Cystatin C identifies cardiovascular risk better than creatinine-based estimates of glomerular filtration in middle-aged individuals without a history of cardiovascular disease.

OBJECTIVES: Creatinine- and cystatin C-based estimates of renal function are considered to be cardiovascular disease (CVD) risk factors, but the clinical utility in middle-aged subjects without a history of CVD is controversial.
DESIGN: We related plasma cystatin C and creatinine-based glomerular filtration rate (GFR) [MDRD, CKD-EPI-2009, and CKD-EPI-comb (a combination of creatinine and cystatin C)] to incident CVD, CVD mortality, all-cause mortality, and heart failure in 4650 middle-aged subjects without CVD.
RESULTS: The hazard ratio (HR) per standard deviation increment (95% CI) of cystatin C predicted incident CVD (1.22, 1.11-1.33; P < 0.0001), CVD mortality (1.44, 1.24-1.66; P < 0.0001), all-cause mortality (1.15, 1.05-1.26; P = 0.002), and heart failure (1.27, 1.05-1.55; P = 0.02), whereas MDRD and CKD-EPI-2009 only predicted CVD mortality (0.79, 0.66-0.93; P = 0.006 and 0.78, 0.66-0.92; P = 0.003, respectively). Cystatin C led to a significant increase in the net reclassification improvement for all endpoints, except heart failure. Only within the quartile with the worst renal function were all measures related to all-cause and CVD mortality. The top 25% of cystatin C in the population significantly predicted risk of incident CVD and CVD mortality, whereas MDRD and CKD-EPI-2009 were predictors of CVD mortality only at a GFR < 60 mL/min/1.73 m(2) (11-13% of the population) and of incident CVD only at a GFR < 45 mL/min/1.73 m(2) (<1% of the population).
CONCLUSION: Cystatin C is a better risk marker for CVD morbidity and mortality than creatinine-based GFR. Whether this is explained by cystatin C being a better marker for true GFR or through other effects of cystatin C remains to be shown.