Shorter disease duration is important for tocilizumab to achieve Boolean remission.

OBJECTIVE: To determine the optimal conditions for inducing rheumatoid arthritis (RA) into disease remission by tocilizumab (TCZ), we analyzed the TCZ therapy carried out in our facility.

METHOD: The study group comprised 116 patients with RA who started TCZ therapy at Kobe University Hospital and Konan-Kakogawa Hospital. The clinical response to TCZ was evaluated by the 2011 Boolean definition and the disease activity score of 28 joints erythrocyte sedimentation rate 4 (DAS28-ESR4).

RESULTS: After 24 weeks of TCZ therapy, 25.9% of the patients achieved a Boolean-defined disease remission (Boolean remission). DAS28-ESR4 was improved from 5.25 ± 1.15 at week 0 to 2.75 ± 1.34 at week 24 (mean ± SD, P < 0.0001), and 57.8% patients achieved DAS28 remission. Analysis of the relationship between disease duration and remission showed that this odds ratio peaked at 3.0 years. Univariate analyses showed that Boolean remission was associated with baseline ESR levels, Steinbrocker's class and stage, and patient global assessment of disease activity (PGA). Accordingly, we categorized and compared the patient groups referring to the 3.0-year peak. We found significant differences in Steinbrocker's class and stage.

CONCLUSION: TCZ therapy leading to Boolean disease remission is optimal when initiated less than 3.0 years after disease onset.