Background Clinical Disease Activity Index (CDAI) is considered to be suitable to monitor the efficacy of tocilizumab (TCZ)-treated patients with rheumatoid arthritis (RA) (Ref. 1). We have recently revealed that baseline low CDAI predicts the state of remission estimated by CDAI at 1 year in patients with RA treated by TCZ (Ref. 2). Therapeutic strategy of Treat to Target (T2T) states the importance of disease activity at 3 months of the treatments considering the better clinical outcome of RA.
Objectives To investigate whether CDAI at 3 months predict the disease activity estimated by CDAI at 1 year in active RA patients at baseline treated by TCZ.
Methods The RA patients at Nagasaki Prefecture, Japan, who had received 8 mg/kg of TCZ every 4 weeks were consecutively enrolled in this study from April 2008 to March 2011. A total of 110 RA patients were observed for 1 year from the initial infusion of TCZ. Among these 110 patients, we have selected 78 patients whose disease activities at baseline were moderate to high estimated by CDAI and the change of CDAI of these patients was evaluated every 3 months for 1 year through Last Observational Carried Forward (LOCF) method. The associations of CDAI at 3 months with that at 1 year were examined by the Cochran-Armitage test.
Results The median age, disease duration, CRP, ESR, and CDAI at entry were 59.6 years old, 11 years, 2.8 mg/dL, 59 mm/hr, and 27.1, respectively. As a whole, the decrement of CDAI was significant at 3 months to 1 year. Most of the patients (forty out of 44: 91%), whose CDAI at 3 months remission or low disease activity, had continued in remission or LDA at 1 year. In contrast, the half of the patients (twelve out of 25: 48%), whose CDAI at 3 months moderate disease activity, was induced in in remission or LDA at 1 year. Furthermore, only the small of the patients (one out of 9: 11%), whose CDAI at 3 months high disease activity, was induced in in remission or LDA at 1 year. The Cochran-Armitage test revealed significant correlations of CDAI at 3 months with that at 1 year (p <0.0001).
Conclusions Better clinical outcome of active RA patients treated with TCZ at 1 year can be predicted by the disease activity at 3 months, indicating an importance in consideration of T2T strategy toward these patients.
Kawashiri SY, et al. Disease activity score 28 may overestimate the remission induction of rheumatoid arthritis patients treated with tocilizumab: comparison with the remission by the clinical disease activity index. Mod Rheumatol. 2011;21:365-9.
Kawashiri SY, et al. Baseline low Modified Health Assessment Questionnaire (MHAQ) predicts the state of remission estimated by Clinical Disease Activity Index and MHAQ at 1 year in tocilizumab-treated rheumatoid arthritis patients. Clin Exp Rheum. In press.
Disclosure of Interest None declared