title: The glomerular filtration rate estimated by new and old equations as a predictor of important outcomes in elderly patients.
abstract: BACKGROUND
  The prevalence of chronic kidney disease (CKD) increases with age, and new glomerular filtration rate-estimating equations have recently been validated. The epidemiology of CKD in older individuals and the relationship between a low estimated glomerular filtration rate as calculated by these equations and adverse outcomes remains unknown.
  
  
  METHODS
  Data from the BELFRAIL study, a prospective, population-based cohort study of 539 individuals aged 80 years and older, were used. For every participant, five equations were used to calculate estimated glomerular filtration rate based on serum creatinine and/or cystatin C values: MDRD, CKD-EPIcreat, CKD-EPIcyst, CKD-EPIcreatcyst, and BIS equations. The outcomes analyzed included mortality combined with the necessity of new renal replacement therapy, severe cardiovascular events, and hospitalization.
  
  
  RESULTS
  During the follow-up period, which was an average of 2.9 years, 124 participants died, 7 required renal replacement therapy, 271 were hospitalized, and 73 had a severe cardiovascular event. The prevalence of estimated glomerular filtration rate values <60 mL/min/1.73 m2 differed depending on the equation used as follows: 44% (MDRD), 45% (CKD-EPIcreat), 75% (CKD-EPIcyst), 65% (CKD-EPIcreatcyst), and 80% (BIS). All of the glomerular filtration rate-estimating equations revealed that higher cardiovascular mortality was associated with lower estimated glomerular filtration rates and that higher probabilities of hospitalization were associated with estimated glomerular filtration rates <30 mL/min/1.73 m2. A lower estimated glomerular filtration rate did not predict a higher probability of severe cardiovascular events, except when using the CKD-EPIcyst equation. By calculating the net reclassification improvement, CKD-EPIcyst and CKD-EPIcreatcyst were shown to predict mortality (+25% and +18%) and severe cardiovascular events (+7% and +9%) with the highest accuracy. The BIS equation was less accurate in predicting mortality (-12%).
  
  
  CONCLUSIONS
  Higher prevalence of CKD were found using the CKD-EPIcyst, CKD-EPIcreatcyst, and BIS equations compared with the MDRD and CKD-EPIcreat equations. The new CKD-EPIcreatcyst and CKD-EPIcyst equations appear to be better predictors of mortality and severe cardiovascular events.
authors: Department of Public Health and Primary Care, Katholieke Universiteit Leuven, Kapucijnenvoer 33, blok J, PB 7001 3000, Leuven, Belgium. gijs.vanpottelbergh@med.kuleuven.be.
authors: Gijs
authors: G
authors: Van Pottelbergh
authors: Bert
authors: B
authors: Vaes
authors: Wim
authors: W
authors: Adriaensen
authors: Cathy
authors: C
authors: Matheï
authors: Delphine
authors: D
authors: Legrand
authors: Pierre
authors: P
authors: Wallemacq
authors: Jean Marie
authors: JM
authors: Degryse
mesh_terms: D000369:Aged, 80 and over; D001530:Belgium / Q000453:epidemiology; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D005919:Glomerular Filtration Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D011159:Population Surveillance / Q000379:methods; D011237:Predictive Value of Tests; D011446:Prospective Studies; D051436:Renal Insufficiency, Chronic / Q000175:diagnosis* / Q000453:epidemiology* / Q000503:physiopathology; D016896:Treatment Outcome