Biological and social factors, such as age, comorbidities and the care system, may - as well-established effect-modifiers - limit the transferability of study results to populations with dissimilar characteristics. In order to enable transparent and evidence-based decisions in systematic reviews and guidelines targeting subpopulations that are little or not represented in the study landscape, the GRADE approach is a valid tool to assess the certainty of the evidence. GRADE provides a structured methodology that covers all steps, from developing a precise question, prioritizing patient-relevant outcomes and assessing the available evidence to derive recommendations for practice, among other things. Evaluating confidence in a body of evidence comprises judgments on risk of bias, study heterogeneity, directness, including comparability between study population and target population, precision of effect estimates and publication bias. Because GRADE demands transparent decisions about the applicability of study results from the study population to the target population, gaps in the evidence landscape can be uncovered. Overall, the approach cannot solve the problem of the transferability of study results. It does, however, support the explicit handling of applicability and can give impetus to targeted research gaps.
Keywords: GRADE; Indirektheit; Qualitätsbewertung; indirectness; quality appraisal; transferability; Übertragbarkeit.
Copyright © 2019. Published by Elsevier GmbH.