title: Glomerular filtration rate, proteinuria, and the incidence and consequences of acute kidney injury: a cohort study.
abstract: BACKGROUND
  Low values of estimated glomerular filtration rate (eGFR) predispose to acute kidney injury, and proteinuria is a marker of kidney disease. We aimed to investigate how eGFR and proteinuria jointly modified the risks of acute kidney injury and subsequent adverse clinical outcomes.
  
  
  METHODS
  We did a cohort study of 920,985 adults residing in Alberta, Canada, between 2002 and 2007. Participants not needing chronic dialysis at baseline and with at least one outpatient measurement of both serum creatinine concentration and proteinuria (urine dipstick or albumin-creatinine ratio) were included. We assessed hospital admission with acute kidney injury with validated administrative codes; other outcomes were all-cause mortality and a composite renal outcome of end-stage renal disease or doubling of serum creatinine concentration.
  
  
  RESULTS
  During median follow-up of 35 months (range 0-59 months), 6520 (0·7%) participants were admitted with acute kidney injury. In those with eGFR 60 mL/min per 1·73 m(2) or greater, the adjusted risk of admission with this disorder was about 4 times higher in those with heavy proteinuria measured by dipstick (rate ratio 4·4 vs no proteinuria, 95% CI 3·7-5·2). The adjusted rates of admission with acute kidney injury and kidney injury needing dialysis remained high in participants with heavy dipstick proteinuria for all values of eGFR. The adjusted rates of death and the composite renal outcome were also high in participants admitted with acute kidney injury, although the rise associated with this injury was attenuated in those with low baseline eGFR and heavy proteinuria.
  
  
  CONCLUSIONS
  These findings suggest that information on proteinuria and eGFR should be used together when identifying people at risk of acute kidney injury, and that an episode of acute kidney injury provides further long-term prognostic information in addition to eGFR and proteinuria.
  
  
  BACKGROUND
  The study was funded by an interdisciplinary team grant from Alberta Heritage Foundation for Medical Research.
authors.affiliation: Department of Medicine, University of Calgary, Calgary, AB, Canada.
authors.forename: Matthew T
authors.initials: MT
authors.lastname: James
authors.forename: Brenda R
authors.initials: BR
authors.lastname: Hemmelgarn
authors.forename: Natasha
authors.initials: N
authors.lastname: Wiebe
authors.forename: Neesh
authors.initials: N
authors.lastname: Pannu
authors.forename: Braden J
authors.initials: BJ
authors.lastname: Manns
authors.forename: Scott W
authors.initials: SW
authors.lastname: Klarenbach
authors.forename: Marcello
authors.initials: M
authors.lastname: Tonelli
mesh_terms: D058186:Acute Kidney Injury / Q000150:complications / Q000453:epidemiology* / Q000209:etiology* / Q000401:mortality / Q000503:physiopathology; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000416:Alberta / Q000453:epidemiology; D000419:Albuminuria / Q000150:complications; D015331:Cohort Studies; D015897:Comorbidity; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D005919:Glomerular Filtration Rate; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D015994:Incidence; D007676:Kidney Failure, Chronic / Q000453:epidemiology / Q000209:etiology; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D016012:Poisson Distribution; D011507:Proteinuria / Q000150:complications* / Q000453:epidemiology; D018570:Risk Assessment; D012307:Risk Factors