Background Elevated plasma
cystatin C levels reflect reduced renal function and increased cardiovascular risk. Less is known about whether the increased risk persists long-term or is independent of renal function and other important
biomarkers. Methods and Results
Cystatin C and other
biomarkers were measured at baseline (in 7863 patients) and 1 year later (in 6106 patients) in participants in the
LIPID (Long-Term Intervention with
Pravastatin in Ischemic Disease) study, who had a previous
acute coronary syndrome. Outcomes were ascertained during the study (median follow-up, 6 years) and long-term (median follow-up, 16 years). Glomerular filtration rate (GFR) was estimated using
Chronic Kidney Disease Epidemiology Collaboration equations (first GFR-
creatinine, then GFR-
creatinine-
cystatin C). Over 6 years, in fully adjusted multivariable time-to-event models, with respect to the primary end point of
coronary heart disease mortality or nonfatal
myocardial infarction, for comparison of Quartile 4 versus 1 of baseline
cystatin C, the hazard ratio was 1.37 (95% CI, 1.07-1.74; P=0.01), and for major cardiovascular events was 1.47 (95% CI, 1.19-1.82; P<0.001). Over 16 years, the association of baseline
cystatin C with
coronary heart disease, cardiovascular, and all-cause mortality persisted (each P<0.001) and remained significant after adjustment for estimated GFR-
creatinine-
cystatin C.
Cystatin C also predicted the development of
chronic kidney disease for 6 years (odds ratio, 6.61; 95% CI, 4.28-10.20) independently of estimated GFR-
creatinine and other risk factors. However, this association was no longer significant after adjustment for estimated GFR-
creatinine-
cystatin C. Conclusions
Cystatin C independently predicted major cardiovascular events, development of
chronic kidney disease, and cardiovascular and all-cause mortality. Prediction of long-term mortality was independent of improved estimation of GFR. Registration URL: https://anzctr.org.au; Unique identifier: ACTRN12616000535471.