Disease Activity in Ankylosing Spondylitis and Associations to Markers of Vascular Pathology and Traditional Cardiovascular Disease Risk Factors: A Cross-sectional Study

Objective. To compare the risk of cardiovascular disease (CVD) in ankylosing spondylitis (AS) and population controls, and to examine the associations between disease activity and CVD risk. Methods. A cross-sectional study was done of patients with AS grouped according to Ankylosing Spondylitis Disease Activity Score (ASDAS) into ASDAS-high and ASDAS-low. Markers of vascular pathology, impaired endothelial function [asymmetric dimethylarginine (ADMA)], and arterial stiffness [augmentation index (AIx) and pulse wave velocity (PWV)], and traditional CVD risk factors [blood pressure, lipids, body mass index (BMI), CVD risk scores] were compared between AS and controls as well as across ASDAS-high versus ASDAS-low versus controls using ANCOVA analyses. Results. Altogether, 151 patients with AS and 134 controls participated. Patients had elevated ADMA (mu mol/l) and AIx (%) compared to controls: mean difference (95% CI): 0.05 (0.03, 0.07), p < 0.001 and 2.6 (0.8, 4.3), p = 0.01, respectively. AIx increased with higher ASDAS level, p(trend) < 0.04. There were no significant group differences of PWV. BMI was higher in ASDAS-high compared to ASDAS-low (p = 0.02). Total cholesterol was lower in AS compared to controls, and lower with higher ASDAS, p(trend) = 0.02. CVD risk scores were similar across groups except for Reynolds Risk Score, where the ASDAS-high group had a significantly higher score, compared to both ASDAS-low and controls. Conclusion. Elevated ADMA and AIx in AS support a higher CVD risk in AS. Elevated AIx and BMI in AS with high ASDAS indicate an association between disease activity and CVD risk. Lower total cholesterol in AS may contribute to underestimation of CVD risk.