title: CKD classification based on estimated GFR over three years and subsequent cardiac and mortality outcomes: a cohort study.
abstract: BACKGROUND
  It is unknown whether defining chronic kidney disease (CKD) based on one versus two estimated glomerular filtration rate (eGFR) assessments changes the prognostic importance of reduced eGFR in a community-based population.
  
  
  METHODS
  Participants in the Atherosclerosis Risk in Communities Study and the Cardiovascular Health Study were classified into 4 groups based on two eGFR assessments separated by 35.3 +/- 2.5 months: sustained eGFR < 60 mL/min per 1.73 m(2) (1 mL/sec per 1.73 m(2)); eGFR increase (change from below to above 60); eGFR decline (change from above to below 60); and eGFR persistently >or=60. Outcomes assessed in stratified multivariable Cox models included cardiac events and a composite of cardiac events, stroke, and mortality.
  
  
  RESULTS
  There were 891 (4.9%) participants with sustained eGFR < 60, 278 (1.5%) with eGFR increase, 972 (5.4%) with eGFR decline, and 15,925 (88.2%) with sustained eGFR > 60. Participants with eGFR sustained < 60 were at highest risk of cardiac and composite events [HR = 1.38 (1.15, 1.65) and 1.58 (1.41, 1.77)], respectively, followed by eGFR decline [HR = 1.20 (1.00, 1.45) and 1.32 (1.17, 1.49)]. Individuals with eGFR increase trended toward increased cardiac risk [HR = 1.25 (0.88, 1.77)] and did not significantly differ from eGFR decline for any outcome. Results were similar when estimating GFR with the CKD-EPI equation.
  
  
  CONCLUSIONS
  Individuals with persistently reduced eGFR are at highest risk of cardiovascular outcomes and mortality, while individuals with an eGFR < 60 mL/min per 1.73 m(2) at any time are at intermediate risk. Use of even a single measurement of eGFR to classify CKD in a community population appears to have prognostic value.
authors.affiliation: Division of Nephrology, Tufts Medical Center, 800 Washington Street, Boston, MA 02111, USA. dweiner@tuftsmedicalcenter.org
authors.forename: Daniel E
authors.initials: DE
authors.lastname: Weiner
authors.forename: Maria
authors.initials: M
authors.lastname: Krassilnikova
authors.forename: Hocine
authors.initials: H
authors.lastname: Tighiouart
authors.forename: Deeb N
authors.initials: DN
authors.lastname: Salem
authors.forename: Andrew S
authors.initials: AS
authors.lastname: Levey
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Sarnak
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D050197:Atherosclerosis / Q000401:mortality*; D001900:Boston / Q000453:epidemiology; D015897:Comorbidity; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D015994:Incidence; D007676:Kidney Failure, Chronic / Q000175:diagnosis* / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D018570:Risk Assessment / Q000379:methods*; D012307:Risk Factors; D012680:Sensitivity and Specificity; D020521:Stroke / Q000401:mortality*; D016019:Survival Analysis; D015996:Survival Rate