Association between hypernatraemia acquired in the ICU and mortality: a cohort study.
BACKGROUND
The aim of this study is to describe the prevalence and outcomes of intensive care unit (ICU)-acquired hypernatraemia (IAH).


METHODS
A retrospective analysis was performed on a prospectively collected database fed by 12 ICUs. Subjects are unselected patients with ICU stay >48 h. Mild and moderate to severe hypernatraemia were defined as serum sodium >145 and >150 mmol/L, respectively. IAH was hypernatraemia occurring >or=24 h after ICU admission in patients with normal serum sodium at ICU admission.


RESULTS
Of the 8441 patients, 301 were excluded because they had hypernatraemia at ICU admission. Of the remaining 8140 patients, 901 (11.1%) experienced mild hypernatraemia, and 344 (4.2%) experienced moderate to severe hypernatraemia. Factors independently associated with IAH were male gender, severity at admission as assessed by the Simplified Acute Physiology Score version II (SAPS II), and organ failure or life-supporting treatment at ICU admission. Unadjusted hospital mortality was 15.2% in patients without hypernatraemia compared to 29.5% in patients with mild IAH and 46.2% in those with moderate to severe IAH (P < 0.0001). When any degree of IAH was handled as a time-dependent variable in a subdistribution hazard model, the subdistribution hazard ratio (SHR) for ICU mortality was 4.26 [95% confidence interval (CI), 3.74-4.84]. After stratification by centre and adjustment for confounders, both mild IAH and moderate to severe IAH were independently associated with mortality [SHR 2.03 (95% CI 1.73-2.39) and 2.67 (95% CI 2.19-3.26), respectively].


CONCLUSIONS
IAH is frequent and associated with mortality after adjustment on severity at ICU admission.
Darmon
Michael
M
Medical Intensive Care Unit, Saint-Louis University Hospital, APHP, 1 Avenue Claude Vellefaux, Paris, France. michael.darmon@chu-st-etienne.fr
Timsit
Jean-François
JF
Francais
Adrien
A
Nguile-Makao
Molière
M
Adrie
Christophe
C
Cohen
Yves
Y
Garrouste-Orgeas
Maïté
M
Goldgran-Toledano
Dany
D
Dumenil
Anne-Sylvie
AS
Jamali
Samir
S
Cheval
Christine
C
Allaouchiche
Bernard
B
Souweine
Bertrand
B
Azoulay
Elie
E
D000368:Aged; D015331:Cohort Studies; D005260:Female; D017052:Hospital Mortality; D006801:Humans; D006955:Hypernatremia / Q000175:diagnosis* / Q000453:epidemiology / Q000209:etiology*; D007362:Intensive Care Units; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011379:Prognosis; D011446:Prospective Studies; D012189:Retrospective Studies; D012307:Risk Factors; D012720:Severity of Illness Index; D012727:Sex Characteristics; D012964:Sodium / Q000097:blood; D015996:Survival Rate
D012964:Sodium