title: Hyponatremia predicts mortality after stroke.
abstract: BACKGROUND
  Hyponatremia, the commonest electrolyte imbalance encountered in clinical practice, is associated with adverse outcomes. Despite this, understanding of the association between hyponatremia and stroke mortality outcome is limited.
  
  
  OBJECTIVE
  To investigate the association between admission serum sodium and mortality at various time-points after stroke.
  
  
  METHODS
  Cases of acute stroke admitted to Norfolk and Norwich University Hospital consecutively from January 2003 until June 2013 were included, with mortality outcomes ascertained until the end of December 2013. Odds ratios or hazards ratios for death were constructed for various time-points (within seven-days, 8-30 days, within one-year, and over full follow-up).
  
  
  RESULTS
  There were 8540 participants included (47·4% male, mean age 77·3 (±12·0) years). Point prevalence of hypernatremia and hyponatremia were 3·3% and 13·8%, respectively. In fully adjusted models controlling for age, gender, prestroke modified Rankin score, stroke type, Oxford community stroke project class, and laboratory biochemical and hematological results, the odds ratio (up to one-year)/hazards ratio (for full follow-up) for the above time-points were 1·00, 1·11, 1·03, 1·05 for mild hyponatremia; 1·97, 0·78, 1·11, 1·2 for moderate hyponatremia; 3·31, 1·57, 2·45, 1·67 for severe hyponatremia; and 0·47, 1·23, 1·30, 1·10 for hypernatremia. When stratified by age groups, outcomes were poorer in younger hyponatremic patients (aged <75 years).
  
  
  CONCLUSIONS
  Hyponatremia is prevalent in acute stroke admissions and is independently associated with higher mortality in patients <75 years.
authors.affiliation: Department of Geriatric Medicine, Aberdeen Royal Infirmary, Aberdeen, Scotland, UK.|School of Medicine & Dentistry, University of Aberdeen, Aberdeen, Scotland, UK.
authors.forename: Roy L
authors.initials: RL
authors.lastname: Soiza
authors.affiliation: School of Medicine & Dentistry, University of Aberdeen, Aberdeen, Scotland, UK.
authors.forename: Kirsten
authors.initials: K
authors.lastname: Cumming
authors.affiliation: Norwich Medical School, University of East Anglia, Norwich, Norfolk, UK.
authors.forename: Allan B
authors.initials: AB
authors.lastname: Clark
authors.affiliation: Stroke Research Group, Norfolk & Norwich University Hospital, Norwich, Norfolk, UK.
authors.forename: Joao H
authors.identifier: http://orcid.org/0000-0002-4562-0911
authors.initials: JH
authors.lastname: Bettencourt-Silva
authors.affiliation: Norwich Medical School, University of East Anglia, Norwich, Norfolk, UK.|Stroke Research Group, Norfolk & Norwich University Hospital, Norwich, Norfolk, UK.
authors.forename: Anthony K
authors.initials: AK
authors.lastname: Metcalf
authors.affiliation: Norwich Medical School, University of East Anglia, Norwich, Norfolk, UK.|Stroke Research Group, Norfolk & Norwich University Hospital, Norwich, Norfolk, UK.
authors.forename: Kristian M
authors.initials: KM
authors.lastname: Bowles
authors.affiliation: Norwich Medical School, University of East Anglia, Norwich, Norfolk, UK.|Stroke Research Group, Norfolk & Norwich University Hospital, Norwich, Norfolk, UK.
authors.forename: John F
authors.initials: JF
authors.lastname: Potter
authors.affiliation: Department of Geriatric Medicine, Aberdeen Royal Infirmary, Aberdeen, Scotland, UK.|School of Medicine & Dentistry, University of Aberdeen, Aberdeen, Scotland, UK.|Norwich Medical School, University of East Anglia, Norwich, Norfolk, UK.|Stroke Research Group, Norfolk & Norwich University Hospital, Norwich, Norfolk, UK.
authors.forename: Phyo K
authors.initials: PK
authors.lastname: Myint
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D005260:Female; D006801:Humans; D007010:Hyponatremia / Q000150:complications* / Q000453:epidemiology; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D012964:Sodium / Q000097:blood; D020521:Stroke / Q000175:diagnosis* / Q000453:epidemiology / Q000401:mortality* / Q000503:physiopathology; D013997:Time Factors
chemical_list: D012964:Sodium
keywords: dysnatremia; hyponatremia; outcomes; prognosis; sodium; stroke