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Evidence level for peripheral vascular intervention recommendations varies
The evidence level behind the current American Heart Association/American College of Cardiology guidelines for peripheral vascular interventions varies significantly, underscoring the need for higher-quality evidence in this area, according to a study published in Circulation: Cardiovascular Interventions.
“The number of endovascular interventions performed for peripheral vascular disease has increased substantially over the past decade and AHA/ACC guideline recommendations help inform their use. Nevertheless, the quality of evidence supporting these guideline recommendations has not been well studied,” Partha Sardar, MD, interventional cardiology fellow at Warren Alpert Medical School at Brown University, and Herbert Aronow, MD, MPH, FACC, FSCAI, FSVM, director of interventional cardiology at the Lifespan Cardiovascular Institute and director of the cardiac catheterization laboratories at Rhode Island and The Miriam Hospitals, Warren Alpert Medical School at Brown University, wrote in an email to Cardiology Today’s Intervention.
Sardar, Aronow and colleagues identified 134 recommendations from five current full guidelines for endovascular and surgical procedures for peripheral vascular disease. For all peripheral vascular interventions, only 13% of recommendations were supported by level A evidence, whereas 48% were supported by level B evidence and 39% were supported by level C evidence.
The majority of recommendations were supported by level C evidence for pulmonary embolism or deep vein thrombosis interventions (76%) and inferior vena cava filter placement (69%), and level B evidence for renal artery stenosis interventions (67%).
However, levels of evidence were higher for endovascular therapy for stroke (level A, 24%; level B, 52%; level C, 24%), carotid revascularization (level A, 23%; level B, 52%; level C, 24%) and endovascular or surgical treatment for abdominal aortic aneurysm and lower-extremity aneurysm (level A, 26%; level B, 67%; level C, 7%). Quality of evidence for surgical revascularization for lower-extremity peripheral artery disease (level A, 18%; level B, 37%; level C, 45%) was also lower than for endovascular therapy (level A, 18%; level B, 55%; level C, 27%).
“We were most surprised by the degree of variation in level of evidence supporting different procedural guideline recommendations. For example, there was no level A evidence to support pulmonary embolism/deep vein thrombosis, inferior vena cava filter or renal artery stenosis intervention. In contrast, nearly 1 in 4 endovascular stroke therapy recommendations were supported by level A evidence,” Sardar and Aronow said.
Strength of recommendations
The researchers also noted that, overall, most recommendations were class II (54%), followed by class I (35%) and class III (11%).
For lower-extremity PAD endovascular revascularization, IVC placement, carotid revascularization and endovascular therapy for stroke, most recommendations were class II rather than class I or class III. For renal artery stenosis revascularization, recommendations were split evenly between class I and class II, with none falling into class III. For surgical or endovascular treatment of PE, there were no class I recommendations and 80% were class II. The classes of recommendation also varied for other peripheral vascular interventions, including DVT interventions, endovascular or surgical treatment for mesenteric artery disease, interventions for subclavian and brachiocephalic arteries, and endovascular or surgical treatment for AAA or lower-extremity aneurysms .
Results also showed significant variation in the strongest recommendation (class I-A) between procedures:
- 24% for endovascular therapy for stroke;
- 18% for endovascular or surgical revascularization for lower-extremity PAD;
- 20% for endovascular or surgical treatment for aneurysms of the abdominal aorta and the lower extremities; and
- 0% for all other peripheral vascular interventions.
The most common recommendation for all peripheral vascular interventions was class II-C (27%), followed by class II-B (26%).
Changes over time
From the 2005 to 2011 guidelines, the researchers observed some changes in the total number of recommendations.
For lower-extremity PAD, the number of recommendations decreased from 20 to 11 for endovascular therapy and from 29 to 11 for surgery. There were no increases in recommendations supported by level A evidence for either treatment, but the number of class I indications decreased from 10 to three for endovascular therapy (P = .27) and from 19 to five for surgical revascularization (P = .29).
For endovascular stroke therapy, there were no major changes in the number of recommendations or in level A evidence. However, level B evidence increased and level C evidence decreased.
The variation in the guidelines indicates that many recommendations in this area are based on lower level of evidence or expert opinion, according to the researchers.
“Most AHA/ACC endovascular procedural recommendations are not supported by level A evidence. This observation does not speak to the appropriateness of these procedures but rather the need for further study. It is incumbent upon industry, government and academic clinicians to rigorously study the safety, efficacy and cost-effectiveness of available and future endovascular therapies,” Sardar and Aronow said.
