Lacking Quality Evidence

Review of practice guidelines shows that many recommendations lack strong evidence

/ Author:  / Reviewed by: Joseph V. Madia, MD

(RxWiki News) Health care professionals base much of their work on practice guidelines issued by experts. New research shows that this might be problematic.

According to an article that appears in the January 10 issue of Archives of Internal Medicine, over half of the recommendations included in practice guidelines for infectious disease specialists lack strong evidence. In fact, many of the recommendations are based on opinion.

As the authors note, clinical practice guidelines have both helped and hindered the clinical decision-making process. Many recommendations have helped assess and streamline health care delivery in addition to educating professionals and the public. However, the sheer quantity of recommendations has overloaded and cramped the process as well.

Dong Heun Lee, M.D., and Ole Vielemeyer, M.D., of Drexel University College of Medicine in Philadelphia set out to assess the strength of 41 guidelines issued by the Infectious Diseases Society of America (IDSA). They classified the strength of the guideline recommendations in categories A through C, an A signifying good evidence, a B signifying moderate evidence, and a C signifying poor evidence. In addition to A through C categories, the researchers classified some recommendations with D and E.

Looking at IDSA guidelines released between January 1994 and May 2010, the researchers also evaluated the quality of the evidence supporting the recommendations. They classified quality of evidence in levels I through III. A level I indicates that evidence came from at least one randomized controlled trial. Level II evidence came from at least one non-randomized, well designed clinical trial. A level III indicates that evidence came from experience-based opinions of experts, descriptive studies, or reports of expert committees.

Included in the 41 guidelines assessed by Lee and Vielemeyer were 4,218 individual recommendations. The researchers ranked 14 percent of the recommendations as supported by level I evidence, 31 percent as level II, and 55 percent as level III. Twenty-three percent of recommendations in the A category were backed by level I evidence while another 37 percent were back by level III evidence.

The author's point out that the lack of randomized control trials in the field of infectious diseases may be due to factors other than careless science. They say that certain trials may be deemed unfeasible or even unethical. However, they conclude that future research should focus on building high-quality evidence so that physicians and policy makers can have stronger recommendations by which to make decisions.

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Review Date: 
January 11, 2011
Last Updated:
August 18, 2011