[Hyponatremia on admission to the emergency room as a risk factor for hospital mortality].
BACKGROUND
Patients who develop hyponatremia during their hospitalization have higher hospital mortality.


OBJECTIVE
To determine if the presence of hyponatremia on admission to the emergency room is a risk factor for hospital mortality.


METHODS
Two hundred forty five patients consecutively admitted to the emergency room and then transferred to the Medicine Department, where they finally died, were matched for age and gender with 245 control subjects admitted to the emergency room and hospitalized in the Medicine Department at the same time, but survived. The dependent variable was death, and the exposure variable was hyponatremia. Admission diagnosis and Charlson comorbidity index was considered as confounding variables.


RESULTS
Hyponatremia at admission occurred in 30 and 17% of patients who died and survived, respectively, rendering an adjusted odds ratio for death of 2.13 (95% confidence intervals = 1.27-3.57). Charlson Comorbidity Index according to age score was higher in subjects with hyponatremia compared to those without hyponatremia (8.1 ± 3.1 and 7.2 ± 2.8; p = 0.01). Multivariate analysis showed that age, gender, length of stay, cause of hospitalization and chronic diseases did not significantly modify the effect of hyponatremia on hospital mortality.


CONCLUSIONS
Hyponatremia on admission at emergency room had a significant association with hospital mortality. Subjects with hyponatremia had a higher Charlson Comorbidity Index score.
Servicio de Medicina Interna, Sección de Nefrología, Hospital Naval A. Nef, Viña del Mar, Chile. jvegastieb@gmail.com
Jorge
J
Vega
Francisco
F
Manríquez
Eva
E
Madrid
Helmuth
H
Goecke
Alejandra
A
Carrasco
Gonzalo
G
Martínez
Alejandro
A
Joyas
Fernando
F
Rojas
Julio
J
Salinas
Hernán
H
Borja
D000368:Aged; D000369:Aged, 80 and over; D002677:Chile / Q000453:epidemiology; D015897:Comorbidity; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data*; D004812:Epidemiologic Methods; D005260:Female; D017052:Hospital Mortality; D006801:Humans; D007010:Hyponatremia / Q000401:mortality*; D008297:Male; D010343:Patient Admission / Q000706:statistics & numerical data; D012307:Risk Factors