Stable-State Hyponatraemia Linked to Increased Mortality and Exacerbations in COPD Patients: Study Finds

The findings suggest that COPD patients with stable-state hyponatraemia are at an increased risk of mortality. The research, which tracked 271 COPD patients over eight years, revealed that those with serum sodium levels below 135 mmol/L had a shorter overall survival (3.05 years versus 3.35 years), with a hazard ratio (HR) of 1.74. Furthermore, higher sodium levels were associated with fewer annual episodes of acute exacerbations and hospitalizations due to COPD.

Hyponatraemia is often considered a marker of underlying health issues and has been previously linked to poor outcomes in several chronic diseases. However, its role in COPD patients, particularly during periods when the disease is clinically stable, has not been thoroughly explored until now. To fill this knowledge gap, The University of Hong Kong, Pokfulam, Hong Kong SAR, People’s Republic of China, and colleagues aimed to examine the effect of stable-state hyponatraemia on survival and the frequency of future exacerbations in patients with COPD.

For this purpose, the researchers included all COPD patients who were followed up at a regional hospital in 2015, reviewing their clinical outcomes over the next eight years. The study assessed the association between stable-state hyponatraemia and mortality. Stable-state hyponatraemia was defined as baseline serum sodium levels below 135 mmol/L, measured at least 90 days after the last acute exacerbation of COPD (AECOPD).

Key Findings:

• The study included 271 COPD patients.
• Hyponatraemia was linked to shorter overall survival, with an adjusted hazard ratio (aHR) of 1.74.
• The median overall survival was 3.05 years for patients with hyponatraemia, compared to 3.35 years for those without hyponatraemia.
• Higher baseline serum sodium levels were significantly associated with fewer annual acute exacerbations of COPD and fewer hospitalizations due to AECOPD during the follow-up period.
• Pearson correlation coefficients for the associations were −0.16 for annual AECOPD frequency and −0.14 for hospitalized AECOPD frequency.

The findings revealed that stable-state hyponatraemia is a common electrolyte imbalance in COPD, affecting 16.2% of patients. It is linked to higher mortality rates and potentially increased frequency of acute exacerbations of COPD. Regular monitoring of serum sodium levels and timely correction may help reduce mortality and exacerbation risk in COPD patients.

"Our findings further highlight the negative impact of stable-state hyponatraemia, showing its association with higher mortality and potentially increased frequency of subsequent AECOPD. These results emphasize the need for regular monitoring of serum sodium levels in COPD patients and suggest that proactive management of hyponatraemia is crucial for improving patient outcomes," the researchers concluded.

Reference:

Kwok WC, Yap DYH, Tam TCC, Lam DCL, Ip MSM, Ho JCM. Impact of Hyponatraemia at Clinical Stable-State on Survival in Patients with Chronic Obstructive Pulmonary Disease. Int J Chron Obstruct Pulmon Dis. 2025;20:127-135. https://doi.org/10.2147/COPD.S488309