Estimation of the glomerular filtration rate in children and young adults by means of the CKD-EPI equation with age-adjusted creatinine values

Abstract

The CKD-EPI creatinine-based estimation equation for glomerular filtration rate (GFR) cannot be used in children, overestimates GFR in young adults, and its combination with the KDIGO recommended pediatric CKiD (Schwartz bedside) equation causes implausible increases in estimated GFR when switching from pediatric to adult care. By establishing sex-specific creatinine growth curves for children and young adults, creatinine levels of children and young adults below age 40 years were adjusted with 40 as assigned age and applied in the CKD-EPI equation. Validation was performed in 4005 children (2–17 years) and 3309 young adults (18–39 years) using metrics based on bias, precision, and accuracy including percentage of estimates within 30% (P30) of measured GFR (mGFR). Comparisons were made with the CKiD and Schwartz-Lyon equations in children. CKD-EPI with age-adjusted creatinine instead of actual age and creatinine led to extensive improvements in bias, precision, and accuracy at all ages, in both sexes and at all levels of mGFR. At mGFR below and above 75 mL/min/1.73m2, the P30 increased from 12% to 75% and 33% to 88% in children, respectively, and from 56% to 73% and 83% to 92% in young adults, respectively. In children adjusted CKD-EPI was more accurate than CKiD, especially above mGFR 75 mL/min/1.73m2 (P30 88% vs. 82%), while Schwartz-Lyon was more accurate than adjusted CKD-EPI at mGFR below 75 mL/min/1.73m2 (P30 81% vs. 75%). Thus, the proposed strategy based on age-adjusted creatinine in children and young adults makes the CKD-EPI equation applicable across the full spectrum of age and kidney function. The CKD-EPI creatinine-based estimation equation for glomerular filtration rate (GFR) cannot be used in children, overestimates GFR in young adults, and its combination with the KDIGO recommended pediatric CKiD (Schwartz bedside) equation causes implausible increases in estimated GFR when switching from pediatric to adult care. By establishing sex-specific creatinine growth curves for children and young adults, creatinine levels of children and young adults below age 40 years were adjusted with 40 as assigned age and applied in the CKD-EPI equation. Validation was performed in 4005 children (2–17 years) and 3309 young adults (18–39 years) using metrics based on bias, precision, and accuracy including percentage of estimates within 30% (P30) of measured GFR (mGFR). Comparisons were made with the CKiD and Schwartz-Lyon equations in children. CKD-EPI with age-adjusted creatinine instead of actual age and creatinine led to extensive improvements in bias, precision, and accuracy at all ages, in both sexes and at all levels of mGFR. At mGFR below and above 75 mL/min/1.73m2, the P30 increased from 12% to 75% and 33% to 88% in children, respectively, and from 56% to 73% and 83% to 92% in young adults, respectively. In children adjusted CKD-EPI was more accurate than CKiD, especially above mGFR 75 mL/min/1.73m2 (P30 88% vs. 82%), while Schwartz-Lyon was more accurate than adjusted CKD-EPI at mGFR below 75 mL/min/1.73m2 (P30 81% vs. 75%). Thus, the proposed strategy based on age-adjusted creatinine in children and young adults makes the CKD-EPI equation applicable across the full spectrum of age and kidney function. The Kidney Disease: Improving Global Outcomes guideline1Kidney Disease: Improving Global Outcomes (KDIGO) CKD Work GroupKDIGO 2012 clinical practice guideline for the evaluation and management of chronic kidney disease.Kidney Int Suppl. 2013; 3: 1-150Abstract Full Text Full Text PDF Scopus (1298) Google Scholar recommends the creatinine based Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation2Levey A.S. Stevens L.A. Schmid C.H. et al.A new equation to estimate glomerular filtration rate.Ann Intern Med. 2009; 150: 604-612Crossref PubMed Scopus (13710) Google Scholar and the Chronic Kidney Disease in Children Study (CKiD, “Schwartz bedside”) equation3Schwartz G.J. Munoz A. Schneider M.F. et al.New equations to estimate GFR in children with CKD.J Am Soc Nephrol. 