Cystatin C and creatinine as markers of bleeding complications, cardiovascular events and mortality during oral anticoagulant treatment.

BACKGROUND

Impaired kidney function has been linked to both ischemic events as well as bleeding complications in several clinical conditions. Our aim was to investigate if cystatin C, creatinine and calculated glomerular filtration rate (eGFR) were related to future risk of bleeding complications, cardiovascular events or all-cause mortality during oral anticoagulant treatment.

METHODS

In a cohort study, 719 patients on long-term vitamin K antagonist (VKA) treatment were followed for a mean of 4.2 years. Blood sampling was taken at inclusion and patients were followed prospectively. Cystatin C and creatinine were analysed and eGFR was calculated. All medical records were reviewed. Major bleeding events, myocardial infarctions, strokes, arterial emboli, and deaths were recorded and classified.

RESULTS

After adjustment for age, no association between cystatin C, creatinine or eGFR and major bleeding was found. Cystatin C was independently associated with cardiovascular events (hazard ratio 1.50 (95% CI: 1.27-1.77)) and all-cause mortality (hazard ratio 1.62 (95% CI: 1.38-1.90)).Creatinine was only associated with all-cause mortality, while eGFR was not associated with any of the outcomes.

CONCLUSIONS

Our findings underscore the superiority of cystatin C as a marker of cardiovascular risk compared to creatinine or eGFR. VKA-treated patients with increased cystatin C levels should be considered to be at an increased risk of cardiovascular events, and not bleeding complications.