The pattern of anti-IL-6 versus non-anti-IL-6 biologic disease modifying anti-rheumatic drugs use in patients with rheumatoid arthritis in Wales, UK: a real-world study using electronic health records

Objective: Investigating factors associated with drug initiation and discontinuation in patients treated with anti-IL-6 biologic DMARDs (bDMARDs) (tocilizumab or sarilumab) vs non-anti-IL-6 (anti-TNF, B or T cell therapies) bDMARDs for RA.

Methods: A retrospective cohort study of patients with the diagnosis of RA in the Secure Anonymised Information Linkage Databank, comprising primary and secondary care and specialist rheumatology clinic records for >90% of the population in Wales, UK. Patients initiated on first bDMARD treatment, discontinuation and clinical outcomes including infection and hospitalisation were analysed using Cox regression analysis.

Results: Of patients identified with RA in their primary care records, 95.7% (4691/4922) received conventional synthetic DMARDs (csDMARDs). More than one-third (36.2%) were treated with bDMARDs (1784/4922). Of these biologic-naïve patients, 6.5% (116) were treated with anti-IL-6 bDMARDs; this treatment was associated with a previous history of infection [difference 8.8% (95% CI 1.1, 17.8)] and kidney disease [14.3% (95% CI 8.0, 22.5)]. Treatment discontinuation was significantly higher in the non-anti-IL-6 bDMARD-treated patients (23.1%) compared with the anti-IL-6 bDMARD-treated individuals (18.1%) [difference 9.4% (95% CI 1.1, 15.7)]. For those discontinuing a first line of treatment, 385 patients (23%) and 21 patients (18%) switched to an alternative bDMARD from the non-anti-IL-6 and anti-IL-6 groups, respectively.

Conclusion: Comorbidities, history of infection and kidney disease were associated with choosing anti-IL-6 bDMARDs in biologic-naïve RA patients in Wales. Anti-IL-6 bDMARD-treated biologic-naïve patients were more likely to continue treatment than non-IL-6 bDMARD-treated patients.