Background/Purpose: Biologic therapy has revolutionised the treatment of rheumatoid arthritis (RA). Randomised control trials have shown that IL-6 inhibitors are superior to adalimumab, a TNF inhibitor, when used as monotherapy in RA. However more information is required to assess the real-life burden and to predict infection risk in RA patients using biologics and IL-6 receptor antibodies. Here, we describe the characteristics and comorbidities of RA patients treatment with either IL-6 inhibitors, (tocilizumab or sarilumab) versus non-IL-6 (anti-TNF, B-or T-cell therapies) biologic disease modifying anti-rheumatic drugs (bDMARDs).

Methods: A retrospective cohort study of patients with the diagnosis of RA in the Secure Anonymised Information Linkage (SAIL) databank, which includes primary care, secondary care and specialist rheumatology clinic records of over 90% of the population in Wales, UK. Patients treated with IL-6 inhibitors or biologics are compared in a descriptive study and include both biologic/il6-inhibitor naïve and non-naïve patients. Funding and acknowledgement: This study was funded a grant from Sanofi (20190412).

Results: Of 4,922 patients identified with RA in their primary care records, 95.7% (4,691/4,922) received csDMARD treatment. Over a third of patients (36.2%) were treated with bDMARDs (1,784/4,922).Of these biologic-naïve patients, 116 (6.5%) were treated with IL-6 inhibitors. Treatment with IL-6 bDMARDs was associated with previous history of infection (difference: 8.8%, 95% CI 1.1 to 17.8) and kidney disease (14.3% 95% CI 8.0 to 22.5). The rate of treatment failure was significantly higher in the non-IL-6 bDMARDs-treated patients (23.1%) compared to the IL-6 inhibitor treated individuals (18.1%) (difference: 9.4%, 95% CI: 1.1 to 15.7). Orthopaedic surgery pre-treatment and steroid use was associated with non-IL-6 bDMARDs treatment failure (HR: 1.64, 95% CI: 1.00 to 2.68; HR: 1.62, 95% CI: 1.26 to 2.08, respectively). Post-treatment infection rate was higher with non-IL-6 bDMARDs (difference: 10.5%, 95% CI: 3.7 to 19.0) than IL-6 bDMARDs. Orthopaedic surgery was also more common in non-IL-6 bDMARDs (difference: 9.9%, 95% CI: 4.1 to 13.3). No factor was found to be associated with treatment failure in the IL-6 inhibitor treated patients which may be due to fewer number of patients. 385 patients (23%) and 21 patients (18%) switched to alternative bDMARD from the non-IL-6 and IL-6 groups respectively. Of the 385 switchers from the non-IL6 bDMARD group, 298 patients (77.4%) received a second non-IL-6 bDMARDs and 87 patients received IL-6 bDMARDs (22.5%). Treatment failure in biologic-experienced patients was significantly higher in the IL-6 bDMARD treated group (difference: 28.3%, 95% CI: 17.6 to 39.3). The patient characteristics were not significantly different between the two groups.

Conclusion: Comorbidities, previous history of infection and previous history of kidney disease, were associated with choosing IL-6 bDMARDs in biologic naïve RA patients in Wales. IL-6 treated biologic-naïve patients were more likely to continue treatment than non-IL-6 biologic treated patients. The reverse is the case in biologic-experience patients.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/previous-history-of-serious-infection-is-associated-with-the-use-of-il-6-inhibitors-in-rheumatoid-arthritis-in-wales-uk/