Background/Purpose: In general, drug retention rate reflects the effectiveness and tolerability of the drug. In Japan, six biological agents have been approved for the treatment of rheumatoid arthritis (RA). There is few data comparing the retention rates between biological monotherapies for RA patients in daily clinical practice. The purpose of this study is to compare the drug retention rates of three biological monotherapies with different target molecules, etanercept (ETN), tocilizumab (TCZ), abatacept (ABT) .

Methods: We collected the data from the patients who started monotherapies with ETN, TCZ, ABT as first-biologics since 2008 and registered in the multicenter, large cohort of RA patients (Tsurumai Biologics Communication Registry; TBCR). We surveyed the following information: demographic data, disease activity (DAS28-CRP) at the baseline of each biological treatment. Drug retention rates were calculated by the Kaplan-Meier analysis and compared using the log-rank test among groups. We investigated drug retention rates for discontinuation due to insufficient effectiveness and adverse events.

Results: We analyzed 279 patients of 2072 patients registered in TBCR until March 2011 (141 patients in the ETN group, 63 patients in the TCZ group, 75 patients in the ABT group). The mean follow up time was 25.7 months. Table shows baseline characteristics of the groups (Table). The patients in the ABT group were older compared with other groups. Cumulative incidence rate for discontinuation due to insufficient effectiveness was significantly lower in the TCZ group (p=0.019, Fig.1A). Cumulative incidence rate for discontinuation due to adverse events was significantly lower in the ABT group (p=0.007, Fig.1B).

Conclusion: We demonstrated that TCZ monotherapy had a lower discontinuation rate due to insufficient efficacy and that ABT monotherapy had a lower discontinuation rate due to adverse events.