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Stricter standards needed for guidelines on oral diabetes treatments
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The quality of guidelines on oral medications for type 2 diabetes runs the gamut from high to low, according to a systematic review, with several guidelines showing inconsistencies with currently available evidence.
In 2007, researchers from the Johns Hopkins University Evidence-based Practice Center conducted a comparative effectiveness review of oral medications for adults with type 2 diabetes. Wendy L. Bennett, MD, MPH, assistant professor of medicine in the division of general internal medicine at the Johns Hopkins University School of Medicine, and colleagues then conducted a systematic review of guidelines published between 2007 and 2011 with recommendations on oral diabetes medications to determine whether guidelines agreed with seven evidence-based conclusions from the comparative effectiveness review.
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“We wanted to assess whether guidelines were evidence-based and rate their quality,” Bennett told Endocrine Today. “We also thought that understanding how guideline developers used evidence reviews could help inform the methods and topics for future comparative effectiveness reviews to make them applicable and translatable.”
Evaluating the evidence base
After searching Medline, Cinahl and guideline-specific databases, the researchers identified 11 guidelines from various organizations and institutions that met the inclusion criteria.
According to results, seven guidelines agreed with the conclusion from the 2007 review citing metformin as the preferred first-line agent. Additionally, 10 guidelines agreed with the conclusion that thiazolidinediones are associated with higher rates of edema and congestive heart failure when compared with other oral medications for diabetes. Eight guidelines recognized concerns about increased risk for ischemic heart disease with rosiglitazone (Avandia, GlaxoSmithKline) that were addressed in the 2007 review.
The researchers also noted that one guideline addressed none of the conclusions, whereas five agreed with all seven conclusions.
Variations in quality
The researchers evaluated guidelines’ quality using the seven-item rigor of development domain of the Appraisal of Guidelines for Research and Evaluation (AGREE) instrument, which assessed the following:
- Methods used to search for the evidence upon which the guidelines were based.
- Criteria for selecting the evidence.
- Methods used for formulating recommendations.
- Consideration of benefits, side effects and risks.
- An explicit link between the recommendations and supporting evidence.
- External review by experts outside the guideline-developing organization.
The researchers found significant variation among the guidelines, with summary scores for the rigor of development ranging from 16.7% to 100%, with a median of 28.6%. To measure risk for bias, they also evaluated the editorial independence domain from AGREE. Similarly, summary scores for this domain ranged from 8.3% to 100%, with a median of 75%.
Guidelines with higher quality scores tended to include more recommendations in keeping with the evidence-based conclusions from the 2007 review, according to the researchers.
Future implications
Although the researchers found significant differences among the guidelines, Bennett said they identified guidelines with high scores for quality that also incorporated recommendations consistent with the 2007 review.
“These guidelines tended to have rigorous guideline development methods involving systematic literature reviews of the evidence and rated the strength of their recommendations based on the evidence available,” she said. “They also had low risk for bias, such as conflicts of interest with pharmaceutical companies.”
However, Bennett said several guidelines still fell short. She highlighted the need for guideline developers to improve rigor and quality to meet standards set forth in the Institute of Medicine’s report, “Clinical Practice Guidelines We Can Trust.” Further, she added that the quality of these guidelines has ramifications outside the realm of clinical practice.
“Our findings also have implications for policymakers and health care organizations who are increasingly turning to published clinical practice guidelines to improve the quality and efficiency of health care, as well as to evaluate performance,” she said. “Understanding the limitations of guidelines, as well as the areas for improvement that we highlighted in this study, will inform health policy decisions around diabetes care.”
For more information:
Disclosure: Dr. Bennett and colleagues report no relevant financial disclosures.
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Clinical practice guidelines are meant to be decision-making aids for practitioners and their patients. During the past 20 years, the state-of-the-art for guideline development has evolved from primarily confluence of expert opinion to evidence-based recommendations, usually identifying the strength of the recommendations as a function of the volume and quality of evidence. Bennett and colleagues have done the diabetes community a great service by identifying over 1,000 “clinical practice guidelines” for care of diabetes mellitus, and then by culling them down to a mere 11 meeting their rigorous qualifying criteria of scholarship, recommendations and editorial review. I suspect that most Endocrine Today readers consult the American Diabetes Association/European Association for the Study of Diabetes and American Association of Clinical Endocrinologists clinical practice guidelines most often, and will be pleased to know that each of these clinical practice guidelines made the final cut for rigorous analysis. Each of these clinical practice guidelines scored respectably well with regard to the extent to which recommendations were consistent with available evidence and the degree of freedom of the guidelines development team from financial and other editorial control by a sponsoring organization. From a clinical standpoint, the highlights of the Bennett review are that the majority of high-quality clinical practice guidelines endorse metformin as the drug of choice for first-line treatment of type 2 diabetes mellitus, and the majority identify cardiovascular disease risk and congestive heart failure as risks of thiazolidinedione therapy. Most but not all clinical practice guidelines identified equivalent efficacy of the various oral antihyperglycemic agents and noninsulin injectables with regard to impact on HbA1c.
– Stephen A. Brietzke, MD
Endocrine
Today Editorial Board member
Disclosure: Dr. Brietzke reports no relevant financial disclosures.
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