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Half of cardiac guidelines are not evidence based.

Nearly half of current clinical practice recommendations from the American College of Cardiology and the American Heart Association are based on expert opinion, case studies, or standards of care, and hence are not evidence based.

This may or may not be a problem, but it highlights the need for more studies to produce data that would fully substantiate how cardiovascular disease should be managed.

The American College of Cardiology and the American Heart Association "fully support the idea that as much as possible, we should have an evidence base, but there are many clinical situations where the studies have just not been done," said Dr. Sidney C. Smith Jr., professor of medicine and director of the center for cardiovascular science and medicine at the University of North Carolina at Chapel Hill. And in some cases it does not make sense to test standard practice in a controlled study, such as running an ECG on patients with chest pain, he noted.

Dr. Smith disagreed with the idea of producing practice guidelines only when backed up by study results. "There are situations when providers, patients, and payers need recommendations. It's important that we get the best opinion possible and indicate that it is expert opinion and not based on the results of a randomized, controlled trial. ... We've made tremendous progress in the past decade to develop recommendations based on evidence, but we have much more work to do," said Dr. Smith, who is also a former chief science officer for the AHA and currently chairs the ACC /AHA Task Force on Practice Guidelines.

Dr. Smith was coauthor of a recent study of the evidence behind all 2,711 practice recommendations in the 16 current guidelines promoted by the ACC and AHA joint program (JAMA 2009; 301:831-41). Of these recommendations, 11% were backed by level A evidence (multiple randomized trials or meta-analyses), 39% by level B evidence (a single randomized trial, or nonrandomized studies), and 48% by level C evidence (expert opinion, case studies, or standards of care). (The total is less than 100% because of rounding.)

Some experts who deal with crafting clinical practice guidelines take a dim view of basing them on level C evidence.

"Expert opinion is quite misleading" when used as the basis for a practice recommendation, said Dr. Diana B. Petitti, professor of biomedical informatics at Arizona State University in Phoenix and vice chair of the U.S. Preventive Services Task Force (USPSTF).

"Expert opinions imply that there is something that the experts know that the clinician doesn't know. I don't think it's always appreciated that it's only opinion," she said. "There is a tendency to make guidelines and recommendations seem authoritative. 1 believe that physicians think that there is a great deal more behind authoritative recommendations than there might be when you lift the lid of the box and see what's underneath."

Dr. Petitti prefers the USPSTF approach, which labels opinion-based statements to avoid categorizing them as recommendations. When study results are lacking, she noted, the USPSTF often uses a "chain of evidence" process to build a "plausible pathway" from existing evidence. In the absence of direct evidence that weight loss prevents cardiovascular disease, for example, the USPSTF would focus on evidence supporting the broader premise that weight loss has proven benefits, such as improvement of hypertension and serum lipids.

She also finds fault with the involvement of experts with conflicts of interest--a problem that the ACC and AHA attempt to resolve by full disclosure of all potential conflicts. "People are naive about their ability to make unbiased judgments in the face of personal financial or intellectual interests," said Dr. Petitti, who said she prefers to completely bar people with a conflicting interest in a recommendation from voting.

Even supporters of the ACC/AHA program acknowledge that recommendations based on expert opinion are not ideal. "Expert opinion is still evidence--it's just a weaker quality of evidence," said Dr. Robert A. Harrington, an interventional cardiologist and professor of medicine at Duke University in Durham, N.C., who chairs the ACC/AHA task force that develops consensus documents (practice statements for topics where the level of evidence is so limited that formal recommendations are not possible).

A new charge to the ACC/AHA committees that produce practice recommendations is to identify areas that need more study and funding, Dr. Smith said.

Another approach is to better integrate research goals into clinical practice. "Right now, research mostly runs in parallel to routine practice, rather than integrated into it," Dr. Harrington said in an interview. A recent report from the National Heart, Lung, and Blood Institute (that Dr. Harrington helped write) called for better leveraging of cardiovascular research resources and the efforts of physicians, patients, industry, and government agencies. He hopes that Health and Human Services agencies will push for more research in the context of routine practice.
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Author:Zoler, Mitchel L.
Publication:Internal Medicine News
Geographic Code:1USA
Date:Apr 1, 2009
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