Severity of community acquired hypernatremia is an independent predictor of mortality

Abstract

Hypernatremia develops commonly in critically ill patients during hospitalization, and is associated with adverse outcomes. However, community acquired hypernatremia (CAH) has been rarely studied. We conducted a study in patients who presented to an urban referral hospital, and were admitted with CAH. We retrospectively analyzed patients admitted to an urban tertiary care hospital from January 1, 2012 to December 31, 2014. CAH is defined as more than 147 mEq/L at admission in patients not transferred from other hospitals. Severity of hypernatremia is categorized as mild (148-150 mEq/L), moderate (151-154 mEq/L) or severe (≥155 mEq/L). All data were extracted from electronic medical records and the major outcome is hospital mortality. During the study period, 79,998 patients were admitted to the hospital. Of them, 178 patients (0.2%) had hypernatremia at the time of admission. 121 (68.0%) had mild hypernatremia, 33 (18.5%) had moderate hypernatremia, and 24 (13.5%) had severe hypernatremia at admission. During the hospital stay, 91 (51.1%) developed mild hypernatremia, 31 (17.4%) developed moderate hypernatremia and 56 (31.5%) developed severe hypernatremia. Mean duration of hypernatremia was 2.3 ± 2.0 days. The length of hospital stay was 7 (interquartile range 3-23) days and hospital mortality was 24.3%. Multivariate analysis shows that a peak sodium level that qualified as moderate [OR = 11.50, 95% CI (2.67-49.42)] or severe hypernatremia [OR = 5.18, 95% CI (1.43-18.79)] is an independent risk factor for hospital mortality compared to mild hypernatremia. Admission from the emergency department (ED), oral intake restriction, mean arterial pressure (MAP) and respiratory rate (RR) at admission time are also independently associated with hospital mortality. Maximum sodium level in CAH is independently associated with hospital mortality.

Keywords: Hypernatremia; Mortality; Severity.