Fig. 1.

Treatment courses. Patients with RA were categorized as having undergone single therapy, interrupted therapy, or switched therapy. Patients in the single and interrupted therapy categories received one TNFi agent (“TNFi 1”) during the observation period, while patients in the switched therapy category received two TNFi agents (“TNFi 1” and “TNFi 2”) during the observation period. Patients could have undergone only a first course of treatment (i.e., the single therapy patients) or a first and second course (i.e., the interrupted and switched therapy patients); second courses of treatment began after a treatment gap 90 or more days (for interrupted therapy patients) or after initiation of a second TNFi agent (for switched therapy patients). TNFi tumor necrosis factor inhibitor, RA rheumatoid arthritis