Lack of clinical disease activity response at 4 weeks of baricitinib treatment as a negative predictor of remission at weeks 12 and 24 in patients with rheumatoid arthritis: results from two phase 3 studies (RA-BEAM and RA-BEGIN)

Objective: To determine whether early changes in disease activity predict later achievement of low disease activity (LDA) or remission in patients treated with baricitinib 4 mg in global phase 3 studies. Methods: This analysis examined 487 patients and 159 patients randomized to baricitinib 4 mg in RA-BEAM and RA-BEGIN, respectively. Early response was predefined as Clinical Disease Activity Index (CDAI) improvement from baseline to Week 4 of ≥6.0. LDA and remission were based on Simplified Disease Activity Index at Weeks 12 and 24. Results: At Week 4, the majority of baricitinib-treated patients had CDAI improvement ≥ 6.0 in RA-BEAM (86%) and RA-BEGIN (85%), with high LDA/remission rates at Weeks 12 and 24. Negative predictive values (NPVs) based on CDAI improvement < 6 from baseline to Week 4 exceeded 90% for remission at Week 24. In comparison, NPVs for LDA at Week 24 were lower (RA-BEAM, 80%; RA-BEGIN, 58%). Conclusion: CDAI improvement ≥ 6.0 at Week 4 was associated with improved clinical outcomes at Weeks 12 and 24 whereas patients who were early non-responders were unlikely to achieve remission at these time points.