<![CDATA[Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease that affects about 1% of the general population. It is characterized by chronic, progressive, and systemic inflammation. Interleukin-33 (IL-33), is a pro-inflammatory cytokine that is believed to be involved in joint inflammation in RA. This cross-sectional research aims to determine if interleukin-33 (IL-33) could serve as a potential biomarker for RA diagnosis and evaluation of activity of RA. The research involved 132 patients with inflammatory arthritis, and their serum levels of IL-33 and anti-citrullinated peptide antibody (ACPA) were measured using ELISA. Other routine biomarkers, including C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and rheumatoid factor (RF), were also measured. The median (IQR) of IL-33 was significantly lower in patients with RA [10.576 pg/mL (7.920)] than in those with other types of inflammatory arthritis [12.896 pg/mL (5.700)]. The study also revealed a non-significant difference in IL-33 levels among the four disease activity groups according to DAS-28 ESR and DAS-28 CRP (P = 0.830, P = 0.340, respectively). Additionally, IL-33 had a significant negative correlation with age (P = 0.019) and diabetes mellitus (P = 0.032). To the best of our knowledge, this study is the first to evaluate IL-33 as a diagnostic tool, showing a sensitivity of 59.8% and a specificity of 72% at a cut-off value of ≤11.8207 pg/mL. IL-33 test alone is not sufficient for the diagnosis of RA or differentiating it from other types of inflammatory arthritis. Also, it cannot be used as a routine biomarker for the evaluation of RA activity.]]>
