Abdur Rahman Khan, of the Division of Infectious Diseases in the Department of Medicine at King Fahd Medical City in Riyadh, Saudi Arabia, and colleagues assert in the latest issue of Clinical Infectious Diseases that there is an urgent need to support high quality research to strengthen the evidence available for the formulation of guidelines.
In their study, Khan, at al. (2010) sought to describe the distribution and temporal trends of the quality and strength of evidence supporting recommendations in the Infectious Diseases Society of America (IDSA)s clinical practice guidelines.
The researchers report that guidelines either issued or endorsed by IDSA from March 1994 to July 2009 were evaluated using the IDSA/US Public Health Service Grading System. In this system, the letters AE signify the strength of the recommendation, and numerals IIII indicate the quality of evidence supporting these recommendations. The distribution of the guideline recommendations among strength of recommendation and quality of evidence classes was quantified, and temporal changes between the first and current guideline version were evaluated.
Khan, et al. (2010) report that about one-half of the recommendations in the current guidelines are supported by level III evidence (derived from expert opinion). Evidence from observational studies (level II) supports 31 percent of recommendations, whereas evidence based on one randomized clinical trial (level I) constitutes 16 percent of the recommendations. The strength of recommendation was mainly distributed among classes A and B. Among guidelines with one revised version, the recommendations moved proportionately toward more level I evidence; consequently, there was a proportional increase in class A recommendations (+11.1 percent) with a decrease in class C recommendations (23.5 percent).
The researchers conclude that the IDSA guideline recommendations are primarily based on lowquality evidence derived from nonrandomized studies or expert opinion, and add that these findings highlight the limitations of current clinical infectious diseases research that can provide highquality evidence.
Reference: Khan AR, Khan S, Zimmerman V, Baddour LM and Tleyjeh IM. Quality and Strength of Evidence of the Infectious Diseases Society of America Clinical Practice Guidelines. Clinical Infectious Diseases 2010;51:1147-1156.