2009; 20: 629-637Crossref PubMed Scopus (2110) Google Scholar for estimation of glomerular filtration rate (eGFR) in adults and children, respectively. Their use in clinical practice is now widespread but they have some drawbacks. Flawed increases in renal function have been observed when switching from the height-dependent CKiD in pediatric care to the age-dependent CKD-EPI in adults.4Pottel H. Björk J. Bökenkamp A. et al.Estimating glomerular filtration rate at the transition from pediatric to adult care.Kidney Int. 2019; 95: 1234-1243Abstract Full Text Full Text PDF PubMed Scopus (15) Google Scholar Lack of height data in connection with creatinine analyses precludes automatic laboratory reporting of eGFR based on CKiD. In addition, the use of CKD-EPI is questionable in young adults owing to poor accuracy.5Nyman U. Grubb A. Larsson A. et al.The revised Lund-Malmö GFR estimating equation outperforms MDRD and CKD-EPI across GFR, age and BMI intervals in a large Swedish population.Clin Chem Lab Med. 2014; 52: 815-824Crossref PubMed Scopus (97) Google Scholar, 6Selistre L. de Souza V. Cochat P. et al.GFR estimation in adolescents and young adults.J Am Soc Nephrol. 2012; 23: 989-996Crossref PubMed Scopus (64) Google Scholar, 7Selistre L. Rabilloud M. Cochat P. et al.Comparison of the Schwartz and CKD-EPI equations for estimating glomerular filtration rate in children, adolescents, and adults: a retrospective cross-sectional study.PLoS Med. 2016; 13e1001979Crossref PubMed Scopus (36) Google Scholar, 8Björk J. Nyman U. Courbebaisse M. et al.Prospects for improved GFR estimation based on creatinine—results from a transnational multicentre study.Clin Kidney J. 2020; 13: 674-683Crossref PubMed Google Scholar Thus, there is a need for further development in the area of GFR estimation to extend the applicability of existing equations across the entire lifespan. We recently demonstrated how creatinine growth curves can be used to recalculate (adjust) childhood levels of serum creatinine to corresponding adult levels.9Björk J. Nyman U. Delanaye P. et al.A novel method for creatinine adjustment makes the revised Lund-Malmö GFR equation applicable in children.Scand J Clin Lab Invest. 2020; 80: 456-463Crossref PubMed Scopus (10) Google Scholar One advantage with this method is that it can be used with any preexisting adult equation to extend its applicability to children. We noted remarkable improvements in bias and accuracy of the Lund-Malmö Revised (LMR) equation when applying the equation on age-adjusted creatinine concentrations in children with CKD.9Björk J. Nyman U. Delanaye P. et al.A novel method for creatinine adjustment makes the revised Lund-Malmö GFR equation applicable in children.Scand J Clin Lab Invest. 2020; 80: 456-463Crossref PubMed Scopus (10) Google Scholar Using the same approach, the aim of the present study was to investigate if age-adjustment of serum creatinine concentrations can make the CKD-EPI equation applicable in children (2–17 years) and increase accuracy in young adults (18–39 years). The adjustment of creatinine values in children and young adults to age 40 years are illustrated in Figure 1 and explained in detail in Methods. The age-adjusted creatinine values were used in the original CKD-EPI2Levey A.S. Stevens L.A. Schmid C.H. et al.A new equation to estimate glomerular filtration rate.Ann Intern Med. 2009; 150: 604-612Crossref PubMed Scopus (13710) Google Scholar equation for GFR estimation in children (2–17 years) and young adults (18–39 years) with 40 years as assigned age in the equation (hence denoted CKD-EPI40). Basic characteristics of the included patients in the