The perceived usefulness of registries is that they are a pragmatic and representative tool to assess the impact of new treatments as they are introduced into practice. They give information on outcomes, learning curves and dissemination of the new technique, though the validity of the results is often viewed with suspicion because they are voluntary and observational. The results from a number of randomised controlled trials (RCTs) of Endovascular Aneurysm Repair (EVAR) are now available to compare with the outcomes contained within registries; such a comparison has been carried out by Leurs et al.
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Leurs identified patients in the EUROSTAR cohort with risk factors similar to those in the Dutch Randomised Endovascular Aneurysm Management (DREAM) trial. A group of 856 EUROSTAR patients were selected based on ASA distribution and matched to those in the DREAM trail. Outcomes from the registry and RCT are strikingly similar, supporting the case that the registry data is a valid representation of EVAR outcomes and the DREAM trial results are generalisable. Should we be surprised at this, probably not. The weaknesses of observational methods may have been overemphasised, with a number of reports now showing that as long as the methodological weaknesses are recognised and limited, either by design or analysis, observational study outcomes are as valid as more explanatory RCTs.
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Leurs et al's findings strengthen the case for the use of registries to assess new techniques, and that in the case of EVAR the use of registries was worthwhile. This is important as device technology continues to develop rapidly and long-term device related complications remain problematic. Further large randomised trials for EVAR in AAA are unlikely, at least in the near future, yet the registries remain as important ongoing tools. The problem with the EVAR registries is the lack of collection of data for the comparator treatment conventional open repair, and so it is not possible to perform a true cohort study; a problem that could be addressed by establishing larger or linked databases. In the UK, the National Vascular Database collects data for both open repair and EVAR, and with appropriate information technology and web-based systems, it should be possible to ensure registry data for the UK registry of Endovascular Treatment of Aneurysms (RETA) is collected and comparator data for open repair obtained to allow comparisons in the future. Similar databases could be extended across Europe and provide a model for assessment of new techniques. Such well designed and maintained registries could produce evidence negating the need for some trials, saving time and expense, particularly if areas of uncertainty are explored using other methods such as computer modeling.
To enable this to occur requires a sound financial base to provide the appropriate infrastructure to establish, maintain and analyse registries. In the UK the National Institute for Health and Clinical Excellence recommend that EVAR cases are submitted to an existing registry,
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yet this organization has no formal arrangements to help maintain registries. The recent announcement of the closure of the EUROSTAR registry shows that without adequate financial support, such valuable resources, and their ability to inform practice, are easily lost.IPG163 Stent-graft placement in abdominal aortic aneurysm – guidance, 22.
http://www.nice.org.uk/download.aspx?o=IPG163guidance
Date: March 2006
References
- Impact of study design on outcome after endovascular abdominal aortic aneurysm repair. A comparison between the randomized controlled DREAM-trial and the observational EUROSTAR-registry.Eur J Vasc Endovasc Surg. 2007; 33: 172-176
- A comparison of observational studies and randomized, controlled trials.New Engl J Med. 2000; 342: 1878-1886
- Randomized, controlled trials, observational studies, and the hierarchy of research designs.New Engl J Med. 2000; 342: 1887-1892
- Methods in health services research. Interpreting the evidence: choosing between randomised and non-randomised studies.BMJ. 1999; 319: 312-315
- IPG163 Stent-graft placement in abdominal aortic aneurysm – guidance, 22.(Available at:)http://www.nice.org.uk/download.aspx?o=IPG163guidanceDate: March 2006
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Publication history
Published online: July 09, 2007
Accepted:
March 20,
2007
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© 2007 European Society for Vascular Surgery. Published by Elsevier Inc.
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- Impact of Study Design on Outcome after Endovascular Abdominal Aortic Aneurysm Repair. A Comparison between the Randomized Controlled DREAM-trial and the Observational EUROSTAR-registryEuropean Journal of Vascular and Endovascular SurgeryVol. 33Issue 2
- PreviewPatients with abdominal aortic aneurysm (AAA) can be treated by transfemoral endovascular intervention and by conventional open surgery. Level-one evidence of the safety and efficacy of one treatment mode over the other is only provided by a randomised controlled trial (RCT). Results reported by voluntary registries are considered less valid than data from RCTs. On the other hand the outcome of a RCT may not be generalisable to the common practice because of vigorous selection of patients and institutions.
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