IL-6 inhibitors and JAK inhibitors as favourable treatment options for patients with anaemia and rheumatoid arthritis: ANSWER cohort study

Rheumatology (Oxford). 2024 Feb 1;63(2):349-357. doi: 10.1093/rheumatology/kead299.


Objectives: Anaemia, a common comorbidity of RA, is related to high disease activity and poor prognosis. It is unknown which biologic/targeted synthetic (b/ts)-DMARDs are optimal for patients with anaemia and RA in regulating anaemia and controlling disease activity.

Methods: We investigated the change in haemoglobin (Hb) levels, drug retention rates and disease activities after the administration of b/ts-DMARDs with different modes of action [TNF inhibitors (TNFis), immunoglobulin fused with cytotoxic T-lymphocyte antigen (CTLA-4-Ig), IL-6 receptor inhibitors (IL-6Ris) and Janus kinase inhibitors (JAKis)] in patients with RA stratified by baseline Hb levels using the multicentre observational registry for patients with RA in Japan (ANSWER cohort).

Results: A total of 2093 patients with RA were classified into three groups based on tertiles of the baseline Hb levels (Hblow, anaemic; Hbint, intermediate; Hbhigh, non-anaemic). IL-6Ri increased Hb levels in all groups (the mean change at 12 months in Hblow was +1.5 g/dl, Hbint +0.7 g/dl and Hbhigh +0.1 g/dl). JAKis increased the Hb level in patients with anaemia and RA and retained or decreased the Hb level in non-anaemic patients (the mean change at 12 months in Hblow was +0.6 g/dl, Hbint 0 g/dl and Hbhigh -0.3 g/dl). In patients with anaemia and RA, overall adjusted 3-year drug retention rates were higher in JAKi followed by IL-6Ri, CTLA4-Ig and TNFi (78.6%, 67.9%, 61.8% and 50.8%, respectively). Change of disease activity at 12 months was not different among different b/ts-DMARDs treatments.

Conclusion: IL-6Ri and JAKi can effectively treat patients with anaemia and RA in a real-world setting.

Keywords: ANSWER cohort; Hb levels; IL-6; IL-6 receptor inhibitors; Janus kinase; RA; anaemia; disease activity; drug retention; synovitis.

MeSH terms

  • Anemia* / drug therapy
  • Anemia* / etiology
  • Antirheumatic Agents* / therapeutic use
  • Arthritis, Rheumatoid* / complications
  • Arthritis, Rheumatoid* / drug therapy
  • Cohort Studies
  • Humans
  • Interleukin-6 Inhibitors
  • Janus Kinase Inhibitors* / therapeutic use


  • Janus Kinase Inhibitors
  • Interleukin-6 Inhibitors
  • Antirheumatic Agents