Association between Interleukin-6 Levels, Rituximab Response, and Disease Activity in Patients with Rheumatoid Arthritis

Background: Interleukin-6 (IL-6) significantly affects rheumatoid arthritis (RA) and its associated conditions, playing a crucial role in acute inflammation by promoting the synthesis of most acute-phase proteins. Aim: The present study aimed to assess the potential association between Rituximab (RTX) response and IL-6 level in RA patients Patients and method: The current study was conducted in Baghdad-Iraq during the period from January to March 2023. The study included a convenient sample of ninety adult patients who were already diagnosed with RA and received intravenous infusions of RTX for at least six months. Clinical Disease Activity Index (CDAI) was adopted to evaluate RA activity. Results: The proportion of patients with high disease activity according to CDAI was significantly higher in the RTX non-responders group compared to the RTX responders’ group. The IL-6 level was significantly higher in the RTX non-responders’ group than in the RTX responders’ group (P-value<0.001). The IL-6 level was significantly higher in patients with high disease activity than other patients. Conclusion: In RA patients who treated with RTX, IL-6 levels are correlated with increased clinical disease activity and may be used as a proxy for RTX responsiveness in RA patients.