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.

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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. 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. 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. 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.