Estimation of interleukin-6 level and atherogenic indices as predictors of severity of rheumatoid arthritis in Iraqi patients

Background & Objective: Rheumatoid Arthritis (RA) is an inflammatory illness that causes joint degeneration and inflammation of the synovial membrane, leading to significant disability over time. Interleukin-6 (IL-6) is a widely distributed pro-inflammatory cytokine that has a variety of roles in several pathophysiologic systems, most notably in the RA development. The purpose of this study was to assess the blood levels of IL-6 and the severity and activity of RA in patients, and to assess the association of atherogenic indices with IL-6 as a predictor of severity in RA disease. Methodology: This study was a case control observational study involving 300 participants diagnosed with RA by the rheumatologists in accordance with American College of Rheumatologists (ACR)/ European League Against Rheumatism (EULAR) 2010 criteria. Serum levels of IL-6, CRP, RF and ACPA were measured by using ELISA technique. While, lipid profile was determined with spectrophotometry. Receiver operating curve (ROC) was used to study the opportunity of using atherogenic indices and IL-6 as diagnostic tools for RA. Results: The results indicated a higher IL-6 level in RA patients in comparison to the control group, e.g., 28.55 (18.76-41.07) pg/mLvs 10.19 (6.11-12.50) pg/ml. High atherogenic index of plasma (AIP) risk > 0.24 in RA patients parameters (GDF-15, IL-6), the lipid profile parameters and atherogenic indices (TC, TG, VLDL-C, LDL-C, CRI-I, CRI-II, AIP, and AC) were compared with moderate atherogenic risk (AIP < 0.24) in RA patients. While a significant decrease was recorded in the HDL-C and BMI levels, it had significantly high atherogenic risk (AIP > 0.24) compared with moderate atherogenic risk (AIP < 0.24) in RA patients. The ROC results analysis showed that the top 5 highly sensitive predictors for RA, e.g., CRI-I, AC, AIP, CRI-II followed by IL-6, have a relatively good sensitivity and specificities for predictors for RA. Conclusion: Increase in interleukin-6 may indicate the activity and severity of the disease. This biomarker could be helpful for early disease detection. The results showed a higher IL-6 in RA patients as well as increased dyslipidemia and atherogenicity in RA patients. Elevation of serum IL-6 and atherogenic indices are the best predictors for RA patients with a higher risk of atherosclerosis than other biomarkers. There is an important correlation between atherogenic indices parameters and the immunological biomarkers IL-6 indicating a significant role of the inflammation in the incidence of atherogenic indices in RA. Abbreviations: AUC- Area Under Curve; ACPA - Anti Cyclic Citrullinated Peptide Antibodies; CRP- C-Reactive Protein; ESR- Erythrocyte Sedimentation Rate; RF- Rheumatoid Factor; BMI- Body Mass Index; GDF-15 -Growth Differentiation Factor-15; DAS28-CRP- Disease Activity Score-28-C-Reactive Protein; TC- Total Cholesterol; TG- Triglyceride; HDL-C -High Density Lipoprotein Cholesterol; LDL-C -Low Density Lipoprotein Cholesterol; VLDL-C-Very Low Density Lipoprotein Cholesterol; AC-Atherogenic Coefficient; AIP-Atherogenic Index of Plasma; CR-I, CR-II- Castelli’s Risk Indexes. Keywords: Rheumatoid Arthritis, Interleukin-6, Atherogenic Indices. Citation: Abdulridha GAO, Hussein MA, Majeed SR. Estimation of interleukin-6 level and atherogenic indices as predictors of severity of rheumatoid arthritis in Iraqi patients. Anaesth. pain intensive care 2024;28(4):700−705; DOI: 10.35975/apic.v28i4.2400. Received: February 26, 2024; Reviewed: April 16, 2024; Accepted: July 09, 2024