A study of carotid intima media thickness in patients with rheumatoid arthritis and its correlation with acute phase reactants and disease activity

Introduction: There is increased risk of cardiovascular morbidity and mortality in patients of rheumatoid arthritis (RA) due to accelerated atherosclerosis. In this study we measured Carotid artery intima media thickness (CIMT) as a surrogate marker for subclinical atherosclerosis in RA patients without pre-existing cardiovascular disease. This study also analyzed the correlation between CIMT, disease duration, Simplified Disease Activity Index (SDAI) and acute phase reactants.
Methods: A cross-sectional study was conducted on 90 patients divided into two groups of 45 patients of RA and another 45 control subjects. Subjects with RA and age and sex matched healthy controls were included in the study without pre-existing CV risk factors. Complete clinical evaluation, hematological and biochemical profile done. ESR, CRP and platelet count were used as markers of acute phase reactants. All the RA patients included in the study were evaluated for their disease activity using Simplified Disease Activity Index (SDAI). All the subjects including the controls evaluated for carotid intima media thickness by using carotid ultrasonography. CIMT measured in common carotid artery bilaterally by examining throughout common carotid artery up to 2 cm proximal to bifurcation. CIMT measurement taken at the site of greatest thickness. All measurements taken in diastole, measured in phase when lumen diameter is at its smallest and IMT at its largest. Mean value of 6 readings (3 from each side) taken as final CIMT for evaluation. B mode (linear probe) USG was used to determine carotid IMT.
Results: 45 cases and similar control subjects included in the study with mean age (SD) as 45.07 (14.81) years. We found female preponderance with 37 females out of 45 cases. Mean (SD) disease duration in male subjects was 5.38(2.40) years while in females was 5.09 (2.78) years. CRP was found to be significantly increased in cases group with mean (SD) of 5.75(8.85) mg/dl. ESR significantly raised to 35.22(13.55) mm/hour in cases group compared to control group where it was 16.16(5.71) mm/hr. Mean (SD) platelets (x10³/mm³) were 229.24(69.80) in cases while controls had 290.33(83.85), so platelets correlation with disease could not be established. CIMT was significantly raised in cases group. Mean (SD) CIMT in cases was 0.95(1.06) mm whereas in control group it was 0.60(0.16) mm with p value of 0.002. Moderate positive correlation was found between CIMT (mm) and SDAI and this correlation was statistically significant with p=0.001. For every 1 unit increase in CIMT, the SDAI increases by 2.92 units. A strong positive correlation between CIMT (mm) and Disease Duration (Years), and this correlation was statistically significant (rho = 0.9, p = <0.001). For every 1 unit increase in CIMT (mm), the Disease Duration (Years) increases by 1.26 units. Conversely, for every 1 unit increase in Disease Duration (Years), the CIMT (mm) increases by 0.19 units.
Conclusion: A strong correlation was observed between CIMT and disease duration in rheumatoid arthritis. Hence, CIMT can be a useful surrogate marker for detecting atherosclerosis in patients with RA. In view of the relation to duration of disease, established RA patients should regularly be screened to identify the evidence of atherosclerosis and manage it earlier. Prevention of cardiovascular disease in RA requires an integrated approach encompassing cardiovascular risk factors screening and management, effective and sustained control of RA disease activity, high index of suspicion and prompt investigation of suspected cardiac disease.