BackgroundHyponatremia is associated with negative prognosis in several conditions like Congestive heart failure and acute MI (Myocardial Infarction), but its impact on the outcomes in patients with pulmonary embolism (PE) is not well studied. We aimed to study the association of hyponatremia in patients hospitalized with PE.MethodsA retrospective cohort study was designed using data obtained from the 2016 to 2019 combined National Inpatient Sample (NIS) database. Adult patients admitted with PE were identified and stratified based on the presence of hyponatremia. Primary outcomes assessed were, mortality, length of stay (LOS), and Total Hospitalization Charges (THC). Secondary outcomes included a diagnosis of Acute Kidney Injury (AKI), Acute Respiratory Failure (ARF), sepsis, Acute Cerebrovascular accident (CVA), arrhythmias and acute MI. Multivariate linear and logistic regressions were used to adjust for confounders.ResultsThere was a total of 750,655 adult hospitalizations for PE and among them 41,595 (5.5%) had a secondary diagnosis of hyponatremia. Hyponatremia was associated with an increased odds of mortality, 6.31% vs 2.91% (AOR:1.77, p = 0.000, 95% CI: 1.61-1.92), increased LOS, 6.79 days vs 4.20 days (adjusted difference of 2.20 days, p = 0.000, 95% CI: 2.04-2.37), as well as an increase in THC, 75,458.95 USD vs 46,708.27 USD (adjusted difference of 24,341.37 USD, p < 0.001, 95% CI: 21,484.58-27,198.16). Similarly, the presence of hyponatremia was associated with increased odds of several secondary outcomes measured.ConclusionHyponatremia is associated with an increased odds of death and attendant increase in LOS and THC. The odds of several secondary adverse clinical outcomes were also increased.