NOCDURNA PASS Study Using Registries in Denmark, Germany and Sweden

Symptomatic hyponatraemia was defined as a primary or secondary diagnosis of hyponatraemia.

Hyponatraemia requiring hospital intensive care was defined as a primary or secondary diagnosis of hyponatraemia recorded in an intensive care unit.

Clinically significant hyponatraemia was defined as a serum sodium concentration of <130 mmol/L. Severity of hyponatraemia was categorized as mild hyponatraemia (serum sodium concentration: 130 to <135 mmol/L), moderate hyponatraemia (serum sodium concentration: >125 to <130 mmol/L) and severe hyponatraemia (serum sodium concentration: less than equal to [≤]125 mmol/L).

All-cause mortality was defined as death from any cause.

Major adverse cardiovascular events were defined as a record of myocardial infarction and stroke. Fatal and non-fatal events will be considered separately.

Venous thromboembolic events were defined as a record of a deep vein thrombosis, pulmonary embolism or portal vein thrombosis. Fatal and non-fatal events will be considered separately.

Acute exacerbation of congestive heart failure was defined as primary diagnosis of acute or acute-on-chronic heart failure from hospital inpatient care or the acute and emergency ward, or death from heart failure as the underlying or contributory cause.