Does a mandatory non-medical switch from originator to biosimilar infliximab lead to increased use of outpatient healthcare resources? A register-based study in patients with inflammatory arthritis

OBJECTIVES: National Danish guidelines in May 2015 dictated a mandatory switch from originator infliximab (INX) to biosimilar CT-P13 in patients with inflammatory rheumatic disease. We investigated if this non-medical switch changed use of outpatient hospital resources. METHODS: Observational cohort study. Switchers were identified in DANBIO. Rheumatic outpatient contacts, visits and services were identified in the National Patient Registry. The 6-month rate for (1) number of visits (or services) and (2) days with ≥1 visit (or service) were compared before/after switching (paired t-tests). Visits per week per patient before/after the switch date were analysed with graphical interrupted time-series analysis. RESULTS: In 769 switchers (372 males, median age 54 years (IQR 44–66)), 1484 outpatient contacts, 6718 visits and 9243 days with services (693 on switch date) were identified. Mean visit rate was 3.89 before and 3.95 after switch (p=0.35). Total number of services was 19 752 (2019 on switch date). Mean rates before/after switch for 16 service categories were small and differences close to zero. Visits per week per patient appeared similar before/after switch with peaks every ≈8 weeks (standard INX infusion interval). CONCLUSION: Changes were marginal with no clinically relevant increase in use of outpatient health care resources 6 months after compared with 6 months before mandatory switch from originator to biosimilar infliximab.