Abstract: SA-PO408

Creatinine versus Cystatin C: Is There Any Benefit in Using a Cystatin C Based Equation for Assessment of CKD in Older Adults?

Session Information

Category: Chronic Kidney Disease (Non-Dialysis)

  • 302 CKD: Estimating Equations, Incidence, Prevalence, Special Populations

Authors

  • Zonoozi, Shahrzad, University College London, London, United Kingdom
  • Ramsay, Sheena E, Newcastle University, Newcastle Upon Tyne, United Kingdom
  • Papacosta, Olia, University College London, London, United Kingdom
  • Whincup, Peter, SGUL, London, United Kingdom
  • Wannamethee, Sasiwarang G., University College London, London, United Kingdom
Background

Chronic kidney disease (CKD) is associated with excess cardiovascular disease (CVD) mortality and morbidity. CKD diagnosis relies on calculation of the estimated glomerular filtration rate (eGFR) commonly based on serum creatinine which may lead to inaccurate estimations of GFR in the older population. Cystatin C is an alternative GFR marker less influenced by exogenous factors and the CKD Epidemiology Collaboration (CKD-EPI) has developed an equation for estimating GFR using this marker (CKD-EPICys). Whether this is a better indicator of CVD risk and mortality in older adults than the CKD-EPI creatinine-based equation (CKD-EPICr) is unclear. We have investigated the association between CKD classification, using CKD-EPICr and CKD-EPICys, and cardiovascular risk markers and CVD mortality in older adults.

Methods

Prospective and cross-sectional analysis of 1722 men aged 71-92 examined in 2010-2012 across 24 British towns, from the British Regional Heart Study initiated in 1978-1980, followed up for a median of 5 years for CVD and all-cause mortality. Participants completed a questionnaire, underwent a physical examination and had blood samples taken.

Results

The prevalence of CKD stages 1, 4 and 5 was increased in our population using CKD-EPICys versus CKD-EPICr to calculate eGFR. Both CKD equations were significantly associated with markers of inflammation (C-reactive protein), endothelial function (von Willebrand factor) and cardiac function (N-terminal pro brain natriuretic peptide). The hazard ratio (HR) for all CVD mortality in those with CKD stages 4 and 5 versus those with CKD stages 1 and 2 was 3.05 (95% CI, 1.63-5.70) and 3.62 (95% CI, 2.08-6.30) using CKD-EPICr and CKD-EPICys respectively. For all-cause mortality the HR was 2.30 (95% CI, 1.60-3.32) and 2.57 (95% CI, 1.87-3.54) using CKD-EPICr and CKD-EPICys respectively.

Conclusion

Estimating GFR using CKD-EPICys leads to reclassification of CKD staging and increased prevalence of CKD stages 1, 4 and 5 compared to CKD-EPICr. Our study shows that compared to CKD-EPICr, CKD-EPICys shows no improvement in the prediction of all-cause and CVD mortality in older British men. In view of the drive to use cystatin-c based equations in clinical practice, this may have important cost implications.

Funding

  • Private Foundation Support