute phase, which can occur in all age groups. Incidence of acute TBAD has been reported to be between 0.5 – 6.3 per 100,000 person-years, with an overall increasing trend. Within the United Kingdom (UK), it is estimated that the annual incidence will increase dramatically with a projected doubling from 3,892 in 2010 to as many as 6,893 by 2050. The mainstay of management for uncomplicated TBAD is medical therapy with tight blood pressure control and optimisation of haemodynamics and invasive monitoring, it is estimated that this is achievable in approximately 75% of cases in the initial phase, although these treatments are not evidence-based. However, sufficient aortic remodelling to prevent aneurysm dilatation occurs in as few as 25% of these patients over a 5-year surveillance period. Hence, the associated increasing prevalence of chronic TBAD represents a substantial source of morbidity and resource use.
There has been a long-running voluntary registry of patients with aortic dissection (IRAD) and a few randomised controlled trials of intervention led by vascular surgeons but these all focus on outcomes such as mortality, aortic remodelling, aneurysm formation and the medical complications of endovascular intervention and the views of other stakeholders, particularly the patient and community health care have not been well represented.
Despite a sparsity of relevant randomised-controlled trials (RCTs), the indication for treatment for complicated acute TBAD is generally agreed by key stakeholders with a lack of equipoise in delaying surgical intervention. This particularly so with endovascular thoracic stent grafts becoming a viable treatment option for acute complicated TBAD from 1999. However, the consensus and evidence supporting surgical intervention to promote aortic remodelling in subacute/chronic TBAD is inconclusive due to the troubling associated complications including stroke, paraplegia, and retrograde type A dissection. This is reflected in international guidelines such as the European Society for Vascular Surgery (ESVS) “Management of Descending Thoracic Aorta Diseases” recommending “…patients at risk of further aortic complications with suitable anatomy for endografting, endovascular repair of uncomplicated chronic type B aortic dissection should be considered…” (IIa B).
In response to this, the National Institute for Health Research have issued a commissioned call for trials assessing the role of TEVAR in comparison to best medical management for subacute / chronic TBAD. Given the need for future evidence, careful consideration of outcome measures for interventions in TBAD is needed. Consensus on outcome reporting would permit future evidence synthesis and improve efficiency for detecting high-risk disease patterns.
Hence, we aim to produce a distinct (but likely overlapping) set of core outcome measures to represent key stakeholders and improve subsequent compilation of evidence for acute and chronic presentations of TBAD. We note that accepted definitions of outcomes have been previously sought (https://www.comet-initiative.org/Studies/Details/714), however this is distinct from a core outcome set to guide future RCTs.
G Lopez-Pena1 (Principal investigator)
M Machin1
L Hanna1
Graham Cooper2
Santi Trimarchi3
Kevin Mani 4
J Powell1
R Gibbs1
C Bicknell1
1, Department of Surgery & Cancer, Imperial College London, UK
2, Cardiology and Cardiothoracic Surgery, Sheffield University, UK
3, Cardiovascular Center, IRCCS Policlinico San Donato, Italy
4, Department of Surgical Sciences, Vascular Surgery, Uppsala University, Sweden
Disease Category: Heart & circulation
Disease Name: Type B aortic dissection
Age Range: 18 - 120
Sex: Either
Nature of Intervention: Other, Surgery
- Charities
- Clinical experts
- Families
- Patient/ support group representatives
- Researchers
- Other
- Service providers
- COS for practice
- Consensus meeting
- Delphi process
- Focus group(s)
- Interview
- Survey
- Systematic review
- Semi structured discussion
Development of core outcome sets for acute and chronic TBAD will follow a multi-step iterative process. This can be summarised in the following stages:
1. Systematic review of the literature
2. Focus group meeting with patients and/or surveys of other stakeholders
3. Acceptability survey / pilot Delphi
4. Delphi process for prioritisation of outcomes
5. Consensus meeting
Initially, a systematic review of the literature of studies reporting on the outcomes of TBAD will be undertaken to establish the breadth of outcomes reported to date. Focus groups, consisting of patients with TBAD and their caregivers, will be undertaken to gain insight into their views and the importance of patient-reported outcomes. From these inputs, according to the COMET initiative, all outcomes will be categorised and listed. A pilot Delphi survey will be constructed and circulated to key stakeholders to establish acceptability and identify potential missing outcome measures. After iteration, an international Delphi survey will be circulated. Results from this will be used to guide expert consensus meetings and orchestration of core outcome sets for studies investigating treatments for TBAD.