Clin Respir J. 2021 Jun 7. doi: 10.1111/crj.13409. Online ahead of print.
INTRODUCTION: Hyponatremia is shown to prolong hospitalization and increase mortality. The role of hyponatremia in chronic obstructive pulmonary disease is widely studied with a focus on hospitalized patients.
OBJECTIVES: To investigate whether hyponatremia increases the probability of re-exacerbations in non-hospitalized patients with acute exacerbations of chronic obstructive pulmonary disease (AECOPD).
METHODS: Patients with AECOPD who required an emergency department (ED) visit and who were discharged home were included in this single-center, retrospective study. Demographics and laboratory values were compared between patients with hyponatremia (<135 mmol/L) and normonatremia (135-145 mmol/L). The predictors of the patients' ED revisit in the course of one-year were analyzed RESULTS: Of all the 3,274 patients, baseline sodium values were classified as hyponatremia in 720 (22%). Hyponatremia was most frequently present as mild (85%). Patients with hyponatremia had higher Charlson comorbidity scores, higher leucocytes, lower hemoglobin, lower platelet, higher neutrophil to lymphocyte ratios, lower eosinophilia, higher aspartate aminotransferase and C-reactive protein values (p<0.001, for all) and higher frequency of 1-month revisit (36.7% vs. 31.5%, p=0.009). Independent predictors of revisits within one year after the index visit were detected as long-term oxygen treatment (LTOT) requirement (HR:0.768 CI:0.695-0.848, p<0.0001), higher urea levels (HR:0.997 CI:0.995-0.999, p=0.003) and baseline hyponatremia (HR:0.786 CI:0.707-0.873, p<0.001). Revisit interval was median 78±3.4 days in patients with normonatremia and 51±4.8 days in hyponatremia.
CONCLUSION: In non-hospitalized AECOPD, hyponatremia is relatively frequent and correlates with inflammatory markers. The presence of hyponatremia is an independent predictor of an earlier ED return visit within one year. For patients with AECOPD, sodium values may present guidance on discharge vs. longer observation decisions.