validation cohort are presented in Table 1 and the measurement procedures in Supplementary Table S1. Validation results stratified by age and measured GFR (mGFR) (<75 and ≥75 ml/min per 1.73 m2) are presented in Table 2 and by a more detailed mGFR stratification in Supplementary Tables S2 and S3. Extensive improvements in bias, and precision and accuracy were observed for CKD-EPI40 in both children and young adults at all mGFR levels. For example, the proportions of estimation errors not exceeding 30% of mGFR (P30) increased from 12% to 75% in children and from 56% to 73% in young adults at mGFR <75 ml/min per 1.73 m2. Corresponding figures at mGFR ≥75 ml/min per 1.73 m2 were increases from 33% to 88% in children and from 83% to 92% in young adults. The pediatric CKiD equation exhibited overestimations and was less accurate than CKD-EPI40 in children: 2.8 percentage points (pp) (95% confidence interval [CI] −0.2 to 5.8 pp) and 5.4 pp (95% CI 3.8 to 7.0 pp) lower P30 at mGFR <75 and ≥75 ml/min per 1.73 m2, respectively. However, Schwartz-Lyon was the most accurate equation at mGFR <75 ml/min per 1.73 m2 in children with 9.0 pp (95% CI 6.9 to 11.2 pp) and 6.2 pp (95% CI 3.7 to 8.7 pp) higher P30 accuracies than CKiD and CKD-EPI40, respectively. Schwartz-Lyon had a P30 accuracy (87%) similar to CKD-EPI40 in children with mGFR ≥75 ml/min per 1.73 m2 but was 4.6 pp (95% CI 3.5 to 5.8 pp) higher than CKiD.Table 1Patient characteristicsChildren (2–17 yr; n = 4005)Young adults (18–39 yr; n = 3309)Characteristic<75 ml/min per 1.73 m2 (n = 932)≥75 ml/min per 1.73 m2 (n = 3073)<75 ml/min per 1.73 m2 (n = 918)≥75 ml/min per 1.73 m2 (n = 2391)Female385 (41)1309 (43)400 (44)1156 (48)Age, yr12.8 (2.9–17.7)12.0 (2.5–17.8)23 (18–39)24 (18–39)Weight, kg41 (13–80)40 (13–84)63 (39–105)5 (42–105)Height, cm149 (89–181)1.48 (90–184)168 (147–188)170 (150–189)Body surface area, m21.31 (0.54–1.96)1.29 (0.56–2.03)1.72 creatinine to age GFR, ml/min per 1.73 GFR, ml/min per 1.73 m2 glomerular filtration are presented as n to in a new Table precision, and accuracy of GFR estimating equations in children to years and adults to years stratified for mGFR <75 and ≥75 ml/min per 1.73 to <75 ml/min per 1.73 m2 (n = to to to to to to to to to to to to to to to to ≥75 ml/min per 1.73 m2 (n = to to to to to to to to to to to to to to to to adults, to <75 ml/min per 1.73 m2 (n = to to to to to to to to ≥75 ml/min per 1.73 m2 (n = to to to to to to to to Chronic Kidney Disease Epidemiology Collaboration original equation CKD-EPI40, CKD-EPI with age and creatinine values adjusted to 40 years for patients CKiD, Chronic Kidney Disease in Children estimated glomerular filtration GFR, glomerular filtration measured bias and precision of eGFR are in ml/min per 1.73 m2, accuracy as percentage and and P30 accuracy as percentage of GFR estimates within and of in are confidence in a new GFR, glomerular filtration are presented as n to Chronic Kidney Disease Epidemiology Collaboration original equation CKD-EPI40, CKD-EPI with age and creatinine values adjusted to 40 years for patients CKiD, Chronic Kidney Disease in Children estimated glomerular filtration GFR, glomerular filtration measured bias and precision of eGFR are in ml/min per 1.73 m2, accuracy as percentage and and P30 accuracy as percentage of GFR estimates within and of mGFR. in are confidence more detailed of accuracy across levels of mGFR that P30 in children was at mGFR ml/min per 1.73 m2 for CKD-EPI40 but more than for Schwartz-Lyon CKD-EPI40 in young adults in P30 accuracy with the original CKD-EPI equation at all mGFR levels ml/min per 1.73 m2 The in estimation of CKD-EPI40 was in both and and in more detailed age Tables CKD-EPI40 exhibited P30 accuracy that was at all from 40 to at mGFR both below and above 75 ml/min per 1.73 m2 and In the accuracy of the original CKD-EPI equation to below age 40 at mGFR <75 ml/min per 1.73 m2 and below age at mGFR ≥75 ml/min per 1.73 m2. accuracy in the children was noted both for CKD-EPI40 and the pediatric included the equation with age and creatinine values adjusted to years in children J. Nyman U. Delanaye P. et al.A novel method for creatinine adjustment makes the revised Lund-Malmö GFR equation applicable in children.Scand J Clin Lab Invest. 