Updating the OMERACT Filter: Core Areas as a Basis for Defining Core Outcome Sets

Case Studies and Breakout Discussions

Five illustrative case studies were reported, each to 2 breakout groups before a discussion among OMERACT 11 delegates. Case presenters addressed specific questions on their current work (Table 1A, B). Breakout discussion groups with about 20 participants, including 2 patient partners, were first asked to consider the match between the presented case study and the proposed core area framework, its illustration of the importance of contextual factors, and to list any elements of the framework the case study had not addressed. Subsequently the groups considered in more general terms how outcome measurement sets can be developed and addressed the question, “In the light of these considerations, do you think the proposed concepts of core areas and core domains with contextual factors offer a useful model for core domain set development?”

Report Back to Plenary and Discussion

Each breakout group reported the main points from its discussion to a plenary session of all participants. While the case studies each brought to light specific points related to particular areas of work (helpful for the OMERACT group working in that area to consider further), 20 common issues emerged requiring clarification and resolution. These themes and the broad areas where existing work was entirely compatible with the new proposal were further explored during a highly participative plenary discussion session and are summarized in Table 2.

Many participants had difficulty using death as an outcome in all circumstances. In many case studies, death was not a direct outcome of interest: it was not expected that any deaths would be related to the condition (e.g., hand osteoarthritis) or treatment (e.g., physiotherapy) or would occur in the time window under investigation (e.g., the short-term response to intramuscular glucocorticoids). Participants did recognize that any death occurring during a clinical trial would need to be reported regardless of perceived causality. Other participants raised the possibility that “states worse than death” may be experienced by patients and wondered how this would be dealt with within the framework.

The concept and importance of effect on life as a core area (including function, quality of life, the ICF domains¹¹, patient perception of health, etc.) was widely accepted. Debate centered on whether, at a core area level, life impact should be subdivided further. Several different suggestions were made, such as work-related problems, mobility and independence, and social interactions, but these were often relevant in only 1 disease group or 1 particular context. No clear consensus about further subdivisions of life impact emerged.

“Considering Resource Use as a Core Area” produced the greatest discussion. Many participants saw this as an economic evaluation that was worth undertaking only in studies designed for that purpose. Some felt that resources included family support, support at work to continue working, personal time and effort of the patient, opportunity costs to the healthcare system, etc. Other remarks addressed the costs/feasibility of adequately capturing resource use; and the early development phase of a therapy where true resource costs may not be relevant to the question (e.g., in proof-of-principle studies), or not even calculable (e.g., the final cost of the therapy might depend on technical manufacturing issues and market forces). In sum, this area, while very important and relevant in many circumstances, was felt to require additional discussion and delineation before it could be considered a definite core area.

The concept of pathophysiological manifestations also produced some debate as a core area. There was general recognition that some information concerning the underlying disease process and its activity was needed to measure the effects of any treatment, and that most of our existing outcome measures focused on evaluating this core area. For example, most of the current RA core set instruments (joint counts, acute-phase reactants, and imaging) measure a pathophysiologic manifestation of the underlying disease process. There was some confusion as to the way this area might be assessed — could symptoms of pain and swelling in a joint be used as a measure of pathophysiology? There was a feeling that this needs to be defined in a flexible way.

There was wide recognition of a strong conceptual need to consider contextual factors. Confounding factors, comorbidities, variation in healthcare systems, and factors related to psychological status were all identified as potential contextual factors. However, it was unclear to many participants how these factors would be identified and which would be labeled as “core” to particular investigations. A number of general issues emerged from the breakout group reports and the plenary discussion. A recurrent theme was the request to provide concrete examples for the theoretical framework. Whether adverse effects should be a core area was also a topic of disagreement and uncertainty. All agreed that adverse effects should be reported in trials, and it was recognized that this often constitutes a specific section within a clinical trial report. However, it was also agreed that any given adverse effect would occur under the umbrella of one of the proposed core areas.

There were many points raised in which issues related to choosing, testing, and developing specific instruments became entangled with questions of whether a core area or a particular core domain would be adequately addressed and hence whether a core set of outcome measures would then be achievable within the proposed framework. There was also a recognition that many existing instruments, such as questionnaires, relate to more than 1 core area, and participants were unclear whether this would allow separate assessment of different core areas.

Some participants were unsure of the difference between core areas, primary outcomes, and secondary outcomes, and wondered whether core areas were intended to be the primary or secondary outcome measures. They feared this might override the intention of trial designers in setting up the study protocol. There was also concern that the work of core outcome development might come to a halt if, in relation to a particular condition, a core domain was identified but no valid assessment instrument existed in that domain. This led to a fruitful exploration of the difference between core domains and core outcome sets, and a clearer understanding that there is a 2-step process in defining first core domains within the core areas, and second identifying (or devising) instruments to include in the core outcome set. Finally, and perhaps unsurprisingly, there was a strong call for inclusion of a review process to ensure that as data accumulate, the whole philosophy of the emerging Filter 2.0 framework would be regularly scrutinized and updated.

This OMERACT session was deliberately constructed to test the proposed Filter 2.0 framework of core areas, core domains and contextual factors, which had already been subject to discussion, debate, and extensive development before the meeting. Using case studies from different working groups allowed participants to probe the theoretical and practical implications of the framework, and to look for areas of strength and weakness. There was a broad agreement with the need to formalize an overarching structure to justify the subsequent selection of core domains. Until challenged by the introduction of the patient perspective and the emergence of the COMET initiative, the OMERACT community has, in effect, been relying on clinicians’ common understanding of the disease areas in which they are working. This workshop, which took place at the start of the OMERACT 11 conference, concluded from case studies and discussions that most of the current work of the OMERACT participants already fits into the principles of the new framework, but several important areas of uncertainty emerged, as described. If sufficient consensus was to be achieved in time for the plenary session at the end of the conference¹⁶, these areas would need to be clarified and addressed further by the Filter 2.0 development group.