IDSA Practice Guidelines Scrutinized for Evidence Level

Emma Hitt, PhD

January 10, 2011

January 10, 2011 — More than half of the current recommendations among the 41 current Infectious Diseases Society of America (IDSA) guidelines are based on evidence from expert opinion (level III) only; therefore, physicians should remain cautious when using these guidelines as their only source for making clinical decisions, a new report suggests.

Dong Heun Lee, MD, and Ole VIelemeyer, MD, from the Drexel University College of Medicine in Philadelphia, Pennsylvania, reported the results of their analysis in the January 10 issue of the Archives of Internal Medicine.

"In daily clinical work, practitioners sometimes assume that adhering to practice guidelines means practicing evidence-based medicine," the researchers write. "However, the quality of supporting literature can vary greatly."

A total of 4218 individual recommendations from 41 current IDSA guidelines, released between January 1994 and May 2010, were analyzed according to strength of recommendation and quality of supporting evidence. Although 43% (n = 1796) were considered strong (level A) recommendations, only 14% of these level A recommendations were supported by a strong quality of evidence (level I) such as randomized controlled trials. More than half were supported by expert opinions (level III) only.

The researchers noted that guidelines on surgical prophylaxis, travel medicine, and asymptomatic bacteriuria had the highest percentage of recommendations supported by level I evidence.

A comparison of 5 current IDSA guidelines that had recently been updated revealed a significant increase in the number of level I evidence recommendations in only 2 of the updated guidelines; most updated recommendations were supported by level II or level III evidence only.

The researchers listed difficulties of conducting large randomized controlled trials in the field of infectious diseases and the limitations of the IDSA evidence-grading system as 2 reasons for the limited number of recommendations supported by level I evidence.

The current IDSA guidelines "constitute a great and reliable source of information that should be used," the researchers conclude. However, in atypical cases they encourage "reviewing the primary literature and using one's clinical judgment rather than relying solely on recommendations."

To improve patient outcomes, the authors recommend more research in the form of well-designed and controlled clinical trials in areas where only low-level quality of evidence is available.

Guidelines Are A Starting Point, Not the Finish Line

John H. Powers, MD, from Scientific Applications International Corporation, Bethesda, Maryland, wrote an accompanying editorial, stating: "[G]uidelines may provide a starting point for searching for information, but they are not the finish line."

"Evaluating evidence is about assessing probability," Dr. Powers commented in a news release. "Perhaps the main point we should take from the studies on quality of evidence is to be wary of falling into the trap of 'cookbook medicine,' " Dr. Powers continues. "Although the evidence and recommendations in guidelines may change across time, providers will always have a need to know how to think about clinical problems, not just what to think."

The study was not commercially funded. The authors have disclosed no relevant financial relationships. Dr. Powers' work is supported by the National Cancer Institute and National Institute of Allergy and Infectious Disease, National Institutes of Health. He also reports receiving consulting fees from Acureon, Advanced Life Sciences, Astellas, AstraZeneca, Basilea, Centegen, Cerexa, Concert, Cubist, Destiny, Forest, Gilead, Great Lakes, Johnson & Johnson, LEO, Merck, Methylgene, MPEX, Pharming, Octoplus, Takeda, Theravance, and Wyeth.

Arch Intern Med. 2011;171:15-17, 18-22.