Utilization Patterns Of Infliximab Originator To Infliximab Biosimilar In Us Veterans

BACKGROUND: The study objective was to describe utilization of infliximab (IFX) products, including the infliximab originator Remicade (IFX-orig) and biosimilars Inflectra (IFX-dyyb), and Renflexis (IFX-abda), during a 6-month follow-up period. METHODS: Data were collected from national Veterans Affairs (VA) administrative and electronic medical record datasets between September 1, 2016 to December 31, 2019. The index date was the first infliximab biosimilar dispensation date during the study period. Veterans were required to be enrolled in the VA for >365 days prior to their index date. Veterans were sub-grouped according to their history of infliximab exposure prior to the index date (IFX-naïve or IFX-experienced), and disease indication (Crohn’s Disease (CD), Ulcerative Colitis (UC), Rheumatoid Arthritis (RA), Ankylosing Spondylitis (AS), Psoriatic Arthritis (PsA), Psoriasis (PsO), and Others). The distribution of patients on each IFX product was assessed over time. Persistence on the index product and proportion of patients switching to a different IFX product were determined. Other measures of IFX utilization included the average weight-based dose, cumulative dose, the number of dispensed doses, and proportion of days covered (PDC). RESULTS: Among 5,227 veterans, the mean age was 54.5 (95% CI: 54.1-55.0) years and 88.4 (87.6-89.3)% were male. 70.2 (69.0-71.4)% were initiated on IFX-orig, 13.4 (12.5-14.4)% IFX-dyyb, and 16.4 (15.4-17.4)% IFX-abda. 51.2 (49.9-52.6)% were IFX-naïve. Disease indications included CD (40.1 (38.7-41.4)%), UC (26.7 (25.5-27.9)%), RA (12.0 (11.1-12.9)%), AS (5.9 (5.3-6.6)%), PsA (5.4 (4.8-6.0)%), PsO (2.3 (1.9-2.7)%), and Others/Unknown (7.6 (6.9-8.4)%). The percentage of IFX users on a biosimilar increased between the beginning and end of the study (from 0.1% to 86%). The percentage of Veterans persistent on their index IFX product throughout the 6-month follow-up period was 78.2%. Within the subset of Veterans who were not persistent on their index IFX product, 26.4% switched to a different IFX product. The mean number of times IFX was dispensed during the 6-month follow-up was 4.25 (4.20-4.30) (IFX-orig 4.24 (4.19-4.30), IFX-dyyb 4.07 (3.93-4.22), IFX-abda 4.41 (4.28-4.53)). The average weight-based dose was 5.95 (5.89-6.01) mg/kg (IFX-orig 6.09 (6.02-6.17) mg/kg, IFX-dyyb 5.70 (5.56-5.83) mg/kg, IFX-abda 5.56 (5.44-5.67) mg/kg) and the mean cumulative dose was 2331.9 (2291.8-2371.9) mg (IFX-orig 2390.7(2341.7-2439.7) mg, IFX-dyyb 2120.1 (2015.9-2224.3) mg, IFX-abda 2253.3 (2162.9 – 2343.6) mg). The mean PDC was 0.86 (0.85-0.86) (IFX-orig 0.88 (0.87-0.88), IFX-dyyb 0.78 (0.76-0.80), IFX-abda 0.83 (0.81-0.85)). Additional IFX utilization data will be subsequently presented for the subpopulations with Crohn’s and UC. CONCLUSION: The percentage of IFX users on a biosimilar increased throughout the study period. Dosing outcomes and PDC were similar with IFX-orig, IFX-dyyb and IFX-abda, suggesting biosimilars were used in a similar manner as the originator product.