Impact of Hyponatraemia at Clinical Stable-State on Survival in Patients with Chronic Obstructive Pulmonary Disease

Int J Chron Obstruct Pulmon Dis. 2025 Jan 15:20:127-135. doi: 10.2147/COPD.S488309. eCollection 2025.

Abstract

Introduction: Hyponatraemia has been suggested to be associated with morbidity and mortality among various medical disorders. Evidence on the association between stable-state hyponatraemia and prognosis in patients with chronic obstructive pulmonary disease (COPD) is lacking.

Methods: All COPD patients followed up in a regional hospital in year 2015 were included, with their clinical outcomes reviewed in the subsequent eight years. Association between stable-state hyponatraemia and mortality was evaluated. Stable-state hyponatraemia is defined as baseline serum sodium levels, at least 90 days away from the last AECOPD <135 mmol/L.

Results: There were 271 COPD patients included. Hyponatraemia was associated with shorter overall survival with adjusted hazard ratio (aHR) 1.74 (95% CI = 1.07-2.65, p = 0.026). The median overall survival was 3.05 years (95% CI = 2.65-3.46) for patients in the hyponatraemia group, in contrast to 3.35 years (95% CI = 2.86-3.83) for those without hyponatraemia. The highest baseline serum sodium levels were significantly negatively associated with annual acute exacerbation of COPD (AECOPD) and annual hospitalized AECOPD frequency in the follow-up period, with Pearson correlation coefficient of -0.16 (p = 0.011) and - 0.14 (p = 0.027), respectively.

Conclusion: Stable-state hyponatraemia was associated with increased mortality and probably AECOPD frequency among patients with COPD.

Keywords: acute exacerbation of chronic obstructive pulmonary disease; chronic obstructive pulmonary disease; electrolyte; hyponatraemia; sodium.

MeSH terms

  • Aged
  • Aged, 80 and over
  • Biomarkers* / blood
  • Disease Progression*
  • Female
  • Humans
  • Hyponatremia* / blood
  • Hyponatremia* / diagnosis
  • Hyponatremia* / mortality
  • Kaplan-Meier Estimate
  • Male
  • Middle Aged
  • Prognosis
  • Proportional Hazards Models
  • Pulmonary Disease, Chronic Obstructive* / blood
  • Pulmonary Disease, Chronic Obstructive* / complications
  • Pulmonary Disease, Chronic Obstructive* / diagnosis
  • Pulmonary Disease, Chronic Obstructive* / mortality
  • Retrospective Studies
  • Risk Factors
  • Sodium* / blood
  • Time Factors

Substances

  • Sodium
  • Biomarkers