Hyponatremia and in-hospital outcomes of patients admitted for heart failure: analysis of the national inpatient sample

Background

Hyponatremia serves as a well established predictor of mortality for advanced heart failure (1). The aim of this study is to reassess the association between hyponatremia and in-hospital outcomes in patients with acute decompensated heart failure (ADHF) by using a nationally representative sample.

Methods

We queried the National Inpatient Sample (NIS) database collected between 2016 and 2018 to identify patients with a primary diagnosis of HF and stratified the cohort on the basis of presence or absence of hyponatremia. The outcomes of interest included in-hospital mortality, common associated complications and usage of circulatory support.

Results

Among 727,629 hospital admissions for HF, 72,824 (10%) of them had an additional diagnosis of hyponatremia. The hyponatremia cohort appeared similar in age and had similar rates of Charlson comorbidity index greater than 4 (71 years vs 72 years and 33% vs 35%, respectively) compared to the non-hyponatremia cohort. The comorbidities more prevalent in patients with hyponatremia included: hypothyroidism (17% vs 21%, p<0.001), liver disease (4% vs 11%, p<0.001) and anemia (31% vs 42, p<0.001). By contrast, dyslipidemia, chronic obstructive pulmonary disease, chronic kidney disease, hypertension, diabetes mellitus, obesity, smoking status and supplemental oxygen use were comparable in both groups. ADHF patients with hyponatremia did not have higher odds of in-hospital mortality (aOR: 1.08, 95% CI: 0.98–1.19, p=0.138) when adjusted for comorbidities. Nevertheless, patients with hyponatremia had an adjusted increase in mean hospital charges of 14,731 US$ (95% CI: 11065–18397, p<0.001), length of stay by 2.6 days (95% CI: 2.5–2.8, p<0.001), usage of intra-aortic balloon pump (aOR: 1.97, 95% CI: 1.50–2.59, p<0.001) and left ventricular assist device (aOR: 2.21, 95% CI: 1.639–2.98, p<0.001), and higher incidence of acute renal failure (aOR: 1.13, 95% CI: 1.08–1.189, p<0.001) and cardiogenic shock (aOR: 1.58, 95% CI: 1.42–1.76, p<0.001) in comparison to patients without hyponatremia.

Conclusion

Multiple clinical variables excluded in the NIS dataset could have impacted the primary outcome. Clinicians who observe hyponatremia in ADHF patients should stay wary of potential side effects and maintain a low threshold to escalate care.

Funding Acknowledgement

Type of funding sources: None.

Axon diameter and axonal transport: In vivo and in vitro effects of androgens

Testosterone is a sex hormone involved in brain maturation via multiple molecular mechanisms. Previous human studies described age-related changes in the overall volume and structural properties of white matter during male puberty. Based on this work, we have proposed that testosterone may induce a radial growth of the axon and, possibly, modulate axonal transport. In order to determine whether this is the case we have used two different experimental approaches. With electron microscopy, we have evaluated sex differences in the structural properties of axons in the corpus callosum (splenium) of young rats, and tested consequences of castration carried out after weaning. Then we examined in vitro the effect of the non-aromatizable androgen Mibolerone on the structure and bidirectional transport of wheat-germ agglutinin vesicles in the axons of cultured sympathetic neurons. With electron microscopy, we found robust sex differences in axonal diameter (males>females) and g ratio (males>females). Removal of endogenous testosterone by castration was associated with lower axon diameter and lower g ratio in castrated (vs. intact) males. In vitro, Mibolerone influenced the axonal transport in a time- and dose-dependent manner, and increased the axon caliber as compared with vehicle-treated neurons. These findings are consistent with the role of testosterone in shaping the axon by regulating its radial growth, as predicted by the initial human studies.