Correlation between serum cystatin C and markers of subclinical atherosclerosis in hypertensive patients

BACKGROUND: Serum cystatin C (s-CC), an endogenous marker of kidney function, has also been proposed as a cardiovascular risk marker. However, it is unknown whether it is a direct marker of atherosclerosis, independently of kidney function. OBJECTIVE: The aim of this study was to correlate s-CC with two surrogate markers of subclinical atherosclerosis. METHODS: This is a cross-sectional study involving 103 middle-aged (57.49 ± 11.7 years) hypertensive outpatients, being 60 female (58.25%), most with preserved kidney function. S-CC was correlated with carotid intima media thickness (IMT) and flow-mediated dilation of brachial artery (FMD), both assessed by ultrasound, as well as with measured creatinine clearance and established cardiovascular risk factors. RESULTS: S-CC was neither significantly correlated with IMT (r = -0.024; p = 0.84) nor with FMD (r = -0.050 and p = 0.687) and no significant association was observed with conventional risk factors and inflammatory markers. In univariate analysis, s-CC was correlated with measured creatinine clearance (r = -0,498; p < 0,001), age (r = 0,408; p < 0,001), microalbuminuria (r = 0,291; p = 0,014), uric acid (r = 0,391; p < 0,001), ratio E/e' (r = 0,242; p = 0,049) and Framingham score (r = 0,359; p = 0,001). However, after multiple regression analysis, only the association with measured creatinine clearance remained significant (r = -0,491; p < 0,001). CONCLUSION: In middle-aged hypertensive outpatients, s-CC correlated with measured creatinine clearance, as expected, but no association was observed with markers of atherosclerosis neither with established cardiovascular risk factors.