Hypernatremia and risk of death in patients hospitalized for community acquired pneumonia: findings from the FADOI-ICECAP study

Introduction: Community-acquired pneumonia (CAP) is a frequent cause of admission to internal medicine units (IMUs). CAP-mortality is still high and it is necessary to identify possible risk factors for unfavorable outcomes. In this study we evaluated the effect of hypernatremia on mortality and the need for intensive care admission in CAP-patients admitted to internal medicine units (IMUs). Methods: We included 1241 patients hospitalized for CAP in 26 Italian IMUs from October 2016 to February 2018. Univariate and multivariate analyses were performed to evaluate the association between patients’ clinical characteristic, disease severity and sodium disorders with need for ICU admission and 30-day mortality . Results: The prevalence of hypernatremia was 5.7% (95%, CI: 4.41-6.99) and was significantly associated with 30-day mortality (OR 3.88, 95% CI 2.18-6.90) while no association with need for ICU admission was found. Other variables associated with 30-day mortality were age >75 years (OR 3.11, 95 CI 1.81-5.35); multilobar infiltrates at chest imaging (1.54, 95% CI 1.03-2.32); cancer (OR 6.32, 95% CI 3.22-12.4); dementia (OR 2.78, 95% CI 1.80-4.31) and chronic kidney disease (OR 1.70, 95% CI 1.03-2.80). Mortality in patients with 0, 1, 2, 3, or ≥ 4 risk factors progressively increased. Based on the number of risk factors in each patient we defined three risk categories that defined the short-term prognosis of this cohort better than PSI and CURB-65 (AUC 0.71 vs 0.63 and 0.64 respectively). Conclusions: Our study suggests a strong association between hypernatremia and adverse outcomes in patients with CAP. Further studies are needed to validate our score in clinical practice.