Hyponatraemia is independently associated with in-hospital mortality in patients with pneumonia

Published:April 13, 2018DOI:


      • Hyponatraemia (<130 mmol/L) predicts poor outcome in patients admitted with pneumonia.
      • Hyponatraemia is an independent risk factor for hospital mortality and ICU admission.
      • Hyponatraemia on admission is not associated with length of hospitalisation.



      Hyponatraemia on hospital admission has been shown to be a risk factor for illness severity in critically ill patients. The aim of the present study was to investigate whether hyponatraemia on emergency department (ED) admission independently influences in-hospital mortality, ICU admission, and/or length of hospitalisation in patients with pneumonia.


      610 patients (64.4% male, median 66 years) diagnosed with pneumonia were identified by retrospective screening of electronic admission data (06/2011–06/2013). Patients were admitted to the ED of Bern University Hospital, Switzerland. Patient characteristics, potential confounders, and patient-centred clinical outcomes, including mortality, ICU admission, and length of hospitalisation, were analysed. Multivariate logistic analysis adjusted for typical confounders was performed to analyse the association of hyponatraemia with clinical outcomes.


      In a large cohort of consecutive acutely admitted patients with pneumonia, the overall in-hospital mortality rate was 12.5%; 21.2% of patients required primary or secondary ICU admission, and the median length of hospital stay was 8 (IQR 5–13) days. At baseline, 47 patients (7.7%) were found to have concomitant hyponatraemia. Multivariate regression revealed a significant association between hyponatraemia and in-hospital mortality (adjusted OR: 2.7, 95% CI: 1.3–5.9, p = 0.010), but not with ICU admission (adjusted OR: 1.8, 95% CI: 0.9–3.6, p = 0.103) or length of hospitalisation (p = 0.493) after adjustment for age, neoplasia, COPD, suspected sepsis, and cardiac disease. The association was robust if controlled for other covariates, e.g. CRB-65 score.


      Hyponatraemia on admission predicts poor outcome and is an independent risk factor for in-hospital mortality in admitted patients diagnosed with pneumonia.


