Interleukin-23 and its correlation with disease activity, joint damage, and functional disability in rheumatoid arthritis.

The purpose of this study was to compare the serum interleukin (IL)-23 levels between rheumatoid arthritis (RA) patients and healthy controls and to determine the correlation of IL-23 levels with disease activity, joint damage and functional disability in RA. Serum samples were obtained from 45 patients with RA and 45 healthy controls. The enzyme-linked immunosorbent assay method was used for quantitative analysis of IL-23. All the RA patients were assessed for disease activity based on the 28-joint disease activity score, joint damage based on modified Sharp score, and functional ability using the Health Assessment Questionnaire-Disability Index. The mean serum IL-23 level was much higher among the RA patients (24.50 ± 13.98 pg/mL) compared to the controls (5.98 ± 3.40 pg/mL; p < 0.01). There was a significant positive relationship between IL-23 levels and disease activity and questionnaire scores (p = 0.003 and 0.020, respectively). On logistic regression analysis, IL-23 levels were significantly higher in patients with moderate to high disease activity (p = 0.008, odds ratio = 1.073, 95% confidence interval = 1.019-1.130) and patients with significant functional disability (p = 0.008, odds ratio = 1.085, 95% confidence interval = 1.021-1.153). RA patients have significantly higher levels of serum IL-23. The IL-23 levels correlate well with disease activity and functional disability but not with radiographic joint damage.