Expressing the CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) Cystatin C Equations for Estimating GFR With Standardized Serum Cystatin C Values

Tufts Medical Center, Boston, Massachusetts.
American Journal of Kidney Diseases (Impact Factor: 5.76). 08/2011; 58(4):682-4. DOI: 10.1053/j.ajkd.2011.05.019
Source: PubMed
  • Source
    • "Fourth, in our study, a nephelometric assay was used to measure serum cystatin C concentration, while some other investigators have used colorimetric or turbidimetric assays. However, the standardization of serum cystatin C measurements is solved now and internationally accepted reference material is available [39] [40] [41]. Finally, the cause of kidney damage other than diabetes mellitus was not analyzed in our patients. "
    [Show abstract] [Hide abstract]
    ABSTRACT: In clinical practice the glomerular filtration rate (GFR) is estimated from serum creatinine-based equations like the Cockcroft-Gault formula (C&G) and Modification of Diet in Renal Disease formula (MDRD). Recently, serum cystatin C-based equations, the newer creatinine formula (The Chronic Kidney Disease Epidemiology Collaboration formula (CKD-EPI)), and equation that use both serum creatinine and cystatin C (CKD-EPI creatinine & cystatin formula) were proposed as new GFR markers. Present study compares serum creatinine-based equations, combined (including both serum creatinine and cystatin C) equation, and serum simple cystatin C formula (100/serum cystatin C) against 51CrEDTA clearance in 113 adult overweight Caucasians with diabetes mellitus type 2 (DM2) and chronic kidney disease (CKD). The results of present study demonstrated that the simple cystatin C formula could be a useful tool for the evaluation of renal function in overweight patients with DM2 and impaired kidney function in daily clinical practice in hospital and especially in outpatients. Despite the advantages of the simple cystatin C formula, cystatin C-based equations cannot completely replace the "gold standard" for estimation of the GFR in a population of DM2 patients with CKD, but may contribute to a more accurate selection of patients requiring such invasive and costly procedures.
    Experimental Diabetes Research 09/2012; 2012:179849. DOI:10.1155/2012/179849 · 3.54 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Serum levels of creatinine, cystatin C, or β trace protein allow estimation of GFR, but whether these markers contribute additional prognostic information beyond that reflected in GFR is unknown. Here, we analyzed data from the Modification of Diet in Renal Disease study, which provided baseline levels of these markers for 816 participants with a median follow-up of 16.6 years. We examined associations between the reciprocals of these filtration markers and (125)I iothalamate GFR, expressed per SD, with kidney failure and mortality. In univariate analysis, lower GFR and higher levels of each filtration marker associated with a higher risk for all outcomes. After adjustment for GFR in a Cox proportional hazards model, higher creatinine associated with a higher risk for kidney failure but a lower risk for all-cause mortality. Higher cystatin C and β trace protein associated with a higher risk for both kidney failure and all-cause mortality. In models including either cystatin C or β trace protein, the association of GFR with all-cause mortality was no longer significant after the addition of the filtration marker, suggesting the possibility of multicollinearity. In summary, after adjustment for GFR, levels of creatinine, cystatin C, and β trace protein, each remained directly associated with kidney failure but differed with respect to their associations with mortality. These differences may be a result of non-GFR-related associations of filtration markers, residual confounding by GFR, or collinearity between the filtration markers and GFR. β trace protein and cystatin C seem to provide more consistent prognostic information than creatinine.
    Journal of the American Society of Nephrology 12/2011; 23(2):351-9. DOI:10.1681/ASN.2011070663 · 9.47 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Serum cystatin C level has been shown to have a stronger association with clinical outcomes than serum creatinine level. However, little is known about the combined association of cystatin C-based estimated glomerular filtration rate (eGFR(cys)) and albuminuria with clinical outcomes, particularly at levels lower than current chronic kidney disease (CKD) cutoffs. Prospective cohort. 10,403 ARIC (Atherosclerosis Risk in Communities) Study participants followed up for a median of 10.2 years. eGFR(cys), albuminuria. Mortality, coronary heart disease (CHD), and heart failure, as well as a composite of any of these separate outcomes. Both decreased eGFR(cys) and albuminuria were associated independently with the composite outcome, as well as mortality, CHD, and heart failure. Although eGFR(cys) of 75-89 mL/min/1.73 m(2) in the absence of albuminuria (albumin-creatinine ratio [ACR] <10 mg/g) or albuminuria with ACR of 10-29 mg/g with normal eGFR(cys) (90-104 mL/min/1.73 m(2)) was not associated significantly with any outcome compared with eGFR(cys) of 90-104 mL/min/1.73 m(2) and ACR <10 mg/g, the risk of each outcome was significantly higher in those with both eGFR(cys) of 75-89 mL/min/1.73 m(2) and ACR of 10-29 mg/g (for mortality, HR of 1.4 [95% CI, 1.1-2.0]; for CHD, HR of 1.9 [95% CI, 1.4-2.6]; for heart failure, HR of 1.8 [95% CI, 1.2-2.7]). Combining the 2 markers improved risk classification for all outcomes (P < 0.001), even in those without overt CKD. Only one measurement of cystatin C. Mildly decreased eGFR(cys) and mild albuminuria independently contributed to the risk of mortality, CHD, and heart failure. Even minimally decreased eGFR(cys) (75-89 mL/min/1.73 m(2)) is associated with increased risk in the presence of mild albuminuria. Combining the 2 markers is useful for improved risk stratification even in those without clinical CKD.
    American Journal of Kidney Diseases 04/2012; 60(2):207-16. DOI:10.1053/j.ajkd.2012.03.011 · 5.76 Impact Factor
Show more