Updating the OMERACT Filter: Implications of Filter 2.0 to Select Outcome Instruments Through Assessment of “Truth”: Content, Face, and Construct Validity

• OMERACT
• OUTCOME AND PROCESS ASSESSMENT
• CONTENT VALIDITY
• RANDOMIZED CONTROLLED TRIALS
• CONSTRUCT VALIDITY
• FACE VALIDITY

The Outcomes in Rheumatology Clinical Trials (OMERACT) Filter provides guidelines for the development and validation of outcome measures for use in clinical research. Previous articles^1,2 described discussions on the proposed framework for defining Core Areas as the basis for the selection of Core Outcome Domains and hence appropriate Core Outcome Sets for clinical trials. The present article describes the discussion session on the later step of assessing each of the available instruments against the criteria for the “Truth” part of the OMERACT Filter³ (Figure 1). The OMERACT session on which the present article is based was deliberately constructed to test whether the new framework builds on OMERACT Filter 1.0 and to show how the selection of instruments and assessment of Truth would work in practice within the new Filter 2.0 framework. Using case studies from different actual OMERACT working groups, participants at the session reviewed ways in which instruments were selected and the Truth Criterion of Filter 1.0 was assessed and achieved.

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Figure 1.

Development of a core outcome measurement set from a core domain set. From Boers M, et al. J Clin Epidemiol 2014; in press; with permission.

A Core Outcome Measurement Instrument Set is defined as the minimum set of outcome measurement instruments that must be administered in each intervention study of a certain health condition within a specified setting to adequately cover a corresponding Core Domain Set. As depicted, the development process allows core set developers to declare a Preliminary Core Outcome Measurement Set when not all domains are covered by at least 1 applicable measurement instrument. The present article focuses on documenting the Truthful component of applicability (Figure 1).

The previous article¹ focused on the selection of the Core Domains. As can be seen in Figure 1, a literature search has been implemented and a list of candidate measurement instruments has been identified for each Domain and relevant subdomains within the 4 Core Areas (Death, Life impact, Resource use, Pathophysiological manifestations). Then, the clinimetric properties³ of these instruments are assessed (Figure 1 and Table 1) and 1 or more candidate instruments selected on the basis of their properties (truth, discrimination and feasibility). As Figure 1 shows, if no instrument identified in the literature search meets OMERACT criteria in a particular disease, a new instrument will need to be developed that meets these Filter criteria for Truth (and Discrimination and Feasibility as described elsewhere in this series⁴).

This OMERACT 11 session focused on the “Truth” part of the Filter, i.e. content, face, and construct validity.

The definitions for different types of validity encompassed within the Truth component (see Table 1) remain unchanged from Filter 1.0. However, different OMERACT groups have used various approaches to satisfy these criteria for the Truth requirement. This workshop was held to allow participants to present case studies representative of different methods used by different groups to satisfy these criteria.

A background discussion article² was prepared for this OMERACT 11 session. Further, the session sought to reassure participants that the new framework builds on OMERACT Filter 1.0 and to show how the selection of the instruments and assessment of Truth would work with the new Filter 2.0, using case studies drawn from Working Groups across the spectrum of OMERACT activities. Discussion (breakout) groups were invited to critically review how the case study might comply with or negate the new Filter 2.0 framework proposal, whether these observations had a more general application, and what issues remained to be resolved before consensus could be reached.

Further formal and informal discussions during the OMERACT 11 meeting provided opportunities for clarifications and resolution of many areas of uncertainty before a final plenary vote at the last conference session.