Introduction: Over the years, Outcome Measures in Rheumatology Clinical Trials (OMERACT) has worked toward consensus on core sets for outcome measurement in specific rheumatologic diseases. OMERACT core sets refer to the minimum number of domains and instruments essential to address the desired outcomes in trials. "Domains" are the attributes of an activity or function. This article discusses the need for an open process for selecting domains, existing frameworks for choosing domains, and the importance of describing the methods for selecting domains.
Methods: We reviewed the domains selection process of 3 OMERACT groups working on patient-reported outcomes (PRO). We categorized these methods in a hierarchy of comprehensiveness and examined the extent to which they address related issues.
Results: There was agreement that a gold standard for domain selection would include 3 important aspects: following a framework, remaining true to the clinical question, and including the clinically relevant outcomes for both benefits and harms.
Discussion: OMERACT participants agreed that a guide for the options for developing domains that meet the OMERACT Filter would be useful. More discussion and explanation is needed to outline outcomes related to the patient perspective that are not covered by the current version of the International Classification of Functioning, Disability and Health (ICF) and to explain the usefulness of the population/intervention/comparison/outcome (PICO) structure in domain selection. Future OMERACT work includes addressing these issues and developing a framework based on the ICF to support comprehensive outcome measurements.