For T2DM, the Quality of Guidelines on Oral Meds Varies Dramatically

Wendy L. Bennett, MD, MPH, from the Johns Hopkins University School of Medicine in Baltimore, Maryland, and colleagues wrote, "In March 2011, the Institute of Medicine (IOM) released the report Clinical Practice Guidelines We Can Trust in response to increasing international concerns about low-quality and highly variable guideline development processes." "Improvements have occurred over time, but reviews of guidelines continue to report deficiencies in the quality of guidelines, particularly in describing methods for identifying evidence, grading the strength of recommendations, and identifying guideline authors' conflicts of interest with industry. In addition, guidelines may give conflicting recommendations."

Since 1995, there have been 11 classes of medications introduced to treat patients with T2DM. The goals of this review were to determine whether guidelines on oral medications for T2DM are consistent with evidence from a peer-reviewed systematic review published in 2007, and whether guideline consistency is associated with the quality of guideline development.

The reviewers searched MEDLINE, CINAHL, and guideline-specific databases between July 2007 and August 2011, reflecting the time post publication of the 2007 peer-reviewed systematic review on oral diabetes medications. Inclusion criteria, assessed independently by 2 reviewers, were English-language guidelines on oral medications to treat T2DM that were implemented in the United States, United Kingdom, or Canada.

The reviewers determined whether the selected guidelines concurred with 7 evidence-based conclusions from the 2007 systematic review. Using 2 domains (rigor of development and editorial independence) from the Appraisal of Guidelines Research and Evaluation (AGREE) tool, 2 reviewers independently evaluated guideline quality based on 7 key elements of systematic review and reporting.

Although the search retrieved 1000 citations, screening identified only 11 guidelines meeting the inclusion criteria. Of these, 7 guidelines agreed that metformin is the preferred first-line agent, and 10 guidelines agreed that thiazolidinediones compared with other oral medications are linked to increased rates of edema and congestive heart failure.

One of the 11 guidelines addressed no evidence-based conclusions, and at the other extreme, 5 guidelines agreed with all 7 evidence-based conclusions. According to AGREE criteria, the overall quality of all of the guidelines was poor, particularly in use of systematic methods to identify evidence. Furthermore, most guidelines were susceptible to bias.

The guidelines varied greatly in domain summary scores for the rigor of development (median, 28.6%; range, 16.7% - 100.0%) and editorial independence (median, 75.0%; range, 8.3% - 100.0%). Higher-quality scores were associated with a greater number of recommendations consistent with the evidence-based conclusions.

Limitations of this systematic review include that it included only English-language guidelines addressing clinicians in the United States, the United Kingdom, and Canada, and that it included only recommendations regarding oral medications.

"Not all practice guidelines on oral treatment of type 2 diabetes were consistent with available evidence from a systematic review," the study authors write. "Guidelines judged to be of higher quality contained more recommendations consistent with evidence-based conclusions. The quality of guideline development processes varied substantially."

Following the new IOM definition of a guideline and guideline development standards should help to improve guideline quality, according to the authors.

Ann Intern Med. 2012;156:27-36.