Treatment Patterns of Rheumatoid Arthritis in Japanese Hospitals and Predictors of the Initiation of Biologic Agents

Objective: To describe the usage of different biologic agents for rheumatoid arthritis (RA) in Japan over time and to identify factors that affects the decision to initiate treatment with biologic agents. Determinants of a switch to another biologic agent for patients who are already on biologic treatment were also analyzed. Research design and methods: We utilized a hospital claims database containing 36,504 Japanese patients with a confirmed RA diagnosis. To analyze the determinants of treatment choices, we applied logistic regression analysis taking into account socio-demographic and medical factors. Results: Analyses determined that 11.8% of diagnoses and 25.4% of treated patients in Japan receive a biologic agent. Significant factors associated with biologic treatment initiation include younger age, female sex, and a higher comorbidity index. The route of administration plays a major role when it comes to a switch between different biologic agents. Conclusions: The lower likelihood of elderly patients to be initiated on biologic treatment might be explained by the risk aversion of Japanese physicians' and patients who are afraid of the potential side effects of biologics. This finding is also consistent with the notion of an age bias that impedes elderly patients from optimal access to biologic treatment. Because claims data does not contain clinical parameters such as disease activity the results should be validated in a clinical context.