title: Early reversible acute kidney injury is associated with improved survival in septic shock.
abstract: BACKGROUND
  The fact that acute kidney injury (AKI) is associated with worse clinical outcomes forms the basis of most AKI prognostic scoring systems. However, early reversibility of renal dysfunction in acute illness is not considered in such systems. We sought to determine whether early (≤24 hours after shock documentation) reversibility of AKI was independently associated with in-hospital mortality in septic shock.
  
  
  METHODS
  Patient information was derived from an international database of septic shock cases from 28 different institutions in Canada, the United States and Saudi Arabia. Data from a final cohort of 5443 patients admitted with septic shock between Jan 1996 and Dec 2009 was analyzed. The following 4 definitions were used in regards to AKI status: (1) reversible AKI = AKI of any RIFLE severity prevalent at shock diagnosis or incident at 6 hours post-diagnosis that reverses by 24 hours, (2) persistent AKI = AKI prevalent at shock diagnosis and persisting during the entire 24 hours post-shock diagnosis, (3) new AKI = AKI incident between 6 and 24 hours post-shock diagnosis, and (4) improved AKI = AKI prevalent at shock diagnosis or incident at 6 hours post followed by improvement of AKI severity across at least one RIFLE category over the first 24 hours. Cox proportional hazards were used to determine the association between AKI status and in-hospital mortality.
  
  
  RESULTS
  During the first 24 hours, reversible AKI occurred in 13.0%, persistent AKI in 54.9%, new AKI in 11.7%, and no AKI in 22.4%. In adjusted analyses, reversible AKI was associated with improved survival (HR, 0.64; 95% CI, 0.53-0.77) compared to no AKI (referent), persistent AKI (HR, 0.99; 95% CI, 0.88-1.11), and new AKI (HR, 1.41; 95% CI, 1.22-1.62). Improved AKI occurred in 19.1% with improvement across any RIFLE category associated with a significant decrease in mortality (HR, 0.53; 95% CI, 0.45-0.63). More rapid antimicrobial administration, lower Acute Physiology and Chronic Health Evaluation II score, lower age, and a smaller number of failed organs (excluding renal) on the day of shock as well as community-acquired infection were independently associated with reversible AKI.
  
  
  CONCLUSIONS
  In septic shock, reversible AKI within the first 24 hours of admission confers a survival benefit compared to no, new, or persistent AKI. Prognostic AKI classification schemes should consider integration of early AKI reversibility into the scoring system.
authors.affiliation: Ottawa Hospital Research Institute, University of Ottawa, Ottawa, Canada.
authors.forename: Manish M
authors.initials: MM
authors.lastname: Sood
authors.affiliation: Section of Nephrology, University of Manitoba, Manitoba, Canada.
authors.forename: Leigh Anne
authors.initials: LA
authors.lastname: Shafer
authors.affiliation: Section of Nephrology, University of Manitoba, Manitoba, Canada.
authors.forename: Julie
authors.initials: J
authors.lastname: Ho
authors.affiliation: Section of Nephrology, University of Manitoba, Manitoba, Canada.
authors.forename: Martina
authors.initials: M
authors.lastname: Reslerova
authors.affiliation: Richmond General Hospital, Vancouver, British Columbia, Canada.
authors.forename: Greg
authors.initials: G
authors.lastname: Martinka
authors.affiliation: Royal Columbian Hospital, Vancouver, British Columbia, Canada.
authors.forename: Sean
authors.initials: S
authors.lastname: Keenan
authors.affiliation: McGill University, Montreal Quebec, Canada.
authors.forename: Sandra
authors.initials: S
authors.lastname: Dial
authors.affiliation: Royal Jubilee Hospital/Victoria General Hospital, Victoria British Columbia, Canada.
authors.forename: Gordon
authors.initials: G
authors.lastname: Wood
authors.affiliation: Section of Nephrology, University of Manitoba, Manitoba, Canada.
authors.forename: Claudio
authors.initials: C
authors.lastname: Rigatto
authors.affiliation: Section of Critical Care Medicine, University of Manitoba, Manitoba, Canada.
authors.forename: Anand
authors.initials: A
authors.lastname: Kumar
mesh_terms: D018806:APACHE; D058186:Acute Kidney Injury / Q000145:classification / Q000188:drug therapy* / Q000401:mortality*; D000328:Adult; D000368:Aged; D000900:Anti-Bacterial Agents / Q000008:administration & dosage*; D002170:Canada; D005260:Female; D017052:Hospital Mortality; D006801:Humans; D007676:Kidney Failure, Chronic / Q000401:mortality; D007902:Length of Stay; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011379:Prognosis; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D012529:Saudi Arabia; D018805:Sepsis / Q000401:mortality; D012772:Shock, Septic / Q000175:diagnosis / Q000188:drug therapy* / Q000401:mortality*; D013997:Time Factors; D014481:United States
chemical_list: D000900:Anti-Bacterial Agents
keywords: Acute renal failure; Acute tubular necrosis; Outcome; Severe sepsis