Optimal medication adherence is crucial for improved clinical and health outcomes. Medication adherence is defined as “the process by which patients take their medications as prescribed”. For rheumatic diseases, however, up to 85% of the patients do not fully adhere to their medication regimen.

The Outcome Measures in Rheumatology Adherence Working Group (OMERACT-Adherence Group) is currently developing a core domain set for trials of medication adherence interventions in patients with rheumatic diseases. The group consists of patients, healthcare professionals, researchers and other stakeholders. Their activities comprise: (1) a systematic literature review of outcome domains in medication adherence intervention trials in rheumatology, (2) interviews with patients and caregivers to identify their views on core domains, (3) nominal group technique with patients and caregivers to prioritise outcome domains, (4) an international modified Delphi study to define a preliminary core domain set, and (5) a consensus workshop to finalise a core domain set.