2020; 80: 456-463Crossref PubMed Scopus (10) Google Scholar and are presented in Supplementary Table In CKD-EPI40, the age-adjustment of creatinine age the adjustment at age with that the same estimates as the original equation in all adults. CKD-EPI40 and exhibited bias at all levels of eGFR in children, overestimations were observed at and eGFR levels for both CKiD and Schwartz-Lyon Figure in young adults, CKD-EPI40 and both had and bias at all levels of the of the original CKD-EPI increased at However, the of CKD-EPI40 and were For example, eGFR of ml/min per 1.73 m2 for a young adult to the CKD-EPI40 accuracy interval from to ml/min per 1.73 m2, that mGFR is and ml/min per 1.73 m2 with Figure novel method based on sex-specific creatinine growth curves makes it to creatinine values childhood and young to corresponding levels of a adult Using adjustment to age 40 validation results that this makes the CKD-EPI equation applicable for the full age including young children, adolescents, and young adults of renal function. In CKD-EPI40 the pediatric CKiD equation recommended by Kidney Disease: Improving Global Disease: Improving Global Outcomes (KDIGO) CKD Work GroupKDIGO 2012 clinical practice guideline for the evaluation and management of chronic kidney disease.Kidney Int Suppl. 2013; 3: 1-150Abstract Full Text Full Text PDF Scopus (1298) Google Scholar in all age and using data on The accuracy of CKD-EPI40 was similar to the equation when in the same pediatric J. Nyman U. Delanaye P. et al.A novel method for creatinine adjustment makes the revised Lund-Malmö GFR equation applicable in children.Scand J Clin Lab Invest. 2020; 80: 456-463Crossref PubMed Scopus (10) Google Scholar CKD-EPI40 exhibited P30 accuracy at mGFR ml/min per 1.73 m2, included of the children for GFR in this pediatric The estimated P30 accuracy was at CKD for children of 75 ml/min per 1.73 P. A. et a for Am Soc Nephrol. 2019; PubMed Scopus Google Scholar height can precision and accuracy in children of all with G.J. the in estimating glomerular filtration rate in children and 2014; PubMed Scopus Google Scholar was noted to some with the Schwartz-Lyon equation in the present but that equation P30 accuracy when mGFR was ml/min per 1.73 m2. validation that GFR equations are more than creatinine-based equations in children with J. Nyman U. U. et of creatinine and GFR estimating equations in a large multicentre cohort of Nephrol. 2019; PubMed Scopus Google Scholar is if is used in the children age for both CKD-EPI40 and the pediatric equations exhibited CKD-EPI40 exhibited increased accuracy that was similar to in young adults, owing to both bias and improved The for the when the CKD-EPI equation is used age-adjusted creatinine values young adults is the GFR of per across the entire by the equation at a creatinine However, renal function to age H. L. et filtration rate in kidney a the of the full age spectrum PubMed Scopus Google Scholar but with the CKD-EPI equation of age have higher eGFR than of age 40 with the same creatinine of the original CKD-EPI equation is to age to 40 years in the equation for all patients than this is less age be as to the of creatinine We to recalculate creatinine levels to age 40 for the creatinine growth curves levels at age for both and proposed adjustment strategy for creatinine childhood and young is J. Nyman U. Delanaye P. et al.A novel method for creatinine adjustment makes the revised Lund-Malmö GFR equation applicable in children.Scand J Clin Lab Invest. 