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.
Conclusion: 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.