TY - JOUR
T1 - Relationships of Measured Iohexol GFR and Estimated GFR With CKD-Related Biomarkers in Children and Adolescents
AU - Ng, Derek K.
AU - Schwartz, George J.
AU - Warady, Bradley A.
AU - Furth, Susan L.
AU - Muñoz, Alvaro
N1 - Funding Information:
Support: The CKiD Study is supported by grants from the National Institute of Diabetes and Digestive and Kidney Diseases, with additional funding from the Eunice Kennedy Shriver National Institute of Child Health and Human Development and the National Heart, Lung, and Blood Institute (U01-DK-66143, U01-DK-66174, U01-DK-082194, and U01-DK-66116).
Publisher Copyright:
© 2017 National Kidney Foundation, Inc.
PY - 2017/9
Y1 - 2017/9
N2 - Background 2 valid and reliable estimated glomerular filtration rate (GFR) equations for the pediatric population have been developed from directly measured GFR data in the Chronic Kidney Disease in Children (CKiD) cohort: the full CKiD and bedside CKiD equations. Although adult GFR estimating equations replicate relationships of measured GFR with biomarkers, it is unclear whether similar patterns exist among children and adolescents with chronic kidney disease (CKD). Study Design Prospective cohort study in children and adolescents. Settings & Participants 730 participants contributed 1,539 study visits. Predictors Measured GFR by plasma iohexol disappearance (mGFR), estimated GFR by the full CKiD equation (eGFRCKiDfull; based on serum creatinine, cystatin C, serum urea nitrogen, height, and sex), and estimated GFR by the bedside CKiD equation (eGFRCKiDbed; calculated as 41.3 × height [m]/serum creatinine [mg/dL]) were predictors of CKD-related biomarkers. Deviations of mGFR from eGFRCKiDfull and deviations of eGFRCKiDfull from eGFRCKiDbed from linear regressions (ie, residuals) were included in bivariate analyses. Outcomes & Measurements: CKD-related biomarkers included values for urine protein-creatinine ratio, blood hemoglobin, serum phosphate, bicarbonate, potassium, systolic and diastolic blood pressure z scores, and height z scores. Results The median age of 730 participants with CKD was 12.5 years, with median mGFR, eGFRCKiDfull, and eGFRCKiDbed of 51.8, 54.0, and 53.2 mL/min/1.73 m2, respectively. eGFRCKiDfull demonstrated as strong or stronger associations with CKD-related biomarkers than mGFR; eGFRCKiDbed associations were significantly attenuated (ie, closer to the null). Residual information in mGFR did not substantially increase explained variability. eGFRCKiDbed estimated faster GFR decline relative to mGFR and eGFRCKiDfull. Limitations Simple linear summaries of biomarkers may not capture nonlinear associations. Conclusions eGFRCKiDfull closely approximated mGFR to describe relationships with CKD-severity indicators and progression in this pediatric CKD population. eGFRCKiDbed offered similar inferences, but associations were attenuated and rate of progression was overestimated. The eGFRCKiDfull equation from 2012 is preferred for pediatric research purposes.
AB - Background 2 valid and reliable estimated glomerular filtration rate (GFR) equations for the pediatric population have been developed from directly measured GFR data in the Chronic Kidney Disease in Children (CKiD) cohort: the full CKiD and bedside CKiD equations. Although adult GFR estimating equations replicate relationships of measured GFR with biomarkers, it is unclear whether similar patterns exist among children and adolescents with chronic kidney disease (CKD). Study Design Prospective cohort study in children and adolescents. Settings & Participants 730 participants contributed 1,539 study visits. Predictors Measured GFR by plasma iohexol disappearance (mGFR), estimated GFR by the full CKiD equation (eGFRCKiDfull; based on serum creatinine, cystatin C, serum urea nitrogen, height, and sex), and estimated GFR by the bedside CKiD equation (eGFRCKiDbed; calculated as 41.3 × height [m]/serum creatinine [mg/dL]) were predictors of CKD-related biomarkers. Deviations of mGFR from eGFRCKiDfull and deviations of eGFRCKiDfull from eGFRCKiDbed from linear regressions (ie, residuals) were included in bivariate analyses. Outcomes & Measurements: CKD-related biomarkers included values for urine protein-creatinine ratio, blood hemoglobin, serum phosphate, bicarbonate, potassium, systolic and diastolic blood pressure z scores, and height z scores. Results The median age of 730 participants with CKD was 12.5 years, with median mGFR, eGFRCKiDfull, and eGFRCKiDbed of 51.8, 54.0, and 53.2 mL/min/1.73 m2, respectively. eGFRCKiDfull demonstrated as strong or stronger associations with CKD-related biomarkers than mGFR; eGFRCKiDbed associations were significantly attenuated (ie, closer to the null). Residual information in mGFR did not substantially increase explained variability. eGFRCKiDbed estimated faster GFR decline relative to mGFR and eGFRCKiDfull. Limitations Simple linear summaries of biomarkers may not capture nonlinear associations. Conclusions eGFRCKiDfull closely approximated mGFR to describe relationships with CKD-severity indicators and progression in this pediatric CKD population. eGFRCKiDbed offered similar inferences, but associations were attenuated and rate of progression was overestimated. The eGFRCKiDfull equation from 2012 is preferred for pediatric research purposes.
KW - CKD biomarker
KW - Chronic Kidney Disease in Children (CKiD)
KW - GFR estimating equation
KW - Pediatric
KW - adolescents
KW - children
KW - chronic kidney disease (CKD)
KW - estimated GFR
KW - glomerular filtration rate (GFR)
KW - iohexol
KW - kidney function
KW - kidney measure
KW - measured GFR
UR - http://www.scopus.com/inward/record.url?scp=85019544025&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85019544025&partnerID=8YFLogxK
U2 - 10.1053/j.ajkd.2017.03.019
DO - 10.1053/j.ajkd.2017.03.019
M3 - Article
C2 - 28549535
AN - SCOPUS:85019544025
SN - 0272-6386
VL - 70
SP - 397
EP - 405
JO - American Journal of Kidney Diseases
JF - American Journal of Kidney Diseases
IS - 3
ER -