Despite the increased use of stents to treat renal artery stenosis, there is little evidence to support revasculari-zation's superiority over medical management, according to a draft review by the Agency for Healthcare Research & Quality.

"While the theoretical benefits of revascularization are appealing, there is no robust evidence to allow individual patients and clinicians to decide which treatment option is best," the April 12 report states.

The draft report, "Comparative Effectiveness of Management Strategies for Renal Artery Stenosis," is part of AHRQ's Effective Health Care Program, initiated last year.

Renal artery stenosis, a narrowing of the renal artery usually caused by plaque build-up, often occurs in combination with hypertension and kidney disease.

Treatment options are medical management, including treatment with drug combinations that can result in side effects that may in fact speed kidney disease, and revascularization, which carries the risk of significant adverse events of its own.

AHRQ's review is intended to help patients and physicians make informed decisions about treatment options by summarizing available evidence on the safety and effectiveness of angioplasty with stenting compared with aggressive medical therapy.

The agency sought to learn what types of patients have been studied, what adverse events are associated with each treatment, and what factors contribute to better or worse outcomes.

AHRQ found through a literature search only two randomized, controlled studies that compared medical treatments to angioplasty, but neither entailed stent placement. The agency adds that "very limited evidence from direct comparisons suggests no difference in outcomes based on whether patients had stents placed or not."

Other published studies, including cohort studies and retrospective studies, are "fraught with numerous biases due to lack of randomization (among the large majority of these studies) and poor applicability" for determining the comparative effectiveness of the two treatment approaches, the report states.

AHRQ's analysis of the available evidence reveals no differences in kidney function outcomes, mortality rates or cardiovascular event rates between patients treated with angioplasty without stent placement and those who received medical treatment alone.

But angioplasty does appear to improve patients' blood pressure, particularly if the patient has bilateral, as opposed to unilateral, disease, AHRQ concludes.

Despite the dearth of evidence on the efficacy of the procedure, AHRQ notes that "as stent placement ha[s] become more common for atherosclerotic coronary and other arteries, stents have also been more commonly placed during renal artery angioplasty."

The ongoing Cardiovascular Outcomes in Renal Atherosclerotic Lesions (CORAL) trial should clear up some of the questions that AHRQ says remain unanswered.

The trial, initiated in 2004 and sponsored by the National Institutes of Health, will randomize 1,080 patients at 100 sites to either optimal medical therapy or medical therapy plus renal artery stenting. Results from the trial are expected in 2010 (¹ Also see "CORAL Renal Trial To Show Risks, Benefits Of Stenting Over Drugs" - Medtech Insight, 11 April, 2005., p. 20).

Patients enrolled in CORAL must have stenosis > 60% with a pressure gradient or stenosis > 80% without a gradient, and a history of hypertension refractory to two or more medications.

AHRQ notes "a potential risk...that the findings of the CORAL trial will be broadened to be considered applicable to patients" outside the study's population. "If angioplasty with stent is found to be of benefit in the CORAL trial, it is likely that the procedure will become more common also in patients with mild disease, even though there will not be evidence to support this," the report states.

AHRQ stresses that additional randomized, controlled trials are needed to address other populations, such as those with less severe stenosis or high-stage kidney disease.

Comments on the draft report are due May 10.

- Chloe Taft

Stenting Renal Arteries Sounds Good In Theory But Evidence Not There – AHRQ

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