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GRADE guidelines: 8. Rating the quality of evidence-indirectness.

Overview
Title:
GRADE guidelines: 8. Rating the quality of evidence-indirectness.
Authors:
Guyatt GH, Oxman AD, Kunz R, Woodcock J, Brozek J, Helfand M, Alonso-Coello P, Falck-Ytter Y, Jaeschke R, Vist G, Akl EA, Post PN, Norris S, Meerpohl J, Shukla VK, Nasser M, Schünemann HJ, The GRADE Working Group
Journal:
J Clin Epidemiol.
Publication date:
2011 Jul 29
Volume:
Epub ahead of print
Link to pubmed:
http://www.ncbi.nlm.nih.gov/pubmed/21802903
Publication type:
Journal
Abstract
Direct evidence comes from research that directly compares the interventions in which we are interested when applied to the populations in which we are interested and measures outcomes important to patients. Evidence can be indirect in one of four ways. First, patients may differ from those of interest (the term applicability is often used for this form of indirectness). Secondly, the intervention tested may differ from the intervention of interest. Decisions regarding indirectness of patients and interventions depend on an understanding of whether biological or social factors are sufficiently different that one might expect substantial differences in the magnitude of effect. Thirdly, outcomes may differ from those of primary interest-for instance, surrogate outcomes that are not themselves important, but measured in the presumption that changes in the surrogate reflect changes in an outcome important to patients. A fourth type of indirectness, conceptually different from the first three, occurs when clinicians must choose between interventions that have not been tested in head-to-head comparisons. Making comparisons between treatments under these circumstances requires specific statistical methods and will be rated down in quality one or two levels depending on the extent of differences between the patient populations, co-interventions, measurements of the outcome, and the methods of the trials of the candidate interventions.
Preview

GRADE guidelines: 8. Rating the quality of evidence-indirectness. Guyatt GH, Oxman AD, Kunz R, Woodcock J, Brozek J, Helfand M et al. J Clin Epidemiol. 2011 Jul 29; Epub ahead of print:.

Page last updated: Oct 13, 2011
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