Rapid improvement of Clinical Disease Activity Index (CDAI) at 3 months predicts a preferable CDAI outcome at 1 year in active rheumatoid arthritis patients treated with tocilizumab: results from an observational investigation of daily clinical practice.

OBJECTIVES: To investigate whether the Clinical Disease Activity Index (CDAI) at three months predicts a preferable CDAI outcome at one year in patients with active rheumatoid arthritis (RA) treated with tocilizumab (TCZ).

METHODS: Seventy-eight RA patients in the Nagasaki Prefecture, Japan, whose disease activities at baseline were moderate to high as estimated by the CDAI and who had received 8 mg/kg of TCZ every four weeks, were consecutively enrolled in this study from April 2008 to March 2011. The association of the CDAI at three months with that at one year was examined by the Cochran-Armitage test. The variables at baseline and at three months that were predictive of remission or low disease activity (LDA) according to the CDAI at one year were assessed by logistic regression analysis.

RESULTS: Most of the patients (40 out of 44: 91%), whose CDAI at three months showed remission or LDA continued to show remission or LDA at one year. Disease activity at three months significantly correlated with the frequency of LDA or remission at one year (p<0.0001). Logistic regression analysis revealed that only remission or LDA at three months as determined by the CDAI was predictive of remission or LDA at one year as determined by the CDAI (odds ratio 33.2, p<0.0001).

CONCLUSIONS: A preferable clinical outcome as estimated by the CDAI at one year in active RA patients treated with TCZ is predicted by the CDAI at three months, suggesting that the treat-to-target strategy carried out using the CDAI can be used in clinical practice in these patients.