title: Estimating glomerular filtration rate for the full age spectrum from serum creatinine and cystatin C.
abstract: We recently published and validated the new serum creatinine (Scr)-based full-age-spectrum equation (FAS crea ) for estimating the glomerular filtration rate (GFR) for healthy and kidney-diseased subjects of all ages. The equation was based on the concept of normalized Scr and shows equivalent to superior prediction performance to the currently recommended equations for children, adolescents, adults and older adults.
  
  
  
  Based on an evaluation of the serum cystatin C (ScysC) distribution, we defined normalization constants for ScysC ( Q cysC  =   0.82 mg/L for ages <70 years and Q cysC  =   0.95 mg/L for ages ≥70 years). By replacing Scr/ Q crea in the FAS crea equation with ScysC/ Q cysC , or with the average of both normalized biomarkers, we obtained new ScysC-based (FAS cysC ) and combined Scr-/ScysC-based FAS equations (FAS combi ). To validate the new FAS cysC and FAS combi we collected data on measured GFR, Scr, ScysC, age, gender, height and weight from 11 different cohorts including n  = 6132 unique white subjects (368 children, aged ≤18 years, 4295 adults and 1469 older adults, aged ≥70 years).
  
  
  
  In children and adolescents, the new FAS cysC equation showed significantly better performance [percentage of patients within 30% of mGFR (P30) = 86.1%] than the Caucasian Asian Paediatric Adult Cohort equation (P30 = 76.6%; P < 0.0001), or the ScysC-based Schwartz equation (P30 = 68.8%; P < 0.0001) and the FAS combi equation outperformed all equations with P30 = 92.1% (P < 0.0001). In adults, the FAS cysC equation (P30 = 82.6%) performed equally as well as the Chronic Kidney Disease Epidemiology Collaboration equation (CKD-EPI cysC ) (P30 = 80.4%) and the FAS combi equation (P30 = 89.9%) was also equal to the combined CKD-EPI equation (P30 = 88.2%). In older adults, FAS cysC was superior (P30 = 88.2%) to CKD-EPI cysC (P30 = 84.4%; P < 0.0001) and the FAS combi equation (P30 = 91.2%) showed significantly higher performance than the combined CKD-EPI equation (P30 = 85.6%) (P < 0.0001).
  
  
  
  The FAS equation is not only applicable to all ages, but also for all recommended renal biomarkers and their combinations.
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: Nephrology-Dialysis-Transplantation, University of Liège, CHU Sart Tilman, Liège, Belgium.
authors.forename: Pierre
authors.initials: P
authors.lastname: Delanaye
authors.affiliation: Charité University Hospital, Institute of Public Health, Berlin, Germany.
authors.forename: Elke
authors.initials: E
authors.lastname: Schaeffner
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: 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, 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 de Caxias do Sul - Programa de Pós Graduação em Ciências da Saúde, Brazil.
authors.forename: Vandréa
authors.initials: V
authors.lastname: De Souza
authors.affiliation: Universidade de Caxias do Sul - Programa de Pós Graduação em Ciências da Saúde, Brazil.|Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, Brazil.
authors.forename: Luciano
authors.initials: L
authors.lastname: Selistre
authors.affiliation: Department of Nuclear Medicine & Molecular Imaging, University Hospital Leuven, Leuven, Belgium.
authors.forename: Karolien
authors.initials: K
authors.lastname: Goffin
authors.affiliation: Department of Cardiovascular Sciences, University Hospital Leuven, Leuven, Belgium.|Department of Laboratory Medicine, University Hospital Leuven, Leuven, Belgium.
authors.forename: Steven
authors.initials: S
authors.lastname: Pauwels
authors.affiliation: Service de Néphrologie, Dialyse et Transplantation Rénale, Hôpital Nord, CHU de Saint-Etienne, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Mariat
authors.affiliation: Department of Renal Physiology, Hôpital Bichat, AP-HP and Paris Diderot University, Paris, France.
authors.forename: Martin
authors.initials: M
authors.lastname: Flamant
authors.affiliation: Charité University Hospital, Institute of Public Health, Berlin, Germany.
authors.forename: Natalie
authors.initials: N
authors.lastname: Ebert
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000097:blood; D002648:Child; D002675:Child, Preschool; D003404:Creatinine / Q000097:blood*; D055316:Cystatin C / Q000097:blood*; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D007223:Infant; D007677:Kidney Function Tests; D008297:Male; D008875:Middle Aged; D051436:Renal Insufficiency, Chronic / Q000097:blood* / Q000175:diagnosis; D044465:White People; D055815:Young Adult
chemical_list: D015415:Biomarkers; D055316:Cystatin C; D003404:Creatinine
keywords: all ages; all renal biomarkers; combined FAS equation; cystatin C; serum creatinine