Association of Atherogenic Indices With Disease Activity in Rheumatoid Arthritis Patients: A Cross-Sectional Study

Background: Rheumatoid arthritis (RA) is a chronic autoimmune inflammatory disorder associated with accelerated atherosclerosis and increased cardiovascular morbidity. Atherogenic indices derived from routine lipid parameters have emerged as potential markers of cardiovascular risk; however, their relationship with disease activity in RA remains incompletely understood, particularly in Indian populations. Objective: To evaluate the association between atherogenic indices and disease activity in patients with rheumatoid arthritis and to assess their potential utility as biomarkers of inflammatory burden and cardiometabolic risk. Methodology: This cross-sectional observational study included 100 patients with rheumatoid arthritis (RA) who met the 2010 American College of Rheumatology/European League Against Rheumatism (ACR/EULAR) classification criteria and 50 years of age- and sex-frequency-matched control participants without rheumatoid arthritis or other inflammatory rheumatic diseases. Clinical, anthropometric, laboratory, and lipid profile data were collected. Disease activity was assessed using the Disease Activity Score in 28 joints with C-reactive protein (DAS28-CRP). Atherogenic indices, including Castelli's Risk Index-I (CRI-I), Castelli's Risk Index-II (CRI-II), Atherogenic Index of Plasma (AIP), Atherogenic Coefficient (AC), and non-high-density lipoprotein cholesterol (non-HDL-C), were calculated and analyzed in relation to disease activity measures. Results: Patients with RA exhibited significantly higher triglycerides, low-density lipoprotein cholesterol (LDL-C), very low-density lipoprotein cholesterol (VLDL-C), non-high-density lipoprotein cholesterol (non-HDL-C), Castelli's Risk Index-I (CRI-I), Castelli's Risk Index-II (CRI-II), Atherogenic Index of Plasma (AIP), and Atherogenic Coefficient (AC), together with lower HDL-C levels compared with healthy controls (all p<0.05). Atherogenic indices increased progressively across disease activity categories, with the highest values observed among patients with high disease activity (all p≤0.001). Among the evaluated indices, AIP demonstrated the strongest correlation with Disease Activity Score in 28 joints with C-reactive protein (DAS28-CRP) (r=0.45, p<0.001), followed by CRI-II (r=0.38, p<0.001). In multivariable logistic regression analysis, AIP remained independently associated with high disease activity (odds ratio (OR)=3.12, 95% CI: 1.42-6.85, p=0.004), together with erythrocyte sedimentation rate (ESR) and BMI. Conclusions: Atherogenic indices are significantly associated with disease activity in rheumatoid arthritis, with AIP demonstrating the strongest relationship with inflammatory burden. These findings suggest that AIP may serve as a simple, inexpensive, and readily available marker for the integrated assessment of disease activity and cardiometabolic risk in patients with RA. Prospective multicenter studies are warranted to validate its clinical utility and prognostic significance.