Hyponatremia and lower normal serum sodium levels are associated with an increased risk of all-cause death in heart failure patients.
Lang Zhao, Xuemei Zhao, Xiaofeng Zhuang and 11 others
PMID 36929057WHAT IT FOUND
Hospitalized heart failure patients with sodium below 135 mmol/L, or 135 to 137 mmol/L, had higher all-cause mortality during follow-up than those with 139 to 141 mmol/L.
Nurses may use admission sodium to flag higher-risk patients for closer monitoring.
Key findings
01In 3649 hospitalized heart failure patients, 1413 (38.7%) died during a median follow-up of 1101 days.
02Abnormal admission serum sodium, defined as <135 or >145 mmol/L, was associated with higher adjusted all-cause mortality than normal sodium (HR 1.58, 95% CI 1.32-1.89).
03Sodium levels of 135 to 137 mmol/L were associated with higher adjusted all-cause mortality than 139 to 141 mmol/L.
STILL TO COME
How it was doneWhat they foundWhat it means for RNs
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What it does not show
The study included only patients at one hospital heart failure unit, so the results may not apply to other settings. It was a retrospective record review, so factors not measured could explain part or all of the association. 863 patients were lost to follow-up, which could bias the mortality results. Patients who died during hospitalization were excluded, and hypernatremia was rare (53 patients), so the study cannot show hypernatremia raises post-discharge mortality. The study did not track serum sodium changes over time, so it cannot say whether sodium correction or sodium instability affected mortality. Only all-cause death was measured, not causes of death, and sodium chloride interaction was not examined.
Declared interests
The work was supported by Chinese government research grants and the CAMS Innovation Fund for Medical Science. The authors declared no competing financial interests or personal relationships that could have influenced the work.
The easy way to misread this
Do not conclude that treating low sodium will prevent death. The study is observational and only shows an association between admission sodium and later all-cause death; it did not test sodium correction.