2020; 80: 456-463Crossref PubMed Scopus (10) Google the original of the GFR equation can be the same equation can be used for most patients across the entire in when a is from pediatric to adult height is not in the GFR estimation for most children, it to eGFR by the and creatinine intervals for adults be used if not for children at age of the present study was that the validation of eGFR was in patients that were from the data used when the creatinine growth curves were The of the validation cohort children and 3309 young led to in the metrics the in the estimated P30 accuracy was at most The used for validation included patients from the and Thus, not to the creatinine growth curves and the improvements in estimation accuracy for CKD-EPI40 are to However, the same be to use for and for that creatinine growth curves are that of growth in and creatinine levels childhood and study was the of patients with mGFR ml/min per 1.73 12% children and young adults. most the of CKD in age as the validation data were from for the children with mGFR ml/min per 1.73 m2 in the present study is more than the children used in the CKiD validation G.J. Munoz A. Schneider M.F. et al.New equations to estimate GFR in children with CKD.J Am Soc Nephrol. 2009; 20: 629-637Crossref PubMed Scopus (2110) Google Scholar and the young adults at this mGFR is more than the young adults in the CKD-EPI validation L.A. Schmid C.H. et of the CKD Epidemiology Collaboration (CKD-EPI) and the of in Disease study equations for estimating GFR levels above J Kidney Full Text Full Text PDF PubMed Scopus Google Scholar The creatinine growth curves were based on patients with renal function. is that the of the growth curves be the same but in patients with renal function. The observed of CKD-EPI40 when in patients with mGFR that this is In the present study how age-adjustment of creatinine in children and young adults can make the used CKD-EPI equation applicable across the full spectrum of age and renal function its on a method for in creatinine levels by et L. L. L. et al.A new equation to estimate the glomerular filtration rate in children, adolescents and young 2014; PubMed Scopus Google Scholar have creatinine growth curves from a cohort of patients years from at in (n = in (n = and in (n = J. Nyman U. Delanaye P. et al.A novel method for creatinine adjustment makes the revised Lund-Malmö GFR equation applicable in children.Scand J Clin Lab Invest. 2020; 80: 456-463Crossref PubMed Scopus (10) Google Scholar The cohort included in and age years). serum creatinine values for and at 40 years of age were and respectively. The creatinine growth curves were for and using with of age as is the actual creatinine measured in and is the The estimated of creatinine concentrations at age from the growth curves for both and were within the intervals for creatinine Table The creatinine growth curves can be used to actual creatinine values of children and young adults to adult at a to as age-adjusted creatinine In the present used age 40 years as in the CKD-EPI equation in to the of GFR noted in the transition to young H. Björk J. Bökenkamp A. et al.Estimating glomerular filtration rate at the transition from pediatric to adult care.Kidney Int. 2019; 95: 1234-1243Abstract Full Text Full Text PDF PubMed Scopus (15) Google Scholar The creatinine values for (n = and (n = 40 years in the cohort were and respectively. The of creatinine children and young adults years) to age 40 was using the from the creatinine growth For patients than 40 age = 40 was used in the adjusted CKD-EPI equation GFR was estimated as the was age 40 of actual For patients actual age and creatinine = are that CKD-EPI40 the same estimates as the original CKD-EPI equation. Thus, CKD-EPI40 the original CKD-EPI A.S. Stevens L.A. Schmid C.H. et al.A new equation to estimate glomerular filtration rate.Ann Intern Med. 2009; 150: 604-612Crossref PubMed Scopus (13710) Google Scholar and can be in the age-adjusted creatinine actual creatinine and the of actual age and 40 on renal of as a of GFR and were by the Kidney from used in cross-sectional and J. Nyman U. U. et of creatinine and GFR estimating equations in a large multicentre cohort of Nephrol. 