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        • Corrado R.E.
        • Lee D.
        • Lucero D.E.
        • et al.
        Burden of adult community-acquired, healthcare-associated, hospital-acquired, and ventilator-associated pneumonia: New York City, 2010–2014.
        Chest. 2017; 152: 930-942
        • Gisby M.
        • Lundberg J.
        • Landin M.
        • et al.
        The burden of illness in patients with hyponatraemia in Sweden: a population-based registry study.
        Int J Clin Pract. 2016; 70: 319-329
        • Hawkins R.C.
        Age and gender as risk factors for hyponatremia and hypernatremia.
        Clin Chim Acta. 2003; 337: 169-172
        • Padhi R.
        • Panda B.N.
        • Jagati S.
        • et al.
        Hyponatremia in critically ill patients.
        Indian J Crit Care Med. 2014; 18: 83-87
        • Nair V.
        • Niederman M.S.
        • Masani N.
        • et al.
        Hyponatremia in community-acquired pneumonia.
        Am J Nephrol. 2007; 27: 184-190
        • Zilberberg M.D.
        • Exuzides A.
        • Spalding J.
        • et al.
        Hyponatremia and hospital outcomes among patients with pneumonia: a retrospective cohort study.
        BMC Pulm Med. 2008; 8: 16
        • Zilberberg M.D.
        • Exuzides A.
        • Spalding J.
        • et al.
        Epidemiology, clinical and economic outcomes of admission hyponatremia among hospitalized patients.
        Curr Med Res Opin. 2008; 24: 1601-1608
        • Boscoe A.
        • Paramore C.
        • Verbalis J.G.
        Cost of illness of hyponatremia in the United States.
        Cost Eff Resour Alloc. 2006; 4: 10
        • Callahan M.A.
        • Do H.T.
        • Caplan D.W.
        • et al.
        Economic impact of hyponatremia in hospitalized patients: a retrospective cohort study.
        Postgrad Med. 2009; 121: 186-191
        • Rhoney D.H.
        Cost and resource allocation issues in managing hyponatremia: the pharmacist's role.
        Pharmacotherapy. 2011; 31: 25S-30S
        • Knaus W.A.
        • Draper E.A.
        • Wagner D.P.
        • et al.
        APACHE II: a severity of disease classification system.
        Crit Care Med. 1985; 13: 818-829
        • Edmonds Z.V.
        Hyponatremia in pneumonia.
        J Hosp Med. 2012; 7: S11-3
        • Karki L.
        • Thapa B.
        • Sah M.K.
        Hyponatremia in patients with community acquired pneumonia.
        JNMA J Nepal Med Assoc. 2016; 54: 67-71
        • Exadaktylos A.K.
        • Hautz W.E.
        Emergency medicine in Switzerland.
        ICU Manage Pract. 2015; 15
        • Muller M.
        • Guignard V.
        • Schefold J.C.
        • et al.
        Utility of quick sepsis-related organ failure assessment (qSOFA) to predict outcome in patients with pneumonia.
        PLoS One. 2017; 12: e0188913
        • Lindner G.
        • Funk G.C.
        • Schwarz C.
        • et al.
        Hypernatremia in the critically ill is an independent risk factor for mortality.
        Am J Kidney Dis. 2007; 50: 952-957
        • O'Donoghue S.D.
        • Dulhunty J.M.
        • Bandeshe H.K.
        • et al.
        Acquired hypernatraemia is an independent predictor of mortality in critically ill patients.
        Anaesthesia. 2009; 64: 514-520
        • Almirall J.
        • Bolibar I.
        • Balanzo X.
        • et al.
        Risk factors for community-acquired pneumonia in adults: a population-based case-control study.
        Eur Respir J. 1999; 13: 349-355
        • Nagler E.V.
        • Vanmassenhove J.
        • van der Veer S.N.
        • et al.
        Diagnosis and treatment of hyponatremia: a systematic review of clinical practice guidelines and consensus statements.
        BMC Med. 2014; 12
        • Nair G.B.
        • Niederman M.S.
        Nosocomial pneumonia: lessons learned.
        Crit Care Clin. 2013; 29: 521-546
        • Bauer T.T.
        • Ewig S.
        • Marre R.
        • et al.
        CRB-65 predicts death from community-acquired pneumonia.
        J Intern Med. 2006; 260: 93-101
        • Kang C.I.
        • Chung D.R.
        • Peck K.R.
        • et al.
        Hyponatremia and predictive rules for prognosis in adult patients with community-acquired pneumonia.
        J Infect. 2010; 60: 503-505
        • Maldonado G.
        • Greenland S.
        Simulation study of confounder-selection strategies.
        Am J Epidemiol. 1993; 138: 923-936
        • Mickey R.M.
        • Greenland S.
        The impact of confounder selection criteria on effect estimation.
        Am J Epidemiol. 1989; 129: 125-137
        • Groenwold R.H.
        • Klungel O.H.
        • Grobbee D.E.
        • et al.
        Selection of confounding variables should not be based on observed associations with exposure.
        Eur J Epidemiol. 2011; 26: 589-593
        • Afifi A.
        • May S.
        • Clark V.A.
        Practical multivariate analysis.
        CRC Press, 2011
        • Zhang Z.
        Variable selection with stepwise and best subset approaches.
        Ann Transl Med. 2016; 4: 136
        • Fine M.J.
        • Auble T.E.
        • Yealy D.M.
        • et al.
        A prediction rule to identify low-risk patients with community-acquired pneumonia.
        N Engl J Med. 1997; 336: 243-250
        • Zhang Y.Y.
        • Zhou X.B.
        • Wang Q.Z.
        • et al.
        Quality of reporting of multivariable logistic regression models in Chinese clinical medical journals.
        Medicine. 2017; 96: e6972
        • Chalmers J.D.
        ICU admission and severity assessment in community-acquired pneumonia.
        Crit Care. 2009; 13: 156