A study in the February 25 issue of JAMA reports that evaluation of clinical practice procedure for treating cardiovascular disease finds that present recommendations mainly rely on inferior levels of evidence or expert opinion.

According to background data in the article, practitioners base their decision for suitable heath care for particular patients' circumstances on clinical practice guidelines which are frequently considered as standard of evidence-based medicine.

Clinical practice guidelines have been released to offer recommendations on how to care for cardiovascular disease patients by the American College of Cardiology (ACC) and the American Heart Association (AHA), for more than two decades. Degree of evidence and class of recommendations are the basis for the grading system presently used by the ACC/AHA guidelines. The combination of an objective description of evidence and the types of studies sustaining the recommendation and expert opinion is used for the classification of level of evidence, and categorized as A (higher level of evidence), B, or C (lower level of evidence).

The level of recommendation is indicated by class of recommendation. It involves an opinion of the guideline writers on the comparative strengths and weaknesses of the study information, as well as an evaluation of the relative consequence of the risks and benefits identified by the evidence. The classes are ranked as I (evidence that a treatment or procedure is effective), II, IIa, IIb and III (evidence that a treatment or procedure is not effective).

It is unknown if the rise in cardiovascular disease studies increases the certainty of guideline recommendations and supporting evidence. The changes in recommendations in ACC/AHA cardiovascular guidelines and the evaluation of the adequacy of the evidence used for present guideline recommendations were studied by Pierluigi Tricoci, M.D., M.H.S., Ph.D., Duke University, Durham, N.C. and team. Information from ACC/AHA practice guidelines issued from 1984 to September 2008 was used in the study. A total of 7,196 recommendations and fifty-three guidelines on twenty-two topics were analyzed.

The total number of recommendations had a 48 percent increase (1,330 to 1,973), from the earliest guideline to the present version, taking into account only the current guidelines with at least one review. In general, there was a shift to class II recommendations, a drop in class II recommendations, while the use of class I remained invariable. In a total of 2,711 recommendations, in the sixteen present guidelines reporting levels of evidence, 11 percent (314) of the recommendations were classified as level of evidence A, and 48 percent (1,246) as level of evidence C.

In the total of 1,305 class I recommendations of guidelines reporting evidence, only 19 percent (245) have a level of evidence A, 36 percent (481) have a level of evidence C. In the different categories of guidelines (disease, intervention, or diagnosis) and the different individual guidelines, the level of evidence considerably varies.

In conclusion, the authors write: "Our finding that a large proportion of recommendations in ACC/AHA guidelines are based on lower levels of evidence or expert opinion highlights deficiencies in the sources of definitive data available for the generation of cardiovascular guidelines. To remedy this problem, the medical research community needs to streamline clinical trials, focus on areas of deficient evidence, and expand funding for clinical research. In addition, the process of developing guidelines needs to be improved with information about the impact that recommendations based on lower levels of evidence has on clinical practice. Finally, clinicians need to exercise caution when considering recommendations not supported by solid evidence."

JAMA. 2009; 301[8]:831-841

Editor's Note: Please see the article for additional information, including other authors, author contributions and affiliations, financial disclosures, funding and support, etc.

Editorial: Re-evaluation of Clinical Practice Guidelines

Terrence M. Shaneyfelt, M.D., M.P.H., and Robert M. Centor, M.D., University of Alabama School of Medicine, Birmingham, in a complementary editorial, note that there is a need for important changes in clinical practice guidelines if they are to be maintained.

"However, it seems unlikely that substantial change will occur because many guideline developers seem set in their ways. If all that can be produced are biased, minimally applicable consensus statements, perhaps guidelines should be avoided completely. Unless there is evidence of appropriate changes in the guideline process, clinicians and policy makers must reject calls for adherence to guidelines. Physicians would be better off making clinical decisions based on valid primary data."

JAMA. 2009 ;301[8]:868-869.

Stephanie Brunner (B.A.)