Background/Purpose: A recent randomized controlled study in a single country reported rates of disease worsening over a one-year follow-up period for innovator infliximab (IFX) and a comparator in various diseases including AS and RA. After a mean duration of treatment of 6.7 years of IFX, rates for disease worsening post-one year follow-up were 39.5% in AS and 36.7% in RA¹. Other such data reporting disease worsening rates are rare. Using data from a longitudinal database, the objective was to determine the incidence of disease worsening in AS and RA patients on long-term therapy with IFX. PsA patients were not included in this study due to low numbers (n=49).

Methods: BioTRAC is an ongoing, prospective registry of inflammatory arthritis patients initiating treatment with infliximab, golimumab or ustekinumab that has been ongoing since 2002 in Canada. We included AS and RA patients who had been on IFX therapy for at least two, four or six years. Disease worsening endpoint was defined as follows¹: for AS patients; an increase in ASDAS ≥ 1.1 from baseline and a minimum score of 2.1. For RA patients; an increase in DAS28 ≥ 1.2 from baseline and a minimum score of 3.2.

Results: This analysis included a total of 196 AS and 425 RA patients. Among AS patients, 36.1% were female, 90.8% were bionaïve at IFX initiation and 50% were on concomitant NSAID(s) at the 2-year index. The mean (SD) ASDAS score was 2.17 (1.05). As for the RA patients, 75% were female, 88.5% were bio-naïve, and 93% were on concomitant DMARD(s) while 35% were on corticosteroids at the 2-year index. The mean (SD) DAS28 ESR and DAS 28 CRP were 3.37 (1.40) and 3.00 (1.24), respectively. As shown in table 1, the incidence of disease worsening in AS and RA patients on stable IFX for 2-6 years was low and varied from 2.7% to 11.5% at the subsequent 12 and 24 months visit.

Conclusion: In this prospective longitudinal cohort, patients on long-term IFX therapy show low rates of disease worsening of 2.7% to 11.5% at 1 and 2 years in AS and RA. Additional studies may elucidate the true rate of and reasons for disease worsening in rheumatologic populations.

Table 1. Incidence of disease worsening in AS and RA patients at the 2, 4, and 6-year index

Reference: ¹Jørgensen KK, et al. Switching from originator infliximab to biosimilar CT-P13 compared with maintained treatment with originator infliximab (NOR-SWITCH): a 52-week, randomised, double-blind, non-inferiority trial. The Lancet 2017; doi: 10.1016/S0140-6736(17)30068-5.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/incidence-of-disease-worsening-in-inflammatory-arthritis-patients-on-long-term-infliximab-remicade-therapy/