Serum cystatin C levels are associated with coronary artery calcification in women without chronic kidney disease

Background Chronic renal disease (CKD) is a determinant of coronary artery calcification (CAC), which is a predictor of cardiovascular events. However, in a population without CKD, the association between CAC and renal function is unclear. CAC is affected by sex. This study aimed to determine whether serum cystatin C, a sensitive marker of kidney function, or sex differences are associated with CAC in patients without CKD. Methods We evaluated 456 consecutive patients (61 ± 13 years, 42% women) without CKD and evidence of coronary artery disease. The CAC (Agatston) score was examined by multidetector computed tomography. Results When patients were categorized into three CAC groups based on the Agatston score, mild (<10), moderate (11–399), and severe (≥400) in each sex, serum cystatin C levels gradually increased by severity of CAC in women, but not men. Receiver operating characteristic curve analysis showed that, in women, a cut-off value of 0.97 mg/l for cystatin C discriminated patients with severe CAC with a sensitivity of 71% and specificity of 77% (area under the curve, 0.74; 95% CI: 0.62–0.86; p < 0.01). Multivariate logistic analysis showed that serum cystatin C was not associated with severe CAC in all patients and men, but this association was observed in women (OR: 7.80 for cystatin C ≥ 0.97 mg/l, 95% CI: 1.76–34.6, p < 0.01). Conclusion Higher serum cystatin C levels are associated with greater CAC in women without CKD. Measurement of cystatin C may be useful for identifying women who are at high risk for cardiovascular disease.