title: The Association Between Urine Output, Creatinine Elevation, and Death.
abstract: BACKGROUND
  Acute kidney injury can be defined by a fall in urine output, and urine output criteria may be more sensitive in identifying acute kidney injury than traditional serum creatinine criteria. However, as pointed out in the Kidney Disease Improving Global Outcome guidelines, the association of urine output with subsequent creatinine elevations and death is poorly characterized. The purpose of this study was to determine what degrees of reduced urine output are associated with subsequent creatinine elevation and death.
  
  
  METHODS
  This was a retrospective cohort study of adult patients (age ≥18 years) cared for in a cardiovascular intensive care unit after undergoing cardiac operations in a tertiary care university medical center. All adult patients who underwent cardiac operations and were not receiving dialysis preoperatively were studied. The development of acute kidney injury was defined as an increase in creatinine of more than 0.3 mg/dL or by more than 50% above baseline by postoperative day 3.
  
  
  RESULTS
  Acute kidney injury developed in 1,061 of 4,195 patients (25%). Urine output had moderate discrimination in predicting subsequent acute kidney injury (C statistic = .637 ± .054). Lower urine output and longer duration of low urine output were associated with greater odds of developing acute kidney injury and death.
  
  
  CONCLUSIONS
  We found that there is similar accuracy in using urine output corrected for actual, ideal, or adjusted weight to discriminate future acute kidney injury by creatinine elevation and recommend using actual weight for its simplicity. We also found that low urine output is associated with subsequent acute kidney injury and that the association is greater for lower urine output and for low urine output of longer durations. Low urine output (<0.2 mL · kg-1· h-1), even in the absence of acute kidney injury by creatinine elevation, is independently associated with mortality.
authors.affiliation: Department of Anesthesiology, University of Michigan, Ann Arbor, Michigan. Electronic address: engorenm@med.umich.edu.
authors.forename: Milo
authors.initials: M
authors.lastname: Engoren
authors.affiliation: Department of Anesthesiology, University of Michigan, Ann Arbor, Michigan.
authors.forename: Michael D
authors.initials: MD
authors.lastname: Maile
authors.affiliation: Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan.
authors.forename: Michael
authors.initials: M
authors.lastname: Heung
authors.affiliation: Department of Anesthesiology, University of Michigan, Ann Arbor, Michigan.
authors.forename: Elizabeth S
authors.initials: ES
authors.lastname: Jewell
authors.affiliation: Department of Anesthesiology, University of Michigan, Ann Arbor, Michigan; Department of Anesthesiology, Beaumont Health Center, Royal Oak, Michigan.
authors.forename: Christie
authors.initials: C
authors.lastname: Vahabzadeh
authors.affiliation: Department of Cardiothoracic Surgery, University of Michigan, Ann Arbor, Michigan.
authors.forename: Jonathan W
authors.initials: JW
authors.lastname: Haft
authors.affiliation: Department of Anesthesiology, University of Michigan, Ann Arbor, Michigan.
authors.forename: Sachin
authors.initials: S
authors.lastname: Kheterpal
mesh_terms: D058186:Acute Kidney Injury / Q000175:diagnosis* / Q000378:metabolism* / Q000401:mortality; D000328:Adult; D000368:Aged; D006348:Cardiac Surgical Procedures / Q000009:adverse effects; D003404:Creatinine / Q000378:metabolism*; D005260:Female; D006801:Humans; D007677:Kidney Function Tests; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000175:diagnosis* / Q000378:metabolism* / Q000401:mortality; D012189:Retrospective Studies; D012307:Risk Factors; D015996:Survival Rate; D014554:Urination / Q000502:physiology*
chemical_list: D003404:Creatinine