Accuracy of Different Equations in Estimating GFR in Pediatric Kidney Transplant Recipients

Abstract

Background and objective The knowledge of renal function is crucial for the management of pediatric kidney transplant recipients. In this population, the most commonly used plasma creatinine (PCr)-based or cystatin C (CystC)-based GFR-predicting formulas may underperform (e.g., corticosteroids and trimethoprim may affect PCr concentration, whereas prednisone and calcineurin inhibitors may affect CystC concentration). This study evaluated the performance of six formulas in pediatric kidney transplant recipients.Design, setting, participants, & measurements The study used PCr-based formulas (bedside Schwartz, SchwartzLyon), CystC-based formulas (Hoek, Filler), and combined PCr-CystC-based formulas (CKD in Children [CKiD] 2012 and Zappitelli). The performance of these formulas was compared using inulin clearance as reference and assessed according to CKD stages in a historical cohort that included 73 pediatric kidney transplant recipients (199 measurements). The ability of the formulas to identify GFRs,60, ,75, and ,90 ml/min per 1.73 m 2 was assessed.Results At measured GFR (mGFR) $90 ml/min per 1.73 m 2 (nine patients; 23 measurements), the Zappitelli formula had the highest 30% accuracy (P30) (95% [95% confidence interval (95% CI), 87% to 100%]) and the bedside Schwartz had the highest 10% accuracy (P10) (56% [95% CI, 32% to 72%]). At mGFR$60 and ,90 ml/min per 1.73 m 2 (22 patients; 91 measurements), all formulas had P30 values .80%. However, only the CKiD 2012 formula had a P10 value .50%. At mGFR,60 ml/min per 1.73 m 2 (42 patients; 85 measurements), the CKiD 2012 and Schwartz-Lyon formulas had the highest P10 (45% [95% CI, 34% to 55%] and 43% [95% CI, 33% to 54%]) and P30 (90% [95% CI, 84% to 97%] and 91% [95% CI, 86% to 98%]). All studied equations except Hoek and Filler had areas under the receiver-operating characteristic curves significantly .90% in discriminating patients with renal dysfunction at various CKD stages (GFR,60, ,75, and ,90 ml/min per 1.73 m 2 ).Conclusions In pediatric kidney transplant recipients, the CKiD 2012 formula had the best performance at mGFRs,90 ml/min per 1.73 m 2 . CystC-based formulas were not superior to PCr-based formulas.

Fibroblast growth factor‐23 and chronic allograft injury in pediatric renal transplant recipients: a Midwest Pediatric Nephrology Consortium study

“…Secondary exposures included plasma FGF23 levels modeled as a categorical variable, plasma DKK1, sclerostin, soluble klotho, and activin‐A levels. Additional secondary exposures included a history of biopsy‐proven acute cellular or antibody‐mediated rejection (>6 months prior to enrollment), donor type (LD) or (DD), eGFR (CKD‐EPI calculation, traditional and CKD‐Schwartz calculations) , transplant vintage (years from transplantation to enrollment), current prednisone use (at enrollment), current calcitriol use (at enrollment), systolic/diastolic blood pressure, hypertension (blood pressure > 95th percentile for age/sex/height or taking antihypertensive medication), plasma calcium, and plasma phosphorus.…”

Renal function after combined liver‐kidney transplantation: A longitudinal study of pediatric and adult patients

“…However, both CKD‐EPI and MDRD equations have been pointed out as useful in solid organ transplantation population . In pediatric KT patients, bedside Schwartz equation has shown to overestimate mGFR based on a renal inulin clearance albeit providing acceptable 30% accuracy even in lower mGFR levels . However, since mGFRs were taken routinely in our pediatric patients, the choice to use one estimation equation over another is less important one.…”

“…In pediatric KT patients, bedsideSchwartz equation has shown to overestimate mGFR based on a renal inulin clearance albeit providing acceptable 30% accuracy even in lower mGFR levels 34. However, since mGFRs were taken routinely in our pediatric patients, the choice to use one estimation equation over another is less important one.Mean or median is shown for continuous variables to simplify comparison between current study and two other studies (references 15 and 16).…”

Validation of serum creatinine-based formulae in pediatric renal transplant recipients

“…Although these studies strengthen the clinical utility of using the eGFR equation for both CKD and non-CKD patients, they did not address a large number of transplant recipients. De Souza and colleagues have recently evaluated and compared the performance of SCr-based formulae (mod-Schwartz and Schwartz-Lyon) along with cystatin C-based (Hoek and Filler) and combined SCr-cystatin C-based formulae (CKiD 2012 and Zappitelli) in pediatric renal transplant recipients, however, they did not tackle the possible variation by age, gender, and clinical characteristics, which all may influence GFR (17). In addition, two other heightindependent formulae, Zappitelli and Pottel, were recently validated (18,19).…”

“…There is emerging evidence demonstrating that estimating GFR using serum cystatin C-based equations correlate better than SCr-based formulae in adults and children (20)(21)(22)(23)(24)(25). Studies to date indicate a modest agreement of the mod-Schwartz and measured GFR (10,12,13,17,26), and measurement of serum cystatin C is not widely available, limiting the routine clinical use; thus, our goal was to confirm that the mod-Schwartz formula is a valid bedside SCr-based formula to estimate GFR in larger populations of kidney transplant recipients and across a range of demographic and clinical characteristics.…”