Hyponatremia and hospital outcomes among patients with pneumonia: a retrospective cohort study.
BACKGROUND
Community-acquired (CAP) and nosocomial pneumonias contribute substantially to morbidity and hospital resource utilization. Hyponatremia, occurring in >1/4 of patients with CAP, is associated with greater disease severity and worsened outcomes.


METHODS
To explore how hyponatremia is associated with outcomes in hospitalized patients with pneumonia, we analyzed a large administrative database with laboratory component from January 2004 to December 2005. Hyponatremia was defined as at least two [Na+] < 135 mEq/L within 24 hours of admission value.


RESULTS
Of 7,965 patients with pneumonia, 649 (8.1%) with hyponatremia were older (72.4 +/- 15.7 vs. 68.0 +/- 22.0, p < 0.01), had a higher mean Deyo-Charlson Comorbidity Index Score (1.7 +/- 1.7 vs. 1.6 +/- 1.6, p = 0.02), and higher rates of ICU (10.0% vs. 6.3%, p < 0.001) and MV (3.9% vs. 2.3%, p = 0.01) in the first 48 hours of hospitalization than patients with normal sodium. Hyponatremia was associated with an increased ICU (6.3 +/- 5.6 vs. 5.3 +/- 5.1 days, p = 0.07) and hospital lengths of stay (LOS, 7.6 +/- 5.3 vs. 7.0 +/- 5.2 days, p < 0.001) and a trend toward increased hospital mortality (5.4% vs. 4.0%, p = 0.1). After adjusting for confounders, hyponatremia was associated with an increased risk of ICU (OR 1.58, 95% CI 1.20-2.08), MV (OR 1.75 95% CI 1.13-2.69), and hospital death (OR 1.3, 95% CI 0.90-1.87) and with increases of 0.8 day to ICU and 0.3 day to hospital LOS, and over $1,300 to total hospital costs.


CONCLUSIONS
Hyponatremia is common among hospitalized patients with pneumonia and is associated with worsened clinical and economic outcomes. Studies in this large population are needed to explore whether prompt correction of [Na+] may impact these outcomes.
Zilberberg
Marya D
MD
Evi Med Research Group, LLC, Goshen, Massachusetts, USA. MZilberb@schoolph.umass.edu.
Exuzides
Alex
A
Spalding
James
J
Foreman
Aimee
A
Jones
Alison Graves
AG
Colby
Chris
C
Shorr
Andrew F
AF
D000368:Aged; D000369:Aged, 80 and over; D017714:Community-Acquired Infections; D015897:Comorbidity; D017052:Hospital Mortality; D006801:Humans; D007010:Hyponatremia / Q000453:epidemiology*; D007902:Length of Stay; D008297:Male; D008875:Middle Aged; D011014:Pneumonia / Q000453:epidemiology*; D012189:Retrospective Studies