Changes in selected haematological parameters associated with JAK1/JAK2 inhibition observed in patients with rheumatoid arthritis treated with baricitinib.

Objective: To characterise changes in selected haematological parameters following once-daily oral baricitinib dosing.

Methods: Data were pooled from eight randomised clinical trials (four phase 3, three phase 2, one phase 1b) and one long-term extension. Changes in haematological parameters were evaluated up to 128 weeks (N=2387); overall safety of baricitinib was assessed up to 6 years (N=3492).