title: Risk factors for acute kidney injury in older adults with critical illness: a retrospective cohort study.
abstract: BACKGROUND
  Risk for acute kidney injury (AKI) in older adults has not been evaluated systematically. We sought to delineate the determinants of risk for AKI in older compared with younger adults.
  
  
  METHODS
  Retrospective analysis of patients hospitalized in July 2000 to September 2008.
  
  
  METHODS
  We identified all adult patients admitted to an intensive care unit (n=45,655) in a large tertiary-care university hospital system. We excluded patients receiving dialysis or a kidney transplant prior to hospital admission and patients with baseline creatinine levels ≥ 4mg/dL, liver transplantation, indeterminate AKI status, or unknown age, leaving 39,938 patients.
  
  
  METHODS
  We collected data for multiple susceptibilities and exposures, including age, sex, race, body mass, comorbid conditions, severity of illness, baseline kidney function, sepsis, and shock.
  
  
  RESULTS
  We defined AKI according to KDIGO (Kidney Disease: Improving Global Outcomes) criteria. We examined susceptibilities and exposures across age strata for impact on the development of AKI.
  
  
  METHODS
  We calculated area under the receiver operating characteristic curve (AUC) for prediction of AKI across age groups.
  
  
  RESULTS
  25,230 (63.2%) patients were 55 years or older. Overall, 25,120 (62.9%) patients developed AKI (69.2% aged ≥55 years). Examples of risk factors for AKI in the oldest age category (≥75 years) were drugs (vancomycin, aminoglycosides, and nonsteroidal anti-inflammatories), history of hypertension (OR, 1.13; 95% CI, 1.02-1.25), and sepsis (OR, 2.12; 95% CI, 1.68-2.67). Fewer variables remained predictive of AKI as age increased and the model for older patients was less predictive (P<0.001). For the age categories 18 to 54, 55 to 64, 65 to 74, and 75 years or older, AUCs were 0.744 (95% CI, 0.735-0.752), 0.714 (95% CI, 0.702-0.726), 0.706 (95% CI, 0.693-0.718), and 0.673 (95% CI, 0.661-0.685), respectively.
  
  
  CONCLUSIONS
  Analysis may not apply to non-intensive care unit patients.
  
  
  CONCLUSIONS
  The likelihood of developing AKI increases with age; however, the same variables are less predictive for AKI as age increases. Efforts to quantify risk for AKI may be more difficult in older adults.
authors.affiliation: The Center for Critical Care Nephology, Department of Critical Care Medicine, University of Pittsburgh School of Medicine, and University of Pittsburgh Medical Center, Pittsburgh, PA; Department of Pharmacy and Therapeutics, University of Pittsburgh School of Pharmacy, Pittsburgh, PA.
authors.forename: Sandra L
authors.initials: SL
authors.lastname: Kane-Gill
authors.affiliation: The Center for Critical Care Nephology, Department of Critical Care Medicine, University of Pittsburgh School of Medicine, and University of Pittsburgh Medical Center, Pittsburgh, PA; CRISMA (Clinical Research, Investigation, and Systems Modeling of Acute Illness) Center, Department of Critical Care Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA; Department of Biostatistics, University of Pittsburgh Graduate School of Public Health, Pittsburgh, PA.
authors.forename: Florentina E
authors.initials: FE
authors.lastname: Sileanu
authors.affiliation: The Center for Critical Care Nephology, Department of Critical Care Medicine, University of Pittsburgh School of Medicine, and University of Pittsburgh Medical Center, Pittsburgh, PA; CRISMA (Clinical Research, Investigation, and Systems Modeling of Acute Illness) Center, Department of Critical Care Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA.
authors.forename: Raghavan
authors.initials: R
authors.lastname: Murugan
authors.affiliation: Department of Pharmacy and Therapeutics, University of Pittsburgh School of Pharmacy, Pittsburgh, PA.
authors.forename: Gregory S
authors.initials: GS
authors.lastname: Trietley
authors.affiliation: Department of Biomedical Informatics, University of Pittsburgh School of Medicine, Pittsburgh, PA; Division of Geriatric Medicine, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA.
authors.forename: Steven M
authors.initials: SM
authors.lastname: Handler
authors.affiliation: The Center for Critical Care Nephology, Department of Critical Care Medicine, University of Pittsburgh School of Medicine, and University of Pittsburgh Medical Center, Pittsburgh, PA; CRISMA (Clinical Research, Investigation, and Systems Modeling of Acute Illness) Center, Department of Critical Care Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA. Electronic address: kellumja@ccm.upmc.edu.
authors.forename: John A
authors.initials: JA
authors.lastname: Kellum
mesh_terms: D058186:Acute Kidney Injury / Q000453:epidemiology*; D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000617:Aminoglycosides / Q000627:therapeutic use; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000627:therapeutic use*; D019540:Area Under Curve; D015331:Cohort Studies; D015897:Comorbidity; D016638:Critical Illness / Q000453:epidemiology*; D005260:Female; D006801:Humans; D006973:Hypertension / Q000453:epidemiology*; D007362:Intensive Care Units; D008297:Male; D008875:Middle Aged; D012372:ROC Curve; D012189:Retrospective Studies; D012307:Risk Factors; D018805:Sepsis / Q000453:epidemiology*; D014640:Vancomycin / Q000627:therapeutic use; D055815:Young Adult
chemical_list: D000617:Aminoglycosides; D000900:Anti-Bacterial Agents; D000894:Anti-Inflammatory Agents, Non-Steroidal; D014640:Vancomycin
keywords: Acute kidney injury (AKI); age; chronic kidney disease (CKD); critical illness; elderly; intensive care unit (ICU); older; risk; risk prediction; susceptibilities and exposures