OC5.1 - ECE_2788 - Sex differences in clinical presentation, management and outcome in hospitalized patients with hyponatremia

This is the authors' abstract. We don't add key points for this paper.

Introduction Hyponatremia is the most common electrolyte disorder in hospitalized patients. Observational studies show a higher prevalence of hyponatremia in hospitalized female patients, but other sex-related differences in hyponatremia among hospitalized patients remain largely unknown. Aim To explore the impact of sex on the clinical presentation, management and outcomes of hyponatremia in hospitalized patients. Methods Predefined secondary analysis of a large European multi-center trial that randomized hospitalized patients with hyponatremia (plasma sodium <130 mmol/L) to targeted correction or standard of care, aiming to evaluate the effects on mortality and rehospitalization. Sodium trajectories were modelled using multivariable linear mixed models adjusted for age, sex and etiology with patient-specific random effects. The effect of sex on mortality and rehospitalization was analyzed with a multivariate cox proportional hazard model adjusting for age, hyponatremia etiology, treatment received, baseline plasma sodium, and Charlson Comorbidity Index. The difference in the likelihood of receiving treatment was assessed using the chi-square test. Subgroup analyses were performed for both the standard of care group and the targeted therapy group. Results 2173 patients (52.2% female, median age 73 years, median baseline plasma sodium of 127 mmol/L) were analyzed. Female patients more frequently had diuretic-induced hyponatremia (RR 1.51, 95%CI 1.13-2.03), and less often hypervolemic hyponatremia (RR 0.77, 95%CI 0.63-0.93). Female patients more often reported symptoms at baseline (RR 1.10, 95% CI 1.06-1.13) and were more likely to receive treatment when randomized to the standard of care group (RR 1.16, 95%CI 1.06-1.27). Additionally, female patients had a slightly lower plasma sodium over the entire trajectory of hospitalization (−0.4 mmol/L, P = .003). Female sex was independently associated with a lower 30-day mortality (HR 0.59, 95%CI 0.43-0.81) and 30-day rehospitalization (HR 0.76, 95%CI 0.60-0.68) rate. These sex differences persisted when adjusting for hyponatremia etiology. Conclusions While having lower plasma sodium levels and more frequently reporting symptoms, hospitalized female patients with hyponatremia had a lower hazard for 30-day mortality and rehospitalization. This raises the question of whether sex-specific mechanisms underlie differences in hyponatremia symptomatology and outcomes.