Background Antiphospholipid syndrome (APS) may carry a worse prognosis for vascular complications when co-existing with subclinical atherosclerosis, however, the association between the two conditions remains ambiguous.

Methods We evaluated ultrasonographic markers of subclinical atherosclerosis in carotid and femoral arteries of 86 patients with thrombotic APS (43 primary APS (PAPS), 43 systemic lupus erythematosus-associated APS [SLE/APS]), 86 patients with diabetes mellitus (DM) and 86 healthy controls, individually matched for age and gender, and investigated their associations with traditional and disease-related factors in APS.

Results Carotid plaques were found in 28% of PAPS, 23% of SLE/APS, and 30% of DM patients versus 9% of controls (p=0.006). Femoral plaques were found in 33% of PAPS, 19% of SLE/APS, 20% of DM, and 9% of controls (p=0.032). Multivariate regression-derived relative risk estimates for atherosclerotic plaques in any location were 2.72 for PAPS, 2.63 for SLE/APS, and 1.98 for DM (p=0.004, 0.009, 0.032 respectively), after adjusting for age, gender, hypertension, dyslipidemia, smoking, BMI, and family history of coronary disease. Among patients with APS, atherosclerotic plaques were associated with the number of traditional CVD risk factors in both PAPS (RR=2.75, p<0.001) and SLE/APS (RR=1.84, p<0.001), and with IgG anti-beta2-glycoprotein I antibodies in SLE/APS.

Conclusions Patients with PAPS and SLE/APS have a nearly 2.5-fold risk of atherosclerotic plaques in carotid and femoral arteries compared to healthy controls, similar to DM patients. Atherosclerotic plaques are associated with the number of traditional risk factors in both APS and SLE/APS, and with IgG anti-beta2-glycoprotein I antibodies in SLE/APS.