Association of patient- and hospital-level predictors with patterns of initial treatment in patients with Rheumatoid Arthritis: findings from a national cohort study

Objectives: To update the first-line conventional synthetic disease-modifying antirheumatic drugs (csDMARDs) prescribing pattern, describe change and variation across demographical and geographical factors in the Rheumatoid arthritis (RA) population, and identify individual and hospital factors associated with it.

Methods: This retrospective cohort study included newly diagnosed RA adult patients from 1 May 2018-1 April 2023 in the UK. We used adjusted multinomial logistic regression with random effect to explore associations with different first-line csDMRAD prescription and to account for hospital-level clustering.

Results: We identified 15 462 RA patients who got csDMARD treatment. Overall, 57% received methotrexate (MTX) monotherapy and 14% received MTX combination therapy as first-line treatment. MTX is the most frequently medication, following by Hydroxychloroquine and Sulfasalazine. Compared with non-MTX prescription, prescription of MTX monotherapy (adjusted Odds Ratio (aOR): 1.25 95%CI [1.22-1.29]) and MTX combination therapy (aOR: 1.45 [1.38-1.52]) was significantly higher in patients with higher DAS28, but lower in the non-white individuals with comorbidities: lung disease, cancer, fracture and heart attack. Among those received MTX, monotherapy is more likely be prescribed in patient with higher DAS28 (aOR: 1.08 [1.05-1.11]) and without lung disease (aOR: 0.5 [0.44-0.56]), compared with combination therapy. Around 20% of the variability in first-line csDMARD prescribing was attributed to the hospital level.

Conclusion: In this cohort study of new-onset RA population, both individual- and institution-level variation in first-line csDMARD treatment strategy was evident. Gender, ethnicity, disease activity, and comorbidities especially lung disease were associated with disparities at the individual level.