Multiple DMARD discontinuations in rheumatoid arthritis: how often and in what patients? Results from a national clinical RA register.

Objectives: Multiple discontinuations of biologic (b-) or targeted synthetic (ts-) disease-modifying antirheumatic drugs (DMARDs) may indicate difficult-to-treat disease. We aimed to assess the occurrence of b/tsDMARD discontinuations in patients with rheumatoid arthritis (RA), specifically how this varies by definition, across patient subsets and over time.

Methods: Observational cohort study using data from the Swedish Rheumatology Quality Register on patients diagnosed with RA between 2010 and 2019. We identified three populations: (1) newly diagnosed (N=17 780), (2) initiating a first-ever DMARD (N=18 038) and (3) initiating a first-ever b/tsDMARD (N=8075). In each, we assessed the proportions and characteristics of patients fulfilling either of seven alternative DMARD discontinuation criteria (each encompassing a unique combination of number and type(s) of b/tsDMARD).

Results: At 4.5 years of follow-up, 10% in populations (1) and (2), and 25% in (3), had discontinued ≥2 b/tsDMARDs with different modes of action. The proportions meeting each of the other six definitions ranged from 0.3% to 10% in (1) and (2), and 1% to 25% in (3). Regardless of definition or time, the characteristics of discontinuers across populations (1) through (3) remained largely similar.

Conclusions: Applying treatment discontinuation-based definitions to an unselected RA population identifies widely varying proportions of patients with largely similar characteristics. Quantitatively, treatment-based definitions, follow-up time and study population must be clearly specified; qualitatively, the specific definition may be less critical.