The most common electrolyte disorder among hospitalized patients, hyponatremia is a predictor of poor prognosis in various diseases. The aim of this study was to establish the prevalence of hyponatremia in patients admitted for acute exacerbation of chronic obstructive pulmonary disease (AECOPD), as well as its association with poor clinical progress. Prospective observational study carried out from 1 October 2016 to 1 October 2018 in the following hospitals: Salnés in Vilagarcía de Arousa, Arquitecto Marcide in Ferrol, and the University Hospital Complex of Santiago de Compostela, Galicia, Spain, on patients admitted for AECOPD. Patient baseline treatment was identified, including hyponatremia-inducing drugs. Poor progress was defined as follows: prolonged stay, death during hospitalization, or readmission within one month after the index episode discharge. 602 patients were enrolled, 65 cases of hyponatremia (10.8%) were recorded, all of a mild nature (mean 131.6; SD 2.67). Of all the patients, 362 (60%) showed poor progress: 18 (3%) died at admission; 327 (54.3%) had a prolonged stay; and 91 (15.1%) were readmitted within one month after discharge. Patients with hyponatremia had a more frequent history of atrial fibrillation (AF) (p 0.005), pleural effusion (p 0.01), and prolonged stay (p 0.01). The factors independently associated with poor progress were hyponatremia, pneumonia, and not receiving home O2 treatment prior to admission. Hyponatremia is relatively frequent in patients admitted for AECOPD, and it has important prognostic implications, even when mild in nature.
Keywords: COPD; hyponatremia; prognosis.