Combined effects of hyponatremia and hepatic encephalopathy on inpatient mortality

Although hyponatremia and hepatic encephalopathy (HE) are known independent predictors of mortality, their combined effect is unknown. We investigated whether the inpatient mortality differed among patients with both hyponatremia and HE compared to those with either hyponatremia or HE alone. In this retrospective study, data were extracted from the National Inpatient Sample (NIS) to identify US adults (aged ≥18 years) with cirrhosis between January 1st, 2016, and December 31st, 2017. We analyzed the effects of hyponatremia, HE, or a combination of hyponatremia and HE on inpatient mortality using logistic regression. Among 309,841 cirrhosis-related admissions, 22,870 (7%) patients died during hospitalization. Those with a combination of hyponatremia and HE had higher mortality (14%) than those with HE only (11%), hyponatremia only (9%), and neither hyponatremia nor HE (6%) (p<0.001). When compared to patients without hyponatremia or HE, patients with both hyponatremia and HE had the highest odds (adjusted odds ratio or aOR) of inpatient mortality (aOR 1.90, 95% CI: 1.79 – 2.01) followed by patients with HE only (aOR 1.75, 95% CI: 1.69 – 1.82) and patients with hyponatremia only (aOR 1.17, 95% CI: 1.12 – 1.22). Patients with HE only had 50% higher odds of inpatient mortality when compared to those with hyponatremia only (aOR: 1.50, 95% CI: 1.43 – 1.57). In this nationwide study, the presence of both hyponatremia and HE was associated with higher inpatient mortality than either hyponatremia or HE alone.