Hyperchloraemia is associated with acute kidney injury and mortality in the critically ill: A retrospective observational study in a multidisciplinary intensive care unit.

PURPOSE: The aim of this study was to determine whether serum chloride and changes in serum chloride over time were associated with acute kidney injury (AKI) or intensive care unit (ICU) mortality in a heterogenous critically ill population.

MATERIALS AND METHODS: The study was a retrospective observational study of 250 adult patients admitted to a multidisciplinary academic ICU. Serum chloride within 48 h of admission, changes in chloride, and other biochemical and clinical parameters were evaluated as predictors of AKI and mortality.

RESULTS: Hyperchloraemia occurred in 143 (57.2%) patients within 48 h of ICU admission. Hyperchloraemia at 48 h was significantly associated with AKI, OR = 6.44 (95% CI 2.95-14.10) and mortality, OR = 2.46 (95% CI 1.22-4.94) on univariate analysis, with this association persisting on multivariable analysis. An increase in serum chloride was also associated with a significantly increased risk of AKI and mortality on univariate analysis. Hyperchloraemia on admission was, however, not associated with AKI or death. Of the 150 patients with AKI, 147 (98.0%) had developed AKI by 48 h.

CONCLUSIONS: Hyperchloraemia and increasing serum chloride are associated with adverse outcomes in critically ill patients. There is equipoise as to whether this represents an association, an epiphenomenon or causation.