Increased urinary cystatin C indicated higher risk of cardiovascular death in a community cohort.

OBJECTIVES Urinary cystatin C (u-CysC) is a new biomarker for acute tubular kidney dysfunction and may also indicate chronic tubular dysfunction. Chronic kidney disease is an important cardiovascular risk factor, however it is not known if u-CysC is a risk marker for cardiovascular death. METHODS The association between u-CysC and cardiovascular mortality was investigated in a Swedish community-based cohort of 604 men aged 78 years. During follow-up (mean 6.7 years), 203 participants died, of which 90 due to cardiovascular causes. RESULTS High u-CysC (>0.029 mg/mmol Cr) was associated with a more than 2-fold risk of cardiovascular death (multivariable hazard ratio for quintile 5 vs. 1: 2.5, 95% CI 1.2-5.2, P < 0.05) in Cox regression models independent of cardiovascular risk factors, glomerular filtration rate (eGFR) and urinary Albumin. Participants with low eGFR (≤60 mL/min), albuminuria (≥3 mg/mmol Cr) and high u-CysC (>0.029 mg/mmol Cr) combined had a significantly higher cardiovascular mortality risk compared to participants with one or two of these biomarkers normal (hazard ratio 15, 95% CI: 6.7-36, P < 0.001, compared to all three biomarkers normal). CONCLUSIONS This study is the first to show that increased concentrations of the tubular kidney biomarker u-CysC indicated risk of cardiovascular death independently of other cardiovascular risk factors, glomerular filtration and albuminuria. Additional research is needed to further establish the usefulness of u-CysC in clinical practice.