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Balk E, Raman G. Comparative Effectiveness of Management Strategies for Renal Artery Stenosis: 2007 Update [Internet]. Rockville (MD): Agency for Healthcare Research and Quality (US); 2007 Nov. (Comparative Effectiveness Reviews, No. 5.)

1Introduction

The Tufts-New England Medical Center Evidence-based Practice Center (EPC) completed the report on Comparative Effectiveness of Management Strategies for Renal Artery Stenosis1 with a simultaneous publication, Comparative Effectiveness of Management Strategies for Renal Artery Stenosis: A Systematic Review,2 in December 2006. Those documents evaluated the evidence on various interventions for, and the natural history of, atherosclerotic renal artery stenosis (RAS) in adults. The literature searches were performed through September 2005. The systematic review included all studies of patients with atherosclerotic RAS (ARAS) that compared two or more interventions, recent prospective cohort studies (single arm, non-comparative) of angioplasty with stent placement, prospective cohort studies of medical interventions, recent cohort studies of ARAS natural history, and prospective or large retrospective, recent studies of surgical bypass interventions. The Centers for Medicare and Medicaid Services (CMS) requested an update to the original report for the purpose of a Medicare Evidence Development & Coverage Advisory Committee (MedCAC) meeting on renal artery stenosis in July 2007. The original review and this update were conducted to clarify the current state of the literature and science and to better understand the state of evidence.

As described in greater detail in the Methods section, this update used the same eligibility criteria for studies. As with the original report, it is important to note that the reviewed studies did not explicitly address the population of patients who may need acute intervention because of rapid clinical deterioration, the conclusions of this review do not apply to these patients. In addition, this report does not address the management of fibromuscular dysplasia, renal transplant recipients, or patients who have a previous, failed revascularization.

This report represents an update and summary of the original report. Sections of the original report and the Annals of Internal Medicine article are copied here, but many of the specifics of that report are not repeated. This document focuses more on the conclusions reached from the (updated) systematic review than the details of the reviewed articles or the findings. This document is not meant to supplant or replicate the original report. Reference to the full report may be necessary for details. This document does not repeat information about the ongoing Cardiovascular Outcomes in Renal Atherosclerotic Lesions (CORAL) trial.3 Updated versions of the summary tables are provided as an appendix to this document.

Background

This section is largely reproduced from Balk et al. in the Annals of Internal Medicine.2

RAS is defined as the narrowing of the lumen of the renal artery. Atherosclerosis accounts for 90 percent of cases of RAS.4 ARAS is a progressive disease that may occur alone or in combination with hypertension and ischemic kidney disease.4 The prevalence of ARAS ranges from 30 percent among patients with coronary artery disease to 50 percent among elderly or those with diffuse atherosclerotic vascular diseases.5,6 In the United States 12 to 14 percent of new patients entering dialysis programs have been found to have ARAS, although the contribution of ARAS to end stage renal disease is unclear.7

Most authorities consider the goals of therapy to be improvement in uncontrolled hypertension, preservation or salvage of kidney function, and improvement in symptoms and quality of life.8,9 Treatment alternatives include medications alone or revascularization of the stenosed renal artery or arteries. Combination therapy with multiple antihypertensive agents, usually including angiotensin converting enzyme (ACE) inhibitors or angiotensin-receptor blockers (ARBs), calcium channel blockers, and or beta blockers, are frequently prescribed with a goal of normalizing blood pressure. Some clinicians also recommend statins to lower low density lipoprotein (LDL) cholesterol and antiplatelet agents, such as aspirin or clopidogrel, to reduce thrombosis. The current standard for revascularization in most patients is percutaneous transluminal angioplasty with stent placement across the stenosis. Angioplasty without stent placement is less commonly employed. Revascularization by surgical reconstruction is generally used only for patients with complicated renal artery anatomy or for patients who require pararenal aortic reconstructions for aortic aneurysms or severe aortoiliac occlusive disease.

The American College of Cardiology and the American Heart Association (ACC/AHA) recently published guidelines for the management of patients with peripheral arterial disease, including renal artery stenosis.8,9 These guidelines provide recommendations about which patients should be considered for revascularization; however, there remains considerable uncertainty on which intervention provides the best clinical outcomes. Among patients treated with medical therapy alone, there is the risk for deterioration of kidney function with worsening morbidity and mortality. Renal artery revascularization may provide immediate improvement in kidney function and blood pressure; however, as with all invasive interventions, it may result in mortality or substantial morbidity in a small percentage of patients.

