title: An estimated glomerular filtration rate equation for the full age spectrum.
abstract: Glomerular filtration rate (GFR) is accepted as the best indicator of kidney function and is commonly estimated from serum creatinine (SCr)-based equations. Separate equations have been developed for children (Schwartz equation), younger and middle-age adults [Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation] and older adults [Berlin Initiative Study 1 (BIS1) equation], and these equations lack continuity with ageing. We developed and validated an equation for estimating the glomerular filtration rate that can be used across the full age spectrum (FAS).
  
  
  
  The new FAS equation is based on normalized serum creatinine (SCr/Q), where Q is the median SCr from healthy populations to account for age and sex. Coefficients for the equation are mathematically obtained by requiring continuity during the paediatric-adult and adult-elderly transition. Research studies containing a total of 6870 healthy and kidney-diseased white individuals, including 735 children, <18 years of age, 4371 adults, between 18 and 70 years of age, and 1764 older adults, ≥70 years of age with measured GFR (inulin, iohexol and iothalamate clearance) and isotope dilution mass spectrometry-equivalent SCr, were used for the validation. Bias, precision and accuracy (P30) were evaluated.
  
  
  
  The FAS equation was less biased [-1.7 (95% CI -3.4, -0.2) versus 6.0 (4.5, 7.5)] and more accurate [87.5% (85.1, 89.9) versus 83.8% (81.1, 86.5)] than the Schwartz equation for children and adolescents; less biased [5.0 (4.5, 5.5) versus 6.3 (5.9, 6.8)] and as accurate [81.6% (80.4, 82.7) versus 81.9% (80.7, 83.0)] as the CKD-EPI equation for young and middle-age adults; and less biased [-1.1 (-1.6, -0.6) versus 5.6 (5.1, 6.2)] and more accurate [86.1% (84.4, 87.7) versus 81.8% (79.7, 84.0)] than CKD-EPI for older adults.
  
  
  
  The FAS equation has improved validity and continuity across the full age-spectrum and overcomes the problem of implausible eGFR changes in patients which would otherwise occur when switching between more age-specific equations.
authors.affiliation: Department of Public Health and Primary Care, KU Leuven Campus Kulak Kortrijk, Kortrijk, Belgium.
authors.forename: Hans
authors.initials: H
authors.lastname: Pottel
authors.affiliation: Department of Public Health and Primary Care, KU Leuven Campus Kulak Kortrijk, Kortrijk, Belgium.
authors.forename: Liesbeth
authors.initials: L
authors.lastname: Hoste
authors.affiliation: Exploration Fonctionnelle Rénale, Groupement Hospitalier Edouard Herriot, Hospices Civils de Lyon, Lyon, France.
authors.forename: Laurence
authors.initials: L
authors.lastname: Dubourg
authors.affiliation: Charité University Hospital, Institute of Public Health, Berlin, Germany.
authors.forename: Natalie
authors.initials: N
authors.lastname: Ebert
authors.affiliation: Charité University Hospital, Institute of Public Health, Berlin, Germany.
authors.forename: Elke
authors.initials: E
authors.lastname: Schaeffner
authors.affiliation: Metabolic and Renal Research Group, UiT The Arctic University of Norway, Tromsø, Norway.
authors.forename: Bjørn Odvar
authors.initials: BO
authors.lastname: Eriksen
authors.affiliation: Metabolic and Renal Research Group, UiT The Arctic University of Norway, Tromsø, Norway.
authors.forename: Toralf
authors.initials: T
authors.lastname: Melsom
authors.affiliation: Clinical Biochemistry, East Kent Hospitals University NHS Foundation Trust, Canterbury, Kent, UK.
authors.forename: Edmund J
authors.initials: EJ
authors.lastname: Lamb
authors.affiliation: Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN, USA.
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Rule
authors.affiliation: Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN, USA.
authors.forename: Stephen T
authors.initials: ST
authors.lastname: Turner
authors.affiliation: Emeritus Professor of Medicine, Geffen School of Medicine at UCLA, Laguna Niguel, CA, USA.
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Glassock
authors.affiliation: Universidade Federal do Rio Grande do Sul, FAMED - Programa de Pós Graduação em Saúde da Criança e do Adolescente, Porto Alegre, Brazil.
authors.forename: Vandréa
authors.initials: V
authors.lastname: De Souza
authors.affiliation: Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, Brazil.
authors.forename: Luciano
authors.initials: L
authors.lastname: Selistre
authors.affiliation: Service de Néphrologie, Dialyse et Transplantation Rénale, Hôpital Nord, CHU de Saint-Etienne, Saint-Etienne, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Mariat
authors.affiliation: Department of Clinical Chemistry, AZ Groeninge Hospital, Kortrijk, Belgium.
authors.forename: Frank
authors.initials: F
authors.lastname: Martens
authors.affiliation: Nephrology-Dialysis-Transplantation, University of Liège, CHU Sart Tilman, Liège, Belgium.
authors.forename: Pierre
authors.initials: P
authors.lastname: Delanaye
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D015415:Biomarkers / Q000032:analysis*; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D007223:Infant; D007668:Kidney / Q000503:physiopathology*; D007677:Kidney Function Tests; D008297:Male; D008875:Middle Aged; D008962:Models, Theoretical; D051436:Renal Insufficiency, Chronic / Q000175:diagnosis* / Q000378:metabolism; D055815:Young Adult
chemical_list: D015415:Biomarkers
keywords: FAS eGFR equation; development and validation; healthy and kidney-diseased subjects