title: Cystatin C- and creatinine-based estimates of renal function and their value for risk prediction in patients with acute coronary syndrome: results from the PLATelet Inhibition and Patient Outcomes (PLATO) study.
abstract: BACKGROUND
  The estimated glomerular filtration rate (eGFR) independently predicts cardiovascular death or myocardial infarction (MI) and can be estimated by creatinine and cystatin C concentrations. We evaluated 2 different cystatin C assays, alone or combined with creatinine, in patients with acute coronary syndrome.
  
  
  METHODS
  We analyzed plasma cystatin C, measured with assays from Gentian and Roche, and serum creatinine in 16 279 patients from the PLATelet Inhibition and Patient Outcomes (PLATO) trial. We evaluated Pearson correlation and agreement (Bland-Altman) between methods, as well as prognostic value in relation to cardiovascular death or MI during 1 year of follow up by multivariable logistic regression analysis including clinical variables, biomarkers, c-statistics, and relative integrated discrimination improvement (IDI).
  
  
  RESULTS
  Median cystatin C concentrations (interquartile intervals) were 0.83 (0.68-1.01) mg/L (Gentian) and 0.94 (0.80-1.14) mg/L (Roche). Overall correlation was 0.86 (95% CI 0.85-0.86). The level of agreement was within 0.39 mg/L (2 SD) (n = 16 279). The areas under the curve (AUCs) in the multivariable risk prediction model with cystatin C (Gentian, Roche) or Chronic Kidney Disease Epidemiology Collaboration eGFR (CKD-EPI) added were 0.6914, 0.6913, and 0.6932. Corresponding relative IDI values were 2.96%, 3.86%, and 4.68% (n = 13 050). Addition of eGFR by the combined creatinine-cystatin C equation yielded AUCs of 0.6923 (Gentian) and 0.6924 (Roche) with relative IDI values of 3.54% and 3.24%.
  
  
  CONCLUSIONS
  Despite differences in cystatin C concentrations, overall correlation between the Gentian and Roche assays was good, while agreement was moderate. The combined creatinine-cystatin C equation did not outperform risk prediction by CKD-EPI.
authors.affiliation: Department of Medical Sciences, Cardiology, Uppsala University, Uppsala Sweden. axel.akerblom@ucr.uu.se
authors.forename: Axel
authors.initials: A
authors.lastname: Åkerblom
authors.forename: Lars
authors.initials: L
authors.lastname: Wallentin
authors.forename: Anders
authors.initials: A
authors.lastname: Larsson
authors.forename: Agneta
authors.initials: A
authors.lastname: Siegbahn
authors.forename: Richard C
authors.initials: RC
authors.lastname: Becker
authors.forename: Andrzej
authors.initials: A
authors.lastname: Budaj
authors.forename: Anders
authors.initials: A
authors.lastname: Himmelmann
authors.forename: Jay
authors.initials: J
authors.lastname: Horrow
authors.forename: Steen
authors.initials: S
authors.lastname: Husted
authors.forename: Robert F
authors.initials: RF
authors.lastname: Storey
authors.forename: Nils
authors.initials: N
authors.lastname: Asenblad
authors.forename: Stefan K
authors.initials: SK
authors.lastname: James
mesh_terms: D054058:Acute Coronary Syndrome / Q000097:blood* / Q000175:diagnosis* / Q000453:epidemiology; D003404:Creatinine / Q000097:blood*; D055316:Cystatin C / Q000097:blood*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D015233:Models, Statistical; D011379:Prognosis; D012307:Risk Factors
chemical_list: D055316:Cystatin C; D003404:Creatinine