Box 2.

Key stages in developing recommendations

• Methodological evaluation—Using defined criteria, evaluate the methodological quality of the evidence base for the guideline and give each study a quality rating according to a standard scale (below). The study type combined with the assessment of methodological quality determines the level of evidence
• Synthesis of evidence—Compile an evidence table of studies of an acceptable standard identified as relevant to each of the key clinical questions addressed by the guideline
• Considered judgment—Make a considered judgment about the relevance and applicability of the evidence to the target patient group for the guideline, the consistency of the evidence base, and the likely clinical impact of the intervention
• Grading system—Assign a grading to the recommendation according to the strength of the evidence base and the degree of extrapolation required to form the recommendation
• Quality rating for individual studies (adapted from Liddle et al⁴)
• ++ Applies if all or most criteria from the checklist are fulfilled; where criteria are not fulfilled, the conclusions of the study or review are thought very unlikely to alter.
• + Applies if some of the criteria from the checklist are fulfilled; where criteria are not fulfilled or are not adequately described, the conclusions of the study or review are thought unlikely to alter.
• − Applies if few or no criteria from the checklist are fulfilled; where criteria are not fulfilled or are not adequately described, the conclusions of the study or review are thought likely or very likely to alter.