2019; PubMed Scopus Google Scholar from the J. et more renal function than creatinine in children for PubMed Scopus (36) Google Scholar, et estimation of glomerular filtration rate in children: to the Schwartz 2013; Full Text Full Text PDF PubMed Scopus Google Scholar, A. et of estimating equations for GFR in children with a the study.Clin J Am Soc Nephrol. 2013; PubMed Scopus Google Scholar, A. M. et of a new estimating equation for glomerular filtration rate by use of to the 2014; PubMed Scopus Google Scholar, et eGFR reporting for children PubMed Scopus (10) Google H. Delanaye P. et al.Estimating glomerular filtration rate for the full age spectrum from serum creatinine and Google H. Delanaye P. et al.Estimating glomerular filtration rate for the full age spectrum from serum creatinine and Google H. L. L. et estimated glomerular filtration rate equation for the full age 2016; PubMed Scopus Google and A. M. et of a new estimating equation for glomerular filtration rate by use of to the 2014; PubMed Scopus Google Scholar J. Nyman U. U. et of creatinine and GFR estimating equations in a large multicentre cohort of Nephrol. 2019; PubMed Scopus Google Scholar and J. Nyman U. U. et of creatinine and GFR estimating equations in a large multicentre cohort of Nephrol. 2019; PubMed Scopus Google and adult J. Nyman U. Courbebaisse M. et al.Prospects for improved GFR estimation based on creatinine—results from a transnational multicentre study.Clin Kidney J. 2020; 13: 674-683Crossref PubMed Google Scholar from and A. Delanaye P. et of creatinine and glomerular filtration rate estimating equations in a 2013; PubMed Scopus Google Courbebaisse M. et of estimation measurement of glomerular filtration rate on the of kidney Int. 2019; 95: Full Text Full Text PDF PubMed Scopus Google U. Grubb A. Larsson A. et al.The revised Lund-Malmö GFR estimating equation outperforms MDRD and CKD-EPI across GFR, age and BMI intervals in a large Swedish population.Clin Chem Lab Med. 2014; 52: 815-824Crossref PubMed Scopus (97) Google A. M. et of a new estimating equation for glomerular filtration rate by use of to the 2014; PubMed Scopus Google J. Nyman U. et of the Chronic Kidney Disease Epidemiology (CKD-EPI) and of in Disease equations to estimate glomerular filtration rate in a large Swedish clinical J Nephrol. 2012; PubMed Scopus Google Scholar J. Nyman U. Courbebaisse M. et al.Prospects for improved GFR estimation based on creatinine—results from a transnational multicentre study.Clin Kidney J. 2020; 13: 674-683Crossref PubMed Google Scholar and J. Nyman U. Courbebaisse M. et al.Prospects for improved GFR estimation based on creatinine—results from a transnational multicentre study.Clin Kidney J. 2020; 13: 674-683Crossref PubMed Google and the et al.Estimating the glomerular filtration rate from serum creatinine is than from for with chronic kidney disease.Kidney Int. 2013; Full Text Full Text PDF PubMed Scopus Google Scholar and Chronic H. Delanaye P. et al.Estimating glomerular filtration rate for the full age spectrum from serum creatinine and Google H. L. L. et estimated glomerular filtration rate equation for the full age 2016; PubMed Scopus Google et al.The Chronic and Am Soc Nephrol. PubMed Google et al.Estimating GFR in the Chronic J Kidney 2012; Full Text Full Text PDF PubMed Scopus Google For this a (n = of all data from the to the measurement of GFR in children (n = and adults (n = full years of age Supplementary Table The adult patients from the cohort were included in the validation when the original CKD-EPI A.S. Stevens L.A. Schmid C.H. et al.A new equation to estimate glomerular filtration rate.Ann Intern Med. 2009; 150: 604-612Crossref PubMed Scopus (13710) Google Scholar The present pediatric cohort is to the validation cohort in original when the creatinine growth curves were and used to the J. Nyman U. Delanaye P. et al.A novel method for creatinine adjustment makes the revised Lund-Malmö GFR equation applicable in children.Scand J Clin Lab Invest. 