Achieving consensus on minimum data items (including core outcome domains) for a longitudinal observational cohort study in rheumatoid arthritis

Objectives: To obtain consensus on minimum data items for an observational cohort study in rheumatoid arthritis (RA) in the UK and to make available the process for similar studies and other rheumatic conditions. Methods: Individuals with a diverse range of expertise and backgrounds were invited to participate in a process to propose a minimal core dataset (MCD) for research studies, commissioned by Arthritis Research UK as part of the larger INBANK project. The group included patients and representatives from clinical and academic rheumatology, outcomes science, stratified medicine, health economics, national professional and academic bodies/ committees. A process was devised based on Outcome Measures in Rheumatology Clinical Trials (OMERACT) principles to review aims/objectives, definition of scope, identification of important research questions, and selection of key domains. Results: Following the initial multi-stakeholder meeting, subsequent teleconferences and email communications, consensus was obtained on: 1. Most important and relevant research questions; 2. Agreement on how the OMERACT Core Areas (life impact, pathophysiological manifestations, resource use and death) could form the basis of a MCD; 3. Consensus on 22 items for inclusion into a MCD. Workshops were undertaken for two essential items which required further exploration: work/social participation and co-morbidity. Conclusions: Consensus for proposed minimal data items for long-term observational cohort studies of RA in the UK posed novel challenges and opportunities, and was largely successful. Further work is needed to select instruments for two important items and to achieve compatibility with other UK national initiatives, and more widely across Europe.