The combined impact of hyponatremia and hematocrit on the risk for 90-day readmission and death in patients with heart failure: dilutional hyponatremia versus depletional hyponatremia.

BACKGROUND

Hyponatremia is common in hospitalized patients with heart failure (HF) and predicts a poor prognosis after discharge. In general, hyponatremia can be divided into two types: dilutional or depletional.

OBJECTIVE

Assess the impact of hyponatremia type on short-term outcomes.

DESIGN

Retrospective cohort SETTINGS: Single center in China PATIENTS AND METHODS: We sorted patients by hyponatremia into two types: dilutional hyponatremia (DiH, with hematocrit <35%) and depletional hyponatremia (DeH, with hematocrit ≥35%). The Kaplan-Meier method and Cox regression analysis were used to identify the impact of hyponatremia types on the risk for 90-day readmission and death.

MAIN OUTCOME MEASURES

90-day readmission and death combined.

SAMPLE SIZE

1770 patients.

RESULTS

Hyponatremia was present in 324/1770 patients with 182 cases classified as DiH versus 142 as DeH. Kaplan-Meier analyses showed a higher incidence of poor short-term outcomes in hyponatremia compared with normonatremia (log-rank <.001), and the risk was higher in DiH than DeH although the difference was not statistically significant (log-rank =.656). Multivariate Cox regression analyses showed that only DiH was independently associated with short-term outcomes (HR=1.34, 95%CI: 1.02-1.77, =.038), but not DeH (HR=1.32, 95%CI: 0.97-1.80, =.081). Analysis of the secondary endpoints showed that DiH increased the risk of readmission but not death (HR=1.36, =.035 for readmission; HR=1.13, =.831 for all-cause death).

CONCLUSIONS

Low hematocrit, rather than high hematocrit, with hyponatremia was associated with a risk of 90-day readmission in patients with HF.

LIMITATIONS

Single center, nonrandomized.

CONFLICT OF INTEREST

None.