Treatment with adalimumab in patients with chronic inflammatory rheumatic diseases: a study of treatment trajectories on a patient level in routine care.

BACKGROUND

Previous experiences with non-medical switching of adalimumab (ADA) in patients with chronic inflammatory rheumatic diseases (CIRD) come mainly from phase III extension of randomised clinical trials and little from routine care.

OBJECTIVES

To analyse treatment trajectories over 2 years in patients with CIRD conducting a non-medical switch from originator to biosimilar ADA.

DESIGN

A retrospective observational cohort study was conducted with data from a third-level rheumatology centre in Germany. CIRD patients on originator ADA who switched to ADA biosimilar from October 2018 onwards were identified and followed until September 2020.

METHODS

Patients' characteristics were compared between the four defined treatment trajectories 'continued biosimilar ADA therapy', 'back-switch to originator ADA therapy', 'switch to another biological disease-modifying anti-rheumatic drug (bDMARD) therapy' and 'stopped bDMARD therapy/death/drop out'. Factors associated with continuing biosimilar ADA therapy were analysed using Cox proportional hazards regression analyses.

RESULTS

A total of 121 CIRD patients were included. Most patients (66.9%) continued therapy with biosimilar ADA over 2 years, with a treatment retention rate of 73.1%. Whereas 21 patients (17.4%) switched back to originator ADA, mainly due to adverse events, and 8 patients (6.6%) switched to a different bDMARD, mainly due to lack of effect. The estimated risk of withdrawal was lower for longer prior duration on originator ADA [hazard ratio (HR): 0.82; 95% CI: 0.69-0.97] and higher for higher C-reactive protein levels at baseline (HR: 1.18; 95% CI: 1.00-1.39). Male patients, older patients and those for whom originator ADA was their first bDMARD tended to have a lower risk of withdrawal.

CONCLUSION

Our results indicated that three of four patients continue biosimilar ADA over 2 years with lower risks of withdrawal for male sex, older age, longer prior duration on originator ADA and originator ADA as first bDMARD.