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

Objectives. To obtain consensus on the minimum data items for an observational cohort study in 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 of proposing a minimum 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, and national professional and academic bodies/committees. A process was devised based on OMERACT principles for reviewing aims/objectives, defining the scope, identifying the important research questions and selecting key domains. Results. Following the initial multistakeholder meeting, subsequent teleconferences and email communications: consensus was obtained on the most important and relevant research questions; agreement on how the OMERACT Core Areas (life impact, pathophysiological manifestations, resource use and death) could form the basis of a MCD; and consensus on 22 items for inclusion into a MCD. Workshops were undertaken for two essential items that required further exploration: work/social participation and comorbidity. Conclusion. Reaching a consensus for the 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 for selecting instruments for two important items and for achieving compatibility with other UK national initiatives, and more widely across Europe.