Microalbuminuria, but not cystatin C, is associated with carotid atherosclerosis in middle-aged adults

Background. Cystatin C, a marker of renal function, has been shown to be an independent predictor of cardiovascular disease (CVD) in older adults, but few data are available in middle-aged adults. Moreover, no study has compared cystatin C and microalbuminuria as risk factors for CVD outcomes in middle-aged adults, and it is not known whether cystatin C is related to an early stage of atherosclerosis. Methods. We evaluated the relationships between serum creatinine, estimated glomerular filtration rate (GFR), serum cystatin C (all divided into tertiles), microalbuminuria and carotid atherosclerosis in a population-based random sample of 523 adults aged 35-64 years from the Seychelles (Indian Ocean). GFR was estimated using the modification of diet in renal disease (MDRD) equation. Intima-media thickness (IMT) was assessed by B-mode ultrasound. Results. The mean age of the study sample was 52 years, and 55% were women. Carotid IMT was higher in participants with microalbuminuria (802 vs 732 mu m, P < 0.001) and was inversely associated with GFR tertiles (from 728 to 809 mu m, P for trend = 0.002). IMT was not associated with cystatin C or creatinine (P for trend = 0.10 and 0.16, respectively). In multivariate analyses adjusted for cardiovascular risk factors, the association between microalbuminuria and IMT remained (P = 0.047), while the association between GFR and IMT disappeared (P for trend = 0.33). Conclusions. Microalbuminuria, but not cystatin C, is associated with carotid atherosclerosis beyond traditional cardiovascular risk factors among middle-aged adults. Cystatin C does not have a stronger relationship with carotid atherosclerosis in middle-aged adults than creatinine.