Evaluation of guideline recommendations on oral medications for type 2 diabetes mellitus: a systematic review.

BACKGROUND Clinical practice guidelines have an important role in guiding choices among the numerous medications available to treat type 2 diabetes mellitus, but little is known about their quality. PURPOSE To assess whether guidelines on oral medications for type 2 diabetes are consistent with a systematic review of the current evidence and whether the consistency of the guidelines depends on the quality of guideline development. DATA SOURCES MEDLINE, CINAHL, and guideline-specific databases were searched between July 2007 and August 2011, after the 2007 publication of a peer-reviewed systematic review on oral diabetes medications. STUDY SELECTION Two reviewers independently screened citations to identify English-language guidelines on oral medications to treat type 2 diabetes that were applied in the United States, United Kingdom, and Canada. DATA EXTRACTION Reviewers assessed whether the guidelines addressed and agreed with 7 evidence-based conclusions from the 2007 systematic review. Two reviewers independently rated guideline quality by using 2 domains from the Appraisal of Guidelines Research and Evaluation instrument. DATA SYNTHESIS Of the 1000 screened citations, 11 guidelines met the inclusion criteria. Seven guidelines agreed with the conclusion that metformin is favored as the first-line agent. Ten guidelines agreed that thiazolidinediones are associated with higher rates of edema and congestive heart failure compared with other oral medications to treat type 2 diabetes. One guideline addressed no evidence-based conclusions, and 5 guidelines agreed with all 7 conclusions. The summary scores of the rigor of development (median, 28.6% [range, 16.7% to 100.0%]) and editorial independence (median, 75.0% [range, 8.3% to 100.0%]) domains varied greatly across guidelines. Guidelines that received higher quality scores contained more recommendations that were consistent with the evidence-based conclusions. LIMITATION Only English-language guidelines targeting users in the United States, United Kingdom, and Canada that contained recommendations on oral medications were included. CONCLUSION Not all practice guidelines on oral treatment of type 2 diabetes were consistent with available evidence from a systematic review. Guidelines judged to be of higher quality contained more recommendations consistent with evidence-based conclusions. The quality of guideline development processes varied substantially. PRIMARY FUNDING SOURCE Agency for Healthcare Research and Quality.