Serum cathepsin S and cystatin C: relationship to subclinical carotid atherosclerosis in rheumatoid arthritis

Objective To assess whether serum cathepsin S and cystatin C, two novel markers of cardiovascular disease risk, are associated with subclinical carotid atherosclerosis in patients with rheumatoid arthritis (RA). Methods Serum cystatin C and cathepsin S levels, carotid intima-media thickness (cIMT) and carotid plaques were assessed in a cross-sectional study involving 178 RA patients. Results An association between disease activity scores with higher levels of cystatin C, but not with cathepsin S, was found. Cystatin C levels were also associated with cIMT in the patient subgroup included in the higher quartile of cIMT (OR 1.31, 95%CI [1.00-1.72], p=0.04) after adjusting for traditional cardiovascular risk factors, age and sex. An association between serum cystatin C levels and carotid plaques was also found in the univariate analysis (OR 1.37, 95%CI [1.06-1.76], p=0.02). However, this significant association was lost after adjusting for traditional cardiovascular risk factors and age. Cathepsin S was not associated with cIMT or carotid plaques. Conclusion High cystatin C serum levels identify a subgroup of RA patients with a high risk of subclinical atherosclerotic disease.