Hyponatremia is an independent predictor of emergency department revisits in acute exacerbation of COPD

Risk factors for hyponatremia in acute exacerbation chronic obstructive pulmonary disease (AECOPD): a multicenter cross-sectional study

BACKGROUND

Hyponatremia is an independent predictor of poor prognosis, including increased mortality and readmission, in COPD patients. Identifying modifiable etiologies of hyponatremia may help reduce adverse events in patients with AECOPD. Therefore, the aim of this study was to explore the risk factors and underlying etiologies of hyponatremia in AECOPD patients.

METHODS

A total of 586 AECOPD patients were enrolled in this multicenter cross-sectional study. Finally, 323 had normonatremia, and 90 had hyponatremia. Demographics, underlying diseases, comorbidities, symptoms, and laboratory data were collected. The least absolute shrinkage and selection operator (LASSO) regression was used to select potential risk factors, which were substituted into binary logistic regression to identify independent risk factors. Nomogram was built to visualize and validate binary logistics regression model.

RESULTS

Nine potential hyponatremia-associated variables were selected by LASSO regression. Subsequently, a binary logistic regression model identified that smoking status, rate of community-acquired pneumonia (CAP), anion gap (AG), erythrocyte sedimentation rate (ESR), and serum magnesium (Mg²⁺) were independent variables of hyponatremia in AECOPD patients. The AUC of ROC curve of nomogram was 0.756. The DCA curve revealed that the nomogram could yielded more clinical benefits if the threshold was between 10% and 52%.

CONCLUSIONS

Collectively, our results showed that smoking status, CAP, AG, ESR, and serum Mg²⁺ were independently associated with hyponatremia in AECOPD patients. Then, these findings indicate that pneumonia, metabolic acidosis, and hypomagnesemia were the underlying etiologies of hyponatremia in AECOPD patients. However, their internal connections need further exploration.

Sodium and potassium disorders in patients with COPD exacerbation presenting to the emergency department

Background

Electrolyte disorders are common in the emergency department. Hyponatremia is known to be associated with adverse outcome in community-acquired pneumonia (CAP) and acute exacerbation of chronic obstructive pulmonary disease (AECOPD). No studies investigating the prevalence and influence of hypernatremia or potassium disorders in patients with AECOPD exist.

Methods

In this retrospective cohort analysis, the prevalence of sodium and potassium disorders was investigated in patients with AECOPD presenting to an emergency department (ED) between January 1^st 2017 and December 31^st 2018 and compared to all ED patients with electrolyte measurements and patients presenting with CAP. Exclusion criteria were age younger than 18 years, written or verbal withdrawal of consent and outpatient treatment. Additionally, the influence of dysnatremias and dyskalemias on outcome measured by ICU admission, need for mechanical ventilation, length of hospital stay, 30-day re-admission, 180-day AECOPD recurrence and in-hospital mortality and their role as predictors of disease severity measured by Pneumonia Severity Index (PSI) were investigated in patients with AECOPD.

Results

Nineteen point nine hundred forty-eight ED consultations with measurements of sodium and potassium were recognized between January 1^st 2017 and December 31^st 2018 of which 102 patients had AECOPD. Of these 23% had hyponatremia, 5% hypernatremia, 16% hypokalemia and 4% hyperkalemia on admission to the ED. Hypo- and hypernatremia were significantly more common in patients with AECOPD than in the overall ED population: 23 versus 11% (p = 0.001) for hypo- and 5% versus 0.6% (p < 0.001) for hypernatremia. In the logistic regression analysis, no association between the presence of either sodium or potassium disorders and adverse outcome were found.

Conclusion

Dysnatremias and dyskalemias are common in patients with AECOPD with as many as 1 in 5 having hyponatremia and/or hypokalemia. Hypo- and hypernatremia were significantly more common in AECOPD than overall. No significant association was found for dysnatremias, dyskalemias and adverse outcomes in AECOPD.