Background: Clinical practice guidelines (CPGs) can be helpful in distilling the medical research literature for clinicians; however, the guidelines should acknowledge the variable methodological quality used in clinical research by tempering their recommendations with a 'levels of evidence' scale.
Objective: To evaluate the proportion of English-language cardiovascular CPGs that provide the user with recommendations graded according to a defined levels of evidence scale. In addition, to evaluate other key aspects important in the critical appraisal of CPGs.
Methods: CPGs for atrial fibrillation, congestive heart failure and myocardial infarction were identified by searching MEDLINE, a reference text of CPGs and the Internet. Each CPG was evaluated using a priori-defined criteria based on the Evidence-Based Medicine Working Group's paper on critical appraisal of CPGs, including use of a reproducible search strategy, method of obtaining consensus, peer review and testing in practice.
Results: A total of 95 CPGs were evaluated. Only 13% graded their recommendations using a defined levels of evidence scale. In addition, few CPGs documented a reproducible search strategy or peer review process, and none had been formally tested in practice.
Conclusions: Reporting the levels of evidence for recommendations is an important component of CPGs, yet this system is not widely used.