Comparative risk of incident malignancies in rheumatoid arthritis patients treated with Janus kinase inhibitors or biologic disease-modifying antirheumatic drugs (bDMARDs): observational data from the German RABBIT register
Main finding · Incident malignancy (IR per 1000 patient-years)Result — go to the resultAdjusted hazard ratio 1.40 95% CI 1.09–1.80Authors' conclusion
In this German observational cohort study, an overall small increase in malignancy risk for JAKi vs bDMARD treatment was observed, with more pronounced risks in some subgroups of patients.
Study context
- Population
- Adults with RA in the German RABBIT register; Disease-modifying antirheumatic drug (DMARD) treatment episodes initiated January 2017–December 2020, followed up to June 2024treatment episodes
- Exposure
- JAKi vs bDMARD treatment
- Outcome
- Incident malignancies (excluding nonmelanoma skin cancer)
Methodological detailsregister-based (RABBIT), inverse probability weighted adjusted Cox models
- Register-based (RABBIT)
- Inverse probability weighted adjusted Cox models
Main finding
Incident malignancy (IR per 1000 patient-years)
Adjusted hazard ratio
1.40
95% CI 1.09–1.80
Events by group
JAKivs bDMARD
aHR 1.40 (95% CI 1.09–1.80)
As reported in the abstract
Observational data: associations, not effects.
Further findings
Malignancy risk by treatment episode duration
- Increased risk for JAKi vs bDMARD only in treatment episodes lasting longer than 16 months
Malignancy risk in subgroups
- Risk appeared higher in some subgroups, incl. treatment start aged ≥60 years, ≥3 prior csDMARD treatments, and high disease activity
Parts of this Brief are withheld: the automatic checks could not confirm them against the abstract.
Original publication
Comparative risk of incident malignancies in rheumatoid arthritis patients treated with Janus kinase inhibitors or bDMARDs: observational data from the German RABBIT register. Ann Rheum Dis. Published 26 June 2025. doi:10.
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