title: Agreement between Chronic Kidney Disease Epidemiological Collaboration and Berlin Initiative Study equations for estimating glomerular filtration rate in older people: The Invecchiare in Chianti (Aging in Chianti Region) study.
abstract: OBJECTIVE
  The aim was to investigate to what extent chronic kidney disease (CKD) can be staged interchangeably by Chronic Kidney Disease Epidemiological Collaboration (CKD-EPI) and by Berlin Initiative Study (BIS) equations, and to verify whether cystatin C can improve concordance between formulas.
  
  
  METHODS
  Our series consisted of 828 community-dwelling individuals aged 65 years or older enrolled in the Invecchiare in Chianti Study ("Aging in the Chianti Region"). Estimated glomerular filtration rate was calculated using the creatinine-based CKD-EPI, creatinine/cystatin C-based CKD-EPI, creatinine-based BIS and creatinine/cystatin C-based BIS equations. Agreement and sources of discrepancy between equations in identifying people with different degrees of kidney dysfunction was investigated by κ statistic and Bland-Altman plots.
  
  
  RESULTS
  Overall, CKD-EPI values were higher than that obtained with BIS equations, especially for eGFR = 30-60 mL/min/1.73 m2. A total of 191 out of 828 participants were classified in stage 2 by the creatinine-based CKD-EPI and in stage 3a by the creatinine-based BIS equation, whereas 123 participants were classified in stage 2 by creatinine/cystatin C-based CKD-EPI and in stage 3a by the creatinine/cystatin C-based BIS equation. A total of 27 participants were classified in stage 3a by creatinine-based CKD-EPI and in stage 3b by creatinine-based BIS equation, whereas 18 were classified as stage 3a by creatinine/cystatin C-based CKD-EPI and stage 3b by the creatinine/cystatin C-based BIS equation.
  
  
  CONCLUSIONS
  Despite a fair overall concordance, the CKD-EPI and BIS equations cannot be considered interchangeable to assess estimated glomerular filtration rate in older people, and using creatinine/cystatin C-based rather than creatinine-based equations only marginally improves the concordance between CKD-EPI and BIS. Disagreement between equations might significantly impact the applications of stage-specific measures for managing CKD among older people. Geriatr Gerontol Int 2017; 17: 1559-1567.
authors.affiliation: Unit of Geriatric Pharmacoepidemiology, Italian National Research Center on Aging (INRCA), Cosenza, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Corsonello
authors.affiliation: Unit of Geriatric Medicine, University "Campus Biomedico", Rome, Italy.
authors.forename: Claudio
authors.initials: C
authors.lastname: Pedone
authors.affiliation: Healthcare Agency of Florence, Florence, Italy.
authors.forename: Stefania
authors.initials: S
authors.lastname: Bandinelli
authors.affiliation: National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA.
authors.forename: Luigi
authors.initials: L
authors.lastname: Ferrucci
authors.affiliation: Unit of Geriatric Medicine, University "Campus Biomedico", Rome, Italy.|"Cittadella della Carità" Foundation, Taranto, Italy.
authors.forename: Raffaele
authors.initials: R
authors.lastname: Antonelli Incalzi
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D003404:Creatinine / Q000378:metabolism; D055316:Cystatin C / Q000378:metabolism; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D008297:Male; D051436:Renal Insufficiency, Chronic / Q000175:diagnosis*; D015203:Reproducibility of Results
chemical_list: D055316:Cystatin C; D003404:Creatinine
keywords: Berlin Initiative Study; Chronic Kidney Disease Epidemiological Collaboration; chronic kidney disease; estimated glomerular filtration rate; misclassification