Hypernatremia at Hospital Discharge and Out of Hospital Mortality Following Primary Intracerebral Hemorrhage.

Abstract

In patients with intracerebral hemorrhage (ICH), it is not clear if hypernatremia is merely a marker of disease severity or if elevated sodium levels are harmful. We hypothesized that hypernatremia at hospital discharge in primary ICH patients would be associated with increased mortality following discharge. We performed a two-center observational study of critically ill ICH patients in Boston. We studied 5100 patients, age ≥18years, who were diagnosed with ICH (ICD-9 code 431), received medical or surgical critical care between 1997 and 2011 and survived hospitalization. The exposure of interest was serum sodium within 24h of hospital discharge, categorized as Na≤145mmol/L and Na>145mmol/L. The primary outcome was 30-day post-discharge mortality. Odds ratios were estimated by logistic regression models adjusted for age, race, gender, Deyo-Charlson Index, patient type (medical versus surgical) and sepsis. In ICH patients who received critical care and survived hospitalization, the serum sodium at discharge was a predictor of post-discharge mortality. Patients with a discharge Na>145mmol/L have an OR for mortality in the 30days following hospital discharge of 1.82 (95%CI 1.38-2.38; P<0.001) and an adjusted OR of 1.87 (95%CI 1.40-2.48; P<0.001) both relative to patients with a discharge Na≤145mmol/L. The adjusted model showed good discrimination AUC 0.77 (95%CI 0.74-0.79) and calibration (Hosmer-Lemeshow χ (2) P=0.68). In critically ill ICH patients who survive hospitalization, hypernatremia at the time of discharge is a robust predictor of post-discharge mortality.