Demographic, clinical and therapeutic data at the time of an enrollment in IORRA.

*Maximum value of RF measured in the cohort project during 2000–2010 for each individual was used.
†Cut-off  = 4.5 IU/ml.
IORRA, Institute of Rheumatology Rheumatoid Arthritis cohort study; BMI, body mass index; DAS28, disease activity score in 28 joints; J-HAQ, the Japanese version of Health Assessment Questionnaire; RF, rheumatoid factor; ACPA, anti-citrullinated peptide antibody; TKR, total knee replacement; DMARDs, disease modifying antirheumatic drugs.