Effect of early treatment on physical function in daily management of rheumatoid arthritis: a 5‐year longitudinal study of rheumatoid arthritis patients in the National Database of Rheumatic Diseases in Japan

Aim The purpose of this study was to assess 5-year changes in physical function and factors associated with improvement among patients with rheumatoid arthritis (RA) in daily clinical practice, focusing on the effect of treatments, including biologic agents, in the early stage of disease course. Methods The National Database of Rheumatic Diseases by iR-net in Japan (NinJa) was searched for patients with disease duration ≤ 2 years and modified health assessment questionnaire (mHAQ) > 0 between 2004 and 2007, so that 510 patients were included in the final analysis. Multivariate-logistic regression analyses were used to identify predictors of 5-year mHAQ disability score improvement. Results Median mHAQ score was 0.40 at baseline and decreased to a median 0.17 after 5 years. Seventy-four percent of the patients were treated with methotrexate (MTX) and 25% with biologic agents, with early use of biologic agents (within 2 years of RA onset) increasing over time. Multivariate analyses identified higher baseline Disease Activity Score of 28 joints – C-reactive protein and early use of MTX (within 1 year of RA onset) and of biologic agents (within 2 years) as significantly associated with improved mHAQ; odds ratios of the early treatment were 1.83 (P = 0.01) for MTX and 2.23 (P = 0.04) for biologic agents, respectively. Conclusion Five-year mHAQ improved in early RA patients in the NinJa database. In daily clinical management of RA, likewise in clinical trials, early administration of MTX or biologic agents is able to improve physical function outcome.