This project has identified the following priority areas for future research:
- Evaluation of implementation of strategies using the ADD-RS and D-dimer test in clinical practice.
We identified two strategies that use the ADD-RS and D-dimer to select patients for CTA and could be cost-effective in the NHS. However, our conclusions were limited by uncertainty around how the strategies would be implemented in practice, specifically in terms of how clinicians would select patients with a significant probability of AAS and how the strategies would be used alongside clinical judgement to influence decision-making. We, therefore, recommend evaluation to determine the effects of using these strategies upon CTA ordering, AAS diagnosis, patient outcomes and healthcare costs.
- Research into how clinicians use their judgement to determine whether to suspect AAS.
As above, clinical judgement needs to be used to determine whether patients have suspected AAS and need investigation. We currently know very little about how clinicians make this judgement, whether their judgements are accurate and what factors influence their judgement. Research is, therefore, required to improve our knowledge of clinical judgement in the assessment of AAS and potentially to determine how clinicians can identify patients requiring investigation for AAS. Research could also explore how clinicians incorporate information from the ADD-RS and D-dimer into their decision-making.
- Evaluation of the diagnostic accuracy of biomarkers other than D-dimer.
We identified many low-quality studies evaluating a wide range of biomarkers. Only 11 cohort studies were identified for inclusion in our review, and most of the excluded case-control studies used selected control groups that are likely to bias estimates of diagnostic accuracy. The findings from the 11 cohort studies were limited and inconsistent. We, therefore, recommend that future research should evaluate potential biomarkers for AAS in a large cohort study with a sufficient number of cases of AAS to estimate sensitivity with acceptable precision. This is likely to require a multicentre study and potentially international collaboration. The study should also record the ADD-RS and D-dimer so that analysis can determine how biomarkers add to current assessment with the ADD-RS and D-dimer.
- Research into diagnostic pathways for people with previous AAS or known aneurysm.
This research recommendation did not arise directly from our study but was identified as a priority by our PPI group. They noted that people with previous AAS or known thoracic aortic aneurysm are at increased risk of AAS but may also have concerns about symptoms that make them more likely to present to hospital. We identified very little evidence relevant to this population. We noted that D-dimer measurement could be helpful in identifying a new or recurrent AAS, whereas the ADD-RS may have a more limited role in clinical probability estimation than in the general population. We, therefore, recommend further research to determine how diagnostic strategies for suspected AAS apply to people with previous AAS or known thoracic aortic aneurysm.