Placement of renal artery stents can resolve dissections, minimize stenosis recoil and restenosis, and correct translesional pressure gradients. The evidence for durability of clinical benefit is unclear; the majority of published studies on stent placement in ARAS had followup duration of less than two years. Comparison among studies on the effect of revascularization on hypertension and kidney function is limited because of differences in medical therapy, target blood pressure, and criteria for improvement.4

Considerable controversy remains regarding optimal strategies for evaluation and management of patients with ARAS; the evidence supporting benefit of aggressive diagnosis and treatment remains unclear. There is uncertainty as to whether patients with anatomically amenable lesions truly benefit from invasive interventions when compared with medical treatment. Meanwhile, a Medicare claims analysis found that the rate of percutaneous renal artery revascularization has rapidly increased between 1996 and 2000 with the number of interventions increasing from 7,660 to 18,520.10 Data provided to the Tufts-New England Medical Center EPC by the Cordis Corporation of Medicare Provider Analysis and Review (MEDPAR) File for 2003 to 2005 may indicate a leveling off of the number of RAS lesions being treated with angioplasty and stent (summary data available from the Tufts-New England Medical Center EPC). According to their data, there were 15,339 stents placed in renal arteries in 2003, 17,544 in 2004, and 17,643 in 2005.

Scope and Key Questions

This section is reproduced verbatim from the original RAS Comparative Effectiveness Review.1

This report summarizes the evidence evaluating the effect and safety of angioplasty with stent placements and medical therapies in the treatment of ARAS, particularly after long-term followup. The key questions and principal definition of terms were determined with the assistance of a technical expert panel. Key questions updated in this report are:

  1. For patients with atherosclerotic renal artery stenosis in the modern management era (i.e., since JNC-5 in 1993††), what is the evidence on the effects of aggressive medical therapy (i.e., antihypertensive, antiplatelet, and antilipid treatment) compared to renal artery angioplasty with stent placement on long-term clinical outcomes (at least 6 months) including blood pressure control, preservation of kidney function, flash pulmonary edema, other cardiovascular events, and survival?
    • 1a. What are the patient characteristics, including etiology, predominant clinical presentation, and severity of stenosis, in the studies?
    • 1b. What adverse events and complications have been associated with aggressive medical therapy or renal artery angioplasty with stent placement?
  2. What clinical, imaging, laboratory and anatomic characteristics are associated with improved or worse outcomes when treating with either aggressive medical therapy alone or renal artery angioplasty with stent placement?
  3. What treatment variables are associated with improved or worse outcomes of renal artery angioplasty with stent placement, including periprocedural medications, type of stent, use of distal protection devices, or other adjunct techniques?

Analytic Framework

This section is reproduced verbatim from the original RAS Comparative Effectiveness Review.1

We applied the analytic framework depicted in Figure 1 to answer the key questions in the evaluation of the treatment modalities for ARAS. This framework addressed relevant clinical outcomes. It also examined clinical predictors that affected treatment outcomes. While evidence from high quality randomized controlled trials (RCTs) was preferred, these data were rare, so nonrandomized and uncontrolled studies were used to augment the evidence.

Figure 1

Figure 1

Analytic framework for evaluating the effectiveness and safety of treatments for renal artery stenosis

These data are graphically represented by Cordis at http://www​.cms.hhs.gov​/determinationprocess/downloads/id202​.pdf (accessed September 4, 2007) in their letter of March 27, 2007 to the Medicare Evidence Development & Coverage Advisory Committee.

5th Joint National Committee on Detection, Evaluation, and Treatment of High Blood Pressure (1993). These guidelines marked a substantial change from previous guidelines in treatment recommendations for hypertension, including more aggressive blood pressure targets. This time point also marks when ACE inhibitors began to be used more routinely for patients with severe hypertension.

Footnotes

These data are graphically represented by Cordis at http://www​.cms.hhs.gov​/determinationprocess/downloads/id202​.pdf (accessed September 4, 2007) in their letter of March 27, 2007 to the Medicare Evidence Development & Coverage Advisory Committee.

††

5th Joint National Committee on Detection, Evaluation, and Treatment of High Blood Pressure (1993). These guidelines marked a substantial change from previous guidelines in treatment recommendations for hypertension, including more aggressive blood pressure targets. This time point also marks when ACE inhibitors began to be used more routinely for patients with severe hypertension.

Cover of Comparative Effectiveness of Management Strategies for Renal Artery Stenosis: 2007 Update
Comparative Effectiveness of Management Strategies for Renal Artery Stenosis: 2007 Update [Internet].
Comparative Effectiveness Reviews, No. 5.
Balk E, Raman G.

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