Published Dec 2009
Rothman M, Burke L, Erickson P, et al. Use of existing patient-reported outcome (PRO) instruments and their modification: the ISPOR Good Research Practices for Evaluating and Documenting Content Validity for the Use of Existing Instruments and Their Modification PRO Task Force Report. Value Health. 2009;12(8):1075-1083.
Background: Patient-reported outcome (PRO) instruments are used to
evaluate the effect of medical products on how patients feel or function.
This article presents the results of an ISPOR task force convened to
address good clinical research practices for the use of existing or modified
PRO instruments to support medical product labeling claims. The focus of
the article is on content validity, with specific reference to existing or
modified PRO instruments, because of the importance of content validity
in selecting or modifying an existing PRO instrument and the lack of
consensus in the research community regarding best practices for establishing
and documenting this measurement property.
Methods: Topics addressed in the article include: definition and general
description of content validity; PRO concept identification as the important
first step in establishing content validity; instrument identification and
the initial review process; key issues in qualitative methodology; and
potential threats to content validity, with three case examples used to
illustrate types of threats and how they might be resolved. A table of steps
used to identify and evaluate an existing PRO instrument is provided, and
figures are used to illustrate the meaning of content validity in relationship
to instrument development and evaluation.
Results & Recommendations: Four important threats to content validity
are identified: unclear conceptual match between the PRO instrument
and the intended claim, lack of direct patient input into PRO item
content from the target population in which the claim is desired, no
evidence that the most relevant and important item content is contained
in the instrument, and lack of documentation to support modifications to
the PRO instrument. In some cases, careful review of the threats to
content validity in a specific application may be reduced through additional
well documented qualitative studies that specifically address the
issue of concern.
Conclusion: Published evidence of the content validity of a PRO instrument
for an intended application is often limited. Such evidence is,
however, important to evaluating the adequacy of a PRO instrument for
the intended application. This article provides an overview of key issues
involved in assessing and documenting content validity as it relates to
using existing instruments in the drug approval process.
Keywords: content validity, instruments, outcomes, patient-reported outcomes, validity.