Value in health : the journal of the International Society for Pharmacoeconomics and Outcomes Research
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This article focuses on the necessary psychometric properties of a patient-reported outcomes (PROs) measure. Topics include the importance of reliability and validity, psychometric approaches used to provide reliability and validity estimates, the kinds of evidence needed to indicate that a PRO has a sufficient level of reliability and validity, contexts that may affect psychometric properties, methods available to evaluate PRO instruments when the context varies, and types of reliability and validity testing that are appropriate during different phases of clinical trials. Points discussed include the perspective that the psychometric properties of reliability and validity are on a continuum in which the more evidence one has, the greater confidence there is in the value of the PRO data. ⋯ Psychometric testing ideally occurs before the initiation of Phase III trials. When testing does not occur prior to a Phase III trial, considerable risk is posed in relation to the ability to substantiate the use of the PRO data. Various qualitative (e.g., focus groups, behavioral coding, cognitive interviews) and quantitative approaches (e.g., differential item functioning testing) are useful in evaluating the reliability and validity of PRO instruments.
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This article deals with the incorporation of patient-reported outcomes (PROs) into clinical trials and focuses on issues associated with the interpretation and reporting of PRO data. The primary focus and context of this information relates to the evidentiary support and reporting for a labeling or advertising claim of a PRO benefit for a new or approved pharmaceutical product. ⋯ Clear specifications for considering a finding on a PRO measure, as clinically meaningful, need to be determined by instrument developers and psychometricians; they need to be reported for all clinical trials involving PRO end points. Clinical trial reports need to be comprehensive, clear, and sufficient to enable any reader to understand the methods, PRO measures, statistical analysis, and results.