Gaining a broader perspective would also be beneficial to understanding the scope of the problem, according to Sardar and Aronow.
“Our study focused on AHA/ACC guidelines, but it would be equally informative to apply similar questions to clinical practice guidelines from other U.S. and international organizations. More importantly, we would like to see a greater number of randomized studies performed in this arena in hopes of producing additional Level A evidence to better support current and future guideline recommendations,” they told Cardiology Today’s Intervention.
New avenues for research
In an accompanying editorial, David W. Lee, MD, and Matthew A. Cavender, MD, MPH, both from the University of North Carolina at Chapel Hill, echoed the researchers’ concerns about the need for better evidence.
These study results, however, also highlight potential avenues for improving research efforts, according to Lee and Cavender. For instance, research networks that facilitate comparative effectiveness studies in patients with peripheral vascular disease could help advance the field. Furthermore, the clinical trial infrastructure put in place for ongoing studies such as BEST-CLI and CREST-2 could provide a framework for additional studies in PAD, they wrote, and multidisciplinary initiatives such as the Pulmonary Embolism Response Team Consortium can help secure funding for high-quality research.
“Finally, the academic community must develop more cost-effective ways in which to generate high-quality comparative effectiveness research,” Lee and Cavender wrote, noting that the use of existing registries, as well as improving data collection within these registries, could supply important information.
The overarching goal of research in this field is to determine which treatments are most effective for which patients and clinical trial findings enable physicians to develop ways to implement treatment strategies into clinical practice, according to Lee and Cavender.
“Thus, improvements in the quality of comparative effectiveness form the foundation upon which clinical practice guidelines, the development of performance measures to help identify areas of deficiency and success, and initiatives to improve the quality of health care delivery are built,” they wrote. “The stagnant evidence base for clinical practice guidelines over the past decade calls for a significant need for high-quality comparative effectiveness research in the arena of peripheral vascular interventions. Just like patients with lower-extremity PAD who experience from claudication, efforts to continue comparative effectiveness research in peripheral interventions need to continue moving forward.” – by Melissa Foster
For more information:
Herbert Aronow, MD, MPH, FACC, FSCAI, FSVM, can be reached at herbert.aronow@lifespan.org.
Disclosures: Aronow and Sardar reports no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures. Cavender reports he has received research support from AstraZeneca, Bristol-Myers Squibb, Chiesi, GlaxoSmithKline, Novartis, Takeda and The Medicines Company, and he has received consultant fees from AstraZeneca, Boehringer Ingelheim, Chiesi, Edwards Lifesciences, Janssen, Merck and Sanofi-Aventis. Lee reports no relevant financial disclosures.
Perspective
Back to TopEach of us has heard the statement “What do the guidelines say?” on rounds. This question reflects the opinion held by many physicians that a ‘guideline-concordant’ therapy must be the best as experts in the field have vetted and recommended it. We tout the term ‘evidence-based medicine’ as the only option for our patients; yet, how often do we know the level of evidence behind each guideline recommendation when we institute our care plans? As noted by Lee and Cavender in the accompanying editorial, guidelines ‘guide’ clinicians on what therapies to choose for patients, permit prioritization of costly interventions and form the basis for quality metrics. If the guidelines are lacking real evidence, then how can they guide us or become the foundation of metrics upon which we will be judged?
In this important paper by Sardar et al in Circulation: Cardiovascular Interventions, the authors dive deep into the AHA/ACC guidelines on Endovascular and Surgical Treatment of Peripheral Vascular Disease answering the follow-up questions that most of us do not even ask. The results are disturbing. The authors (all recognized experts in the arena of PAD) report that of the 134 recommendations, a level A evidence supported only 13% and 39% were supported by level C evidence. Most of the guideline recommendations were class II (54%) with only 1 in 3 (35%) being class I. They further identify serious gaps in the level of evidence in the specific arenas of venothromboembolic disease (PE, DVT therapy and IVC filter placement) as well as renal artery stenosis therapy.
This study underscores the need for more high-quality evidence for our patients with peripheral vascular disease who already are often not treated optimally with respect to medical therapy. But how do we get this evidence? Lee and Cavender provide a suggestion of creating a research network that would permit comparative effectiveness research for patients with peripheral vascular disease akin to the Cardiothoracic Surgery Network established by the NHLBI. Regardless of the manner, this paper is a sobering reminder that perhaps what the guidelines suggest may just not be based on robust data and demands each of us to read not just the recommendation, but what the data behind it are. Otherwise, we will be standing on unsteady ground when we ask that question on rounds. In the meantime, we need to get going and get more data.