title: Augmented renal clearance in the ICU: results of a multicenter observational study of renal function in critically ill patients with normal plasma creatinine concentrations*.
abstract: OBJECTIVE
  To describe the prevalence and natural history of augmented renal clearance in a cohort of recently admitted critically ill patients with normal plasma creatinine concentrations.
  
  
  METHODS
  Multicenter, prospective, observational study.
  
  
  METHODS
  Four, tertiary-level, university-affiliated, ICUs in Australia, Singapore, Hong Kong, and Portugal.
  
  
  METHODS
  Study participants had to have an expected ICU length of stay more than 24 hours, no evidence of absolute renal impairment (admission plasma creatinine < 120 µmol/L), and no history of prior renal replacement therapy or chronic kidney disease. Convenience sampling was used at each participating site.
  
  
  METHODS
  Eight-hour urinary creatinine clearances were collected daily, as the primary method of measuring renal function. Augmented renal clearance was defined by a creatinine clearance more than or equal to 130 mL/min/1.73 m. Additional demographic, physiological, therapeutic, and outcome data were recorded prospectively.
  
  
  RESULTS
  Nine hundred thirty-two patients were admitted to the participating ICUs over the study period, and 281 of which were recruited into the study, contributing 1,660 individual creatinine clearance measures. The mean age (95% CI) was 54.4 years (52.5-56.4 yr), Acute Physiology and Chronic Health Evaluation II score was 16 (15.2-16.7), and ICU mortality was 8.5%. Overall, 65.1% manifested augmented renal clearance on at least one occasion during the first seven study days; the majority (74%) of whom did so on more than or equal to 50% of their creatinine clearance measures. Using a mixed-effects model, the presence of augmented renal clearance on study day 1 strongly predicted (p = 0.019) sustained elevation of creatinine clearance in these patients over the first week in ICU.
  
  
  CONCLUSIONS
  Augmented renal clearance appears to be a common finding in this patient group, with sustained elevation of creatinine clearance throughout the first week in ICU. Future studies should focus on the implications for accurate dosing of renally eliminated pharmaceuticals in patients with augmented renal clearance, in addition to the potential impact on individual clinical outcomes.
authors.affiliation: 1Burns, Trauma, and Critical Care Research Centre, The University of Queensland, Royal Brisbane and Women's Hospital, Herston, QLD, Australia. 2Department of Intensive Care Medicine, Royal Brisbane and Women's Hospital, Herston, QLD, Australia. 3Serviço de Medicina Intensiva, Hospitais da Universidade de Coimbra, EPE Praceta Prof. Mota Pinto, Coimbra, Portugal. 4Anaesthesia and Surgical Intensive Care, Changi General Hospital, Singapore. 5Department of Anaesthesia and Intensive Care, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin NT, Hong Kong SAR. 6Statistics Unit, Level 3 Clive Berghofer Cancer Research Centre, Queensland Institute of Medical Research, Herston, QLD, Australia.
authors.forename: Andrew A
authors.initials: AA
authors.lastname: Udy
authors.forename: João P
authors.initials: JP
authors.lastname: Baptista
authors.forename: Noelle L
authors.initials: NL
authors.lastname: Lim
authors.forename: Gavin M
authors.initials: GM
authors.lastname: Joynt
authors.forename: Paul
authors.initials: P
authors.lastname: Jarrett
authors.forename: Leesa
authors.initials: L
authors.lastname: Wockner
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Boots
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Lipman
mesh_terms: D058186:Acute Kidney Injury / Q000175:diagnosis* / Q000401:mortality / Q000517:prevention & control; D000328:Adult; D000368:Aged; D001315:Australia; D016001:Confidence Intervals; D003404:Creatinine / Q000097:blood*; D016638:Critical Illness / Q000401:mortality / Q000628:therapy; D005260:Female; D006723:Hong Kong; D017052:Hospital Mortality / Q000639:trends*; D006785:Hospitals, University; D006801:Humans; D007362:Intensive Care Units; D007677:Kidney Function Tests; D007902:Length of Stay; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000379:methods; D011174:Portugal; D011379:Prognosis; D011446:Prospective Studies; D012016:Reference Values; D018570:Risk Assessment; D012846:Singapore; D018709:Statistics, Nonparametric
chemical_list: D003404:Creatinine