Objective: To evaluate published proposed definitions of minimal disease activity (MDA) and remission in patients with early rheumatoid arthritis (RA).
Methods: The cohort comprised disease-modifying antirheumatic drug (DMARD)-naive patients with early seropositive active RA (n = 200) treated with traditional DMARDs in the prebiologic era. MDA definitions included Disease Activity Score in 28 joints (DAS28) <or=2.85, or achieving 5 of 7 World Health Organization (WHO)/International League of Associations for Rheumatology (ILAR) core set measure thresholds as proposed by the Outcome Measures in Rheumatology Clinical Trials. Other MDA definitions included Simplified Disease Activity Index (SDAI) score <or=11 and Clinical Disease Activity Index (CDAI) score <or=10. Remission definitions included American College of Rheumatology (ACR) remission, DAS28 <2.6, DAS28 <2.4, achieving all 7 WHO/ILAR core set measure thresholds, SDAI <or=3.3, and CDAI <or=2.8. Physical function was assessed using the Health Assessment Questionnaire (HAQ) disability index (DI) and radiographic progression was assessed using the Sharp score.
Results: At baseline, no patients were in MDA or remission. Depending on the MDA definition, 20-32%, 27-32%, and 30-48% were in MDA at 6, 12, and 24 months, respectively. Depending on the remission definition, 0.7-15%, 0-24%, and 0-33% were in remission at 6, 12, and 24 months, respectively. For example, at 6 months, lowest (highest) responses for MDA were seen with DAS28 <or=2.85 (SDAI <or=11) and for remission with ACR remission criteria (DAS28 <2.6). Patients who achieved either MDA or remission had lower HAQ DI and radiographic scores compared with patients who achieved neither.
Conclusion: Our study demonstrated that different proportions of patients were classified as MDA or remission depending on the definition used. This has implications in predefining MDA or remission for a clinical trial or to establish goals for optimum management of RA in clinical practice.