title: Impact of body mass on outcomes of geriatric postoperative acute kidney injury patients.
abstract: BACKGROUND
  Acute kidney injury (AKI) frequently occurs in hospitalized patients, particularly in the elderly. However, studies on outcome-modifying factors in geriatric patients with AKI are absent, especially the influence of body mass index (BMI).
  
  
  METHODS
  We performed a retrospective analysis of a prospectively collected multicenter observational cohort, which enrolled elderly (≥65 years) who developed AKI after major surgery in the intensive care units. We analyzed in-hospital mortality within BMI category utilizing Cox proportional hazard regression analysis and generalized additive modeling.
  
  
  RESULTS
  Data of a total of 2,015 postoperative elderly patients were retrieved and analyzed. Generalized additive modeling showed that elderly AKI patients with a BMI between 21 and 31 kg/m(2) ("normal") had a lower mortality risk than those with a BMI of less than 21 kg/m(2) ("underweight") or 31 kg/m(2) or greater ("obese"). Both "underweight" and "obese" individuals had a greater risk of mortality compared with patients with "normal" BMI.
  
  
  CONCLUSIONS
  The U-shaped association of BMI with hospital mortality in geriatric AKI patients contains a widened base and a shifted nadir comparing with chronic dialysis and other AKI patients. This finding is interesting and warrants our attention.
authors.affiliation: *Department of Traumatology and †Division of Nephrology, Department of Internal Medicine, National Taiwan University Hospital, College of Medicine, National Taiwan University; ‡Division of Nephrology, Buddhist Tzu Chi General Hospital; and §National Taiwan University Hospital Study Group on Acute Renal Failure, Taipei, Taiwan.
authors.forename: Chia-Ter
authors.initials: CT
authors.lastname: Chao
authors.forename: Vin-Cent
authors.initials: VC
authors.lastname: Wu
authors.forename: Hung-Bin
authors.initials: HB
authors.lastname: Tsai
authors.forename: Che-Hsiung
authors.initials: CH
authors.lastname: Wu
authors.forename: Yu-Feng
authors.initials: YF
authors.lastname: Lin
authors.forename: Kuan-Dun
authors.initials: KD
authors.lastname: Wu
authors.forename: Wen-Je
authors.initials: WJ
authors.lastname: Ko
mesh_terms: D058186:Acute Kidney Injury / Q000453:epidemiology* / Q000401:mortality* / Q000473:pathology; D000368:Aged; D000369:Aged, 80 and over; D015992:Body Mass Index; D005260:Female; D006801:Humans; D008297:Male; D016016:Proportional Hazards Models; D012189:Retrospective Studies