Objective: To compare the performance of different definitions of remission in a large multinational cross-sectional cohort of patients with rheumatoid arthritis (RA).
Methods: The Questionnaires in Standard Monitoring of Patients with RA (QUEST-RA) database, which (as of January 2008) included 5,848 patients receiving usual care at 67 sites in 24 countries, was used for this study. Patients were clinically assessed by rheumatologists and completed a 4-page self-report questionnaire. The database was analyzed according to the following definitions of remission: American College of Rheumatology (ACR) definition, Disease Activity Score in 28 joints (DAS28), Clinical Disease Activity Index (CDAI), clinical remission assessed using 42 and 28 joints (Clin42 and Clin28), patient self-report Routine Assessment of Patient Index Data 3 (RAPID3), and physician report of no disease activity (MD remission).
Results: The overall remission rate was lowest using the ACR definition of remission (8.6%), followed by the Clin42 (10.6%), Clin28 (12.6%), CDAI (13.8%), MD remission (14.2%), and RAPID3 (14.3%); the rate of remission was highest when remission was defined using the DAS28 (19.6%). The difference between the highest and lowest remission rates was >or=15% in 10 countries, 5-14% in 7 countries, and <5% in 7 countries (the latter of which had generally low remission rates [<5.5%]). Regardless of the definition of remission, male sex, higher education, shorter disease duration, smaller number of comorbidities, and regular exercise were statistically significantly associated with remission.
Conclusion: The use of different definitions of RA remission leads to different results with regard to remission rates, with considerable variation among countries and between sexes. Reported remission rates in clinical trials and clinical studies have to be interpreted in light of the definition of remission that has been used.