Derivation and Validation of Cystatin C–Based Prediction Equations for GFR in Children

Zappitelli, Michael; Parvex, Paloma; Joseph, Lawrence; Paradis, Gilles; Grey, Vijaylaxmi; Lau, Susie; Bell, Lorraine

doi:10.1053/j.ajkd.2006.04.085

Cited by 257 publications

(212 citation statements)

References 51 publications

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“…Estimated GFR values were calculated using four Scr-based equations (Schwartz [20], Flanders Metadata [19], simple height-independent [21], Q(height) [22]), three CysC-based equations (Larsson [23], Filler [24], Zappitelli [25]) and two Scr/CysC-based equations (Zappitelli [25], Bouvet [26]). Only formulas based on enzymatic Scr and/or nephelometry were included.…”

Section: Estimated Gfr (Egfr)mentioning

confidence: 99%

Renal function in children and adolescents with Duchenne muscular dystrophy

Braat

Hoste

Waele

et al. 2015

Neuromuscular Disorders

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Improved life expectancy and the need for robust tools to monitor renal safety of emerging new therapies have fueled the interest in renal function in Duchenne muscular dystrophy (DMD) patients. We aimed to establish a methodology to accurately assess their renal function. Twenty DMD patients (5-22 years) were included in this prospective study. After obtaining medical history, all patients underwent a clinical examination, 24-hour ambulatory blood pressure monitoring, ultrasound of the kidneys, direct GFR measurement ( 51 Cr-EDTA, mGFR), complete blood and urine analysis. Seventeen of 20 patients were treated with corticosteroids and 5/20 with angiotensin converting enzyme inhibitor (lisinopril). No patient suffered from urinary tract infections or other renal diseases. Hypertension (systolic or diastolic blood pressure >P95) was found in 9/20 patients (8/9 patients were on steroid treatment) and a non-dipping blood pressure profile in 13/20 subjects (10/13 patients were on steroid treatment). Urinary protein to creatinine ratio was elevated in 17/18 patients, whereas 24-hour urine protein excretion was normal in all subjects. Median interquartile range (IQR) mGFR was 130.4 (29.1) mL/min/1.73 m 2 . Hyperfiltration (mGFR >150 mL/min/1.73 m 2 ) was found in 5/20 patients. Inverse correlation between mGFR and age was observed (R 2 = 0.45, p = 0.001). Serum creatinine based estimated GFR (eGFR) equations overestimated mGFR up to 300%. eGFR based on cystatin C Filler equation was closest to the mGFR (median eGFR (IQR) of 129.5 (39.7) mL/min/1.73 m 2 ). Our study demonstrates a high prevalence of hyperfiltration and hypertension in children and adolescents with DMD. Because the majority of hypertensive patients were under corticosteroid treatment, the iatrogenic cause of hypertension cannot be excluded. Serum or urine creatinine measurements are of no value to evaluate renal function in DMD patients due to the reduced skeletal muscle mass.

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Section: Estimated Gfr (Egfr)mentioning

confidence: 99%

Renal function in children and adolescents with Duchenne muscular dystrophy

Braat

Hoste

Waele

et al. 2015

Neuromuscular Disorders

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“…With different equations, the estimates of cystatin C eGFR also vary for the same cystatin C level (3,11,14). The equations performed differently in subsequent studies than in the original studies (11).…”

Section: Introductionmentioning

confidence: 99%

“…Various cystatin C equations consistently demonstrate a variance between the measured GFR and cystatin C estimated GFR (eGFR) in the magnitude of 20% to 30% (2,3,13). With different equations, the estimates of cystatin C eGFR also vary for the same cystatin C level (3,11,14).…”

Section: Introductionmentioning

confidence: 99%

“…Serum cystatin C is a relatively new endogenous marker that offers the advantage of a constant production by all nucleated body cells and its almost entire catabolism at the proximal tubule (1). In clinical studies, serum cystatin C has been found to be a good marker for predicting GFR (2)(3)(4)(5)(6)(7)(8)(9).…”

Section: Introductionmentioning

confidence: 99%

“…Various predictive equations have been established based on serum cystatin C levels (2)(3)(4)(5)(6)(7)(8). In children, the validated equations have used serum cystatin C levels either without serum creatinine (e.g., Bö kenkamp, Filler, Grubb, and Zapitelli-CysEq equations) (2)(3)(4)6) or with serum creatinine (e.g., Bouvet, chronic kidney disease in children [CKiD], and Zapitelli-CysCrEq equations) (3,8,11). The rationale of combining serum creatinine and plasma cystatin C originated from the fact that the sources of error for either marker differ.…”

Section: Introductionmentioning

confidence: 99%

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Diagnostic Accuracy of Cystatin C–Based eGFR Equations at Different GFR Levels in Children

Sharma

Yasin

Garg

et al. 2011

Clinical Journal of the American Society of Nephrology

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SummaryBackground and objectives The diagnostic accuracy of cystatin C estimated GFR (eGFR) by various cystatin C equations have varied in different studies. We hypothesized that the GFR level of enrolled patients affects the diagnostic accuracy of a cystatin C equation.Design, setting, participants, & measurements We analyzed 240 consecutively enrolled children at a single Canadian center in a prospective and cross-sectional study. Cystatin C was analyzed with nephelometry, and cystatin C eGFR was estimated by the equations validated in children. GFR was measured by technetium-99m-diethylene-triamine penta-acetic acid ( 99m Tc DTPA).Results We compared various cystatin C equations across GFR strata Ͻ60, Ͻ90, Ն135, and Ն150 ml/min per 1.73 m 2 for an accurate prediction and appropriate classification of the measured GFR. The CKiD, Zappitelli-CysEq, and Zappitelli-CysCrEq equations had a higher accuracy, estimated by eGFR values within 10% and 30% of the respective 99m Tc DTPA, in the GFR categories Ͻ60 and Ͻ90 ml/min per 1.73 m 2 , whereas the Bö kenkamp, Bouvet, and Filler equations had a greater accuracy in the GFR categories Ն135 and Ն150 ml/min per 1.73 m 2 . The Bouvet, CKiD, Filler, Zappitelli-CysEq, and Zappitelli-CysCrEq equations had a greater sensitivity to classify GFR Ͻ60 and Ͻ90 ml/min per 1.73 m 2 , whereas the Bö kenkamp equation had a higher sensitivity for GFR Ն135 and Ն150 ml/min per 1.73 m 2 . ConclusionsThe diagnostic accuracy of various cystatin C equations varies with GFR. This issue needs consideration while applying these equations in clinical practice and for further research on eGFR equations.

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