Factors Determining the Switch of the First Biological Treatment in Spondyloarthritis: Data from the RBSMR Registry

Despite the substantial progress made in the therapeutic management of spondylarthritis (SpA) after the advent of biotherapy, some patients still undergo, for various reasons, therapeutic switches to an alternative biological agent. This study aimed to identify the factors leading to the switch from the initial biological treatment in patients with SpA, with a view toward tailoring the prescription to the patient's profile.

Adult patients (aged >18 years) with spondylarthritis treated with biotherapy were enrolled in a cohort derived from a national historical-prospective multicenter registry between June 2017 and January 2019. The selection was based on the ASAS criteria, and patients were assessed every six months with a planned three-year follow-up. Baseline demographics and disease characteristics at the time of biologic therapy initiation were collected. Factors determining the switch to first bDMARDs were identified through univariate and multivariate logistic regression, reporting odds ratios (OR) with 95% confidence intervals (CI).

A total of 194 SpA patients were included. By the end of follow-up, 46 patients (23.71%) had switched to a second biologic agent (TNFα inhibitor or secukinumab). This switch was significantly associated with: advanced age (p = 0.030), higher Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) (p = 0.024), and the absence of specific comorbidities, including heart disease and stroke (p = 0.011 for both).

The new bio-medications have considerably improved the prognosis of patients suffering from chronic inflammatory rheumatism, necessitating regular monitoring to detect events that could lead to a treatment switch. In our study, we identified factors associated with therapeutic switching, particularly advanced age, a history of corticosteroid therapy, and specific comorbidities. These findings highlight potential risk factors; however, further studies with larger cohorts and immunogenicity data are required before firm clinical recommendations can be made.