Incidence of hospital-acquired hyponatremia by the dose and type of diuretics among patients with acute heart failure and its association with long-term outcomes.

BACKGROUND: Diuretics are the cornerstone therapy for acute heart failure (AHF) but can lead to various electrolyte disturbances and inversely affect the patients' outcome. We aimed to evaluate whether (1) the dose of loop diuretics could predict hospital-acquired hyponatremia (HAH) during AHF treatment, (2) addition of thiazide diuretics could affect development of HAH, and (3) assess their impact on long-term outcomes.

METHODS: We analyzed the subjects enrolled in the multicenter AHF registry (WET-HF). Risk of HAH, defined as hyponatremia at discharge with normonatremia upon admission, was evaluated based on oral non-potassium-sparing diuretics via multivariate logistic regression analysis. Additionally, we performed one-to-one matched analysis based on propensity scores for thiazide diuretics use and compared long-term mortality.

RESULTS: Of total 1163 patients (mean age 72.6±13.6 years, male 62.6%), 92 (7.9%) had HAH. Compared with low-dose loop diuretics users (<40mg; without thiazide diuretics), risks for developing HAH were significantly higher in patients with thiazide diuretics, regardless of the dose of loop diuretics (OR 2.67, 95% CI 1.13-6.34 and OR 2.31, 95% CI 1.50-5.13 for low- and high-dose loop diuretics, respectively). The association was less apparent in patients without thiazide diuretics (OR 1.29, 95% CI 0.73-2.27 for high-dose loop diuretics alone). Among 206 matched patients, all-cause and cardiac mortality rate was 27% and 14% in non thiazide diuretics users and 50% and 30% in thiazide diuretics users, respectively (HR 2.46, 95% CI 1.29-4.69, p=0.006 and HR 2.50, 95% CI 1.10-5.67, p=0.028, respectively) during a mean 19.3 months of follow-up.

CONCLUSIONS: Thiazide diuretics use, rather than loop diuretics dose, was independently associated with HAH; and mortality was higher in thiazide diuretics users even after statistical matching.