title: Incidence and prognosis of dysnatraemia in critically ill patients: analysis of a large prevalence study.
abstract: BACKGROUND
  The objective of this study is to assess the impact of dysnatraemia on mortality among intensive care unit (ICU) patients in a large, international cohort.
  
  
  METHODS
  Analysis of the Extended Prevalence of Infection in Intensive Care (EPIC II) study, a 1-day (8 May 2007) worldwide multicenter, prospective point prevalence study. Hyponatraemia was categorized as mild (130-134 mM/L), moderate (125-129 mM/L) or severe (< 125 mM/L). Hypernatraemia was also categorized as mild (146-150 mM/L), moderate (151-155 mM/L) or severe (> 155 mM/L). Patients with normal serum sodium (135-145 mM/L) constituted the reference group. The main outcome was hospital mortality. Analysis was conducted separately for patients admitted on the study day (25.8%) and those already present on the ICU (74.2%).
  
  
  RESULTS
  Serum sodium was measured in 13 276 of the 13 796 patients (96.2%). A total of 3815 patients (28.7%) had dysnatraemia: 12.9% with hyponatraemia and 15.8% with hypernatraemia. The prevalence of dysnatraemia was significantly greater in patients already present on the ICU prior to the study day than for those just admitted (13.1% vs. 12.3% for hyponatraemia and 17.1% vs. 12.1% for hypernatraemia, both P < 0.001). Hospital mortality rates were higher in patients with dysnatraemia than in those with normal sodium levels and were directly related to the severity of hypo- and hypernatraemia. This association between dysnatraemia and mortality was similar in infected and noninfected patients (P = 0.061).
  
  
  CONCLUSIONS
  Dysnatraemia is more frequent during the ICU stay than on the day of admission. Dysnatraemia in the ICU - even mild - is an independent predictor of increased hospital mortality.
authors.affiliation: Department of General Internal Medicine, Erasme Hospital, Université libre de Bruxelles, Belgium. fvdgheyn@ulb.ac.be
authors.forename: Frédéric
authors.initials: F
authors.lastname: Vandergheynst
authors.forename: Yasser
authors.initials: Y
authors.lastname: Sakr
authors.forename: Peter
authors.initials: P
authors.lastname: Felleiter
authors.forename: Rudolf
authors.initials: R
authors.lastname: Hering
authors.forename: Johan
authors.initials: J
authors.lastname: Groeneveld
authors.forename: Philippe
authors.initials: P
authors.lastname: Vanhems
authors.forename: Fabio S
authors.initials: FS
authors.lastname: Taccone
authors.forename: Jean-Louis
authors.initials: JL
authors.lastname: Vincent
mesh_terms: D003422:Critical Care / Q000706:statistics & numerical data; D016638:Critical Illness / Q000401:mortality; D004812:Epidemiologic Methods; D005260:Female; D014943:Global Health; D006801:Humans; D006955:Hypernatremia / Q000401:mortality*; D007010:Hyponatremia / Q000401:mortality*; D007902:Length of Stay; D008297:Male; D008875:Middle Aged; D011379:Prognosis
keywords: Hypernatraemia; hyponatraemia; intensive care; propensity score; sodium