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Canadian Pharmacists Association
Canadian Pharmacists Association
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Chapter 2: Methods

Canadian Diabetes Association 2013 Clinical Practice Guidelines

Process
  • The CDA CPGs were developed by a group of 120 volunteers, including health professionals from a wide range of specialties and people with diabetes.
  • The following principles were adopted for each recommendation in the CPGs:
    • Each recommendation had to address a clinically important question related to 1 or more of the following: detection, prognosis, prevention or management of  diabetes and its sequelae. Health benefits, risks and side effects of interventions were considered in formulating the recommendations. Patient preferences and values were sought from expert panel members with diabetes and literature (where available).
    • Whenever possible, each recommendation had to be justified by the strongest clinically relevant empirical evidence. The strength of this evidence had to be noted.
    • Each recommendation had to be assigned a grade based on the available evidence, its methodological strength and its applicability to the Canadian population.
    • Each recommendation had to be approved by the Steering Committee and Executive Committee, with 100% consensus.
    • Harmonization was sought with other Canadian guideline bodies, including the Canadian Cardiovascular Society (CCS), the Canadian Hypertension Education Program (CHEP), the Canadian Cardiovascular Harmonization of National Guidelines Endeavour (C-CHANGE) and the Society of Obstetricians and Gynecologists of Canada (SOGC).
Identifying and Appraising the Evidence
  • Authors were asked to explicitly define A) the population to which a guideline would apply; B) the test, risk factor or intervention being addressed; C) the “gold standard” test or relevant intervention to which the test or intervention in question was compared; and D) the clinically relevant outcomes being targeted.
  • Each citation that was used to formulate or revise a recommendation was assigned a level of evidence according to prespecified criteria, reflecting the methodological quality of the paper.
  • Because they could not be critically appraised, meeting abstracts, narrative review articles, news reports and other sources could not be used to support recommendations. Papers evaluating the cost effectiveness of therapies or diagnostic tests were also not included.

TABLE 1

Guideline Development
  • In the absence of new evidence since the publication of the 2008 CPGs, recommendations from the 2008 document were not changed.
  • The final grading assigned to each recommendation depended on the overall evidence available, including the relative strengths of the studies from a methodological perspective and the studies' findings.
Grading the Recommendations

TABLE 2

  • After formulating new recommendations or modifying existing ones based on new evidence, each recommendation was assigned a grade from A through D.
  • The highest possible grade that a recommendation could have was based on the strength of evidence that supported the recommendation (i.e., the highest level of evidence assigned to studies on which the recommendation was based).
  • The assigned grading was lowered in some cases, e.g., if the evidence was not applicable to Canadians, if the findings from relevant (and equally rigorous) studies on the topic were conflicting, if certain subgroups were not well represented in the study or the beneficial effect of an intervention was less clear, etc.
  • In the absence of Level 1, 2 or 3 supporting evidence, or if the recommendation was based on the consensus of the Steering and Executive Committees, the highest grade that could be assigned was D.
Interpreting the Assigned Grade of a Recommendation
  • The grade assigned to each recommendation is closely linked to the methodological rigour and robustness of the relevant clinical research. A high grade reflects a high degree of confidence that following the recommendation will lead to the desired outcome.
  • A lower grade reflects weaker evidence and a greater possibility that the recommendation will change when more evidence is generated in the future.
External Peer Review and Independent Methodological Review
  • A draft document was circulated nationally and internationally for review by numerous stakeholders and experts in relevant fields. Subsequently, a separate panel of 6 methodologists independently reviewed each recommendation, its assigned grade and supportive citations.
Disclosure of Duality of Interest
  • Committee members were volunteers and received no remuneration or honoraria for their participation.
  • Members of all committees signed an annual duality of interest form listing all financial interests or relationships with manufacturers of commercial products and/or providers of commercial services.
  • Funding for the development of the guidelines was provided from the general funds of the Canadian Diabetes Association and from unrestricted educational grants from Novo Nordisk Canada Inc, Eli Lilly Canada Inc, Merck Canada Inc, Bristol-Myers Squibb and AstraZeneca, and Novartis Pharmaceuticals Canada Inc. These companies were not involved in any aspect of guideline development, literature interpretation or publication. They also did not have access to guideline meetings, guideline drafts or committee deliberations.
Guideline Updates
  • A process to update the full guidelines will commence within 5 years and will be published in 2018.
  • Updates to individual chapters may be published sooner in the event of significant changes in evidence supporting the recommendations.

Table 1: Criteria for assigning levels of evidence to the published studies
Level Criteria
Studies of diagnosis
Level 1 a.   Independent interpretation of test results (without knowledge of the result of the diagnostic or gold standard)
b.   Independent interpretation of the diagnostic standard (without knowledge of the test result)
c.   Selection of people suspected (but not known) to have the disorder
d.   Reproducible description of both the test and diagnostic standard
e.   At least 50 patients with and 50 patients without the disorder
Level 2 Meets 4 of the Level 1 criteria
Level 3 Meets 3 of the Level 1 criteria
Level 4 Meets 1 or 2 of the Level 1 criteria
Studies of treatment and prevention
Level 1A a.   Comprehensive search for evidence
b.   Authors avoided bias in selecting articles for inclusion
c.   Authors assessed each article for validity
d.   Reports clear conclusions that are supported by the data and appropriate analyses

OR
Appropriately designed RCT with adequate power to answer the question posed by the investigators

a.   Patients were randomly allocated to treatment groups
b.   Follow-up at least 80% complete
c.   Patients and investigators were blinded to the treatment ∗
d.   Patients were analyzed in the treatment groups to which they were assigned
e.   The sample size was large enough to detect the outcome of interest
Level 1B Nonrandomized clinical trial or cohort study with indisputable results
Level 2 RCT or systematic overview that does not meet Level 1 criteria
Level 3 Nonrandomized clinical trial or cohort study; systematic overview or meta-analysis of level 3 studies
Level 4 Other
Studies of prognosis
Level 1 a.   Inception cohort of patients with the condition of interest but free of the outcome of interest
b.   Reproducible inclusion/exclusion criteria
c.   Follow-up of at least 80% of subjects
d.   Statistical adjustment for extraneous prognostic factors (confounders)
e.   Reproducible description of outcome measures
Level 2 Meets criterion a) above, plus 3 of the other 4 criteria
Level 3 Meets criterion a) above, plus 2 of the other criteria
Level 4 Meets criterion a) above, plus 1 of the other criteria
RCT, randomized, controlled trial.
* In cases where such blinding was not possible or was impractical (e.g. intensive vs. conventional insulin therapy), the blinding of individulas who assessed and adjudicated study outcomes was felt to be sufficient.
Table 2: Criteria for assigning grades of recommendations for clinical practice
Grade Criteria
Grade A The best evidence was at Level 1
Grade B The best evidence was at Level 2
Grade C The best evidence was at Level 3
Grade D The best evidence was at Level 4 or consensus

If you would like more details on this topic, including references, please visit the Canadian Diabetes Association Clinical Practice Guidelines: Chapter 2.