Objectives. To investigate the relationship between changes in patient characteristics over time and the eff ectiveness and safety of adalimumab in the treatment of rheumatoid arthritis (RA) in clinical practice. Methods. Patients enrolled in the post-marketing registry study in Japan were divided into 5 subgroups based on the time adalimumab treatment was initiated. Demographic and baseline characteristics and responses to adalimumab were compared among the 5 subgroups to detect any time-course trend. Multiple logistic regression analysis was performed to identify characteristics that were signifi cantly associated with the eff ectiveness or safety of adalimumab and to estimate response rates and the incidence of adverse drug reactions in individual subgroups. Results. During the study period, patient characteristics changed signifi cantly over time, in particular with regard to prior biologic use and concomitant methotrexate therapy. There was a signifi cant trend toward higher response rates and lower incidence of infections and injection-site reactions in patients initiating adalimumab later in the study. Patient characteristics, such as concomitant methotrexate therapy and early stage RA, were signifi cant predictors of the eff ectiveness and safety of adalimumab. Conclusions. Patient characteristics have changed since adalimumab became available for the treatment of RA; several of these characteristics were signifi cant predictors of adalimumab eff ectiveness and safety.
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