Objectives Hyperchloraemia is associated with poor clinical outcomes in sepsis patients; however, this association is not well studied for hypochloraemia. We investigated the prevalence of chloride imbalance and the association between hypochloraemia and 28-day mortality in ED patients with septic shock.

Methods A retrospective analysis of data from 11 multicentre EDs in the Republic of Korea prospectively collected from October 2015 to April 2018 was performed. Initial chloride levels were categorised as hypochloraemia, normochloraemia and hyperchloraemia, according to sodium chloride difference adjusted criteria. The primary outcome was 28-day mortality. A multivariate logistic regression model adjusting for age, sex, comorbidities, acid-base state, sepsis-related organ failure assessment (SOFA) score, lactate and albumin level was used to test the association between the three chloride categories and 28-day mortality.

Results Among 2037 enrolled patients, 394 (19.3%), 1582 (77.7%) and 61 (3.0%) patients had hypochloraemia, normochloraemia and hyperchloraemia, respectively. The unadjusted 28-day mortality rate in patients with hypochloraemia was 27.4% (95% CI, 23.1% to 32.1%), which was higher than in patients with normochloraemia (19.7%; 95% CI, 17.8% to 21.8%). Hypochloraemia was associated with an increase in the risk of 28-day mortality (adjusted OR (aOR), 1.36, 95% CI, 1.00 to 1.83) after adjusting for confounders. However, hyperchloraemia was not associated with 28-day mortality (aOR 1.35, 95% CI, 0.82 to 2.24).

Conclusion Hypochloraemia was more frequently observed than hyperchloraemia in ED patients with septic shock and it was associated with 28-day mortality.