2020; 80: 456-463Crossref PubMed Scopus (10) Google Scholar the of it is the cohort used for validation of GFR equations in children and young adults. data were in at for the present procedures and data the for in the of of and revised in For this of retrospective all data were any was not to the in the study for of mGFR included renal of and and of and Table all as Björk J. et a J Kidney 2014; Full Text Full Text PDF PubMed Scopus Google Scholar used creatinine to and of and Supplementary Table Validation results for the adjusted CKD-EPI40 equation were with the original CKD-EPI equation adjustment of age and creatinine and 2 pediatric equations with creatinine in and height in CKiD bedside”) equation3Schwartz G.J. Munoz A. Schneider M.F. et al.New equations to estimate GFR in children with CKD.J Am Soc Nephrol. 2009; 20: 629-637Crossref PubMed Scopus (2110) Google Schwartz-Lyon Souza Rabilloud M. Cochat P. et is for all 2012; PubMed Scopus Google that when Schwartz-Lyon is applied in there is for a a in eGFR of at age Schwartz-Lyon and CKiD are In validation results in children and young adults for CKD-EPI40 were further with the J. Nyman U. Delanaye P. et al.A novel method for creatinine adjustment makes the revised Lund-Malmö GFR equation applicable in children.Scand J Clin Lab Invest. 2020; 80: 456-463Crossref PubMed Scopus (10) Google Scholar The validation of eGFR mGFR on bias, precision, and L.A. Schmid C.H. the of equations for estimating glomerular filtration Nephrol. Google Scholar was as the of eGFR and precision was as the of eGFR mGFR. was from the and as the percentage and as the percentage of estimates within and of mGFR and P30 accuracy of is to be for clinical by the Kidney but the is to P30 Kidney clinical practice for chronic kidney and of laboratory for clinical of kidney of J Kidney Full Text Full Text PDF PubMed Scopus Google Scholar in P30 accuracy were with the use of for validation results were presented for children and young adults. results were further stratified for mGFR below and above 75 ml/min per 1.73 m2, a GFR below 75 ml/min per 1.73 m2 been as a for the of CKD in children and in adult than 40 P. A. et a for Am Soc Nephrol. 2019; PubMed Scopus Google Scholar detailed with to and age were We illustrated how P30 across the full of mGFR and across age with the use of with of the and was to the when to with the corresponding results stratified by mGFR was made estimation errors stratified by estimated J. Grubb A. et of GFR estimating equations stratified by measured estimated for J Kidney Full Text Full Text PDF PubMed Scopus (10) Google Scholar were with the use of with and as to how the estimation errors across eGFR for J. Grubb A. et a novel to of estimated J Clin Lab Invest. PubMed Scopus Google Scholar In the estimation errors in ml/min per 1.73 m2 using the and the accuracy interval the estimation with The was to the to of the estimated GFR values for equation to the in the of the and have for the in for estimation of GFR based on the creatinine equations presented in this with of any of the included from the The used in this study is by the and of the can be made for on from but a new and the of of the data can for the data at by the Swedish The Chronic study was by the and by the of and and Kidney The data from the study were by the was not in with of the study and not the of the the the We are to the data and for the and Bökenkamp The Courbebaisse de de and Grubb and de de and and We and de for GFR at and respectively. with Supplementary

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