Comparison of characteristics of international and national databases for rheumatoid arthritis: a systematic literature review

To evaluate current (inter)national registers and observational cohorts in Europe, and to compare inclusion criteria, aims, collected data, and participation in the European League Against Rheumatism (EULAR) repository. We performed a systematic search strategy in six literature databases for rheumatoid arthritis (RA). Publications reporting European (inter)national prospective registers/cohorts including > 200 RA patients with at least half a year of follow-up were selected. In total, 417 articles and abstracts were included from four international databases and 39 national databases/cohorts. International databases were of similar design, frequency of data collection and selection criteria and are mostly initiated to monitor and compare clinical patient care among countries. National databases/cohorts vary in aims and inclusion criteria. Half of the national registers are connected to the EULAR repository of databases. Our findings indicate that, among researchers, there is little awareness of guidelines to set up registers or cohorts and of the existence of the database collaboration network of EULAR