Hypochloremia as a novel adverse prognostic factor in acute liver failure

Background and Aims Emerging evidence has identified hypochloremia as an independent predictor for mortality in multiple conditions including cirrhosis. Acute liver failure (ALF) is frequently complicated by electrolyte abnormalities. We investigated the prognostic value of hypochloremia in a large cohort of ALF patients from North America. Methods The Acute Liver Failure Study Group (ALFSG) registry is a longitudinal cohort study involving 2588 ALF patients enrolled prospectively from 32 North American academic centres. The primary outcome was a composite of 21-day all-cause mortality or requirement for liver transplantation (death/LT). Results Patients with hypochloremia (<98 mEq/L) had a significantly higher 21-day mortality rate (42.1%) compared with those with normal (27.5%) or high (>107 mEq/L) chloride (28.0%) (p < .001). There was lower transplant-free cumulative survival in the hypochloremic group than in the normo- or hyper-chloremic groups (log-rank, chi(2) 24.2, p < .001). Serum chloride was inversely associated with the hazard of 21-day death/LT with multivariable adjustment for known prognostic factors (adjusted hazard ratio [aHR]: 0.977; 95% CI: 0.969-0.985; p < .001). Adding chloride to the ALFSG Prognostic Index more accurately predicted risk of death/LT in 19% of patients (net reclassification improvement [NRI] = 0.19, 95% CI: 0.13-0.25) but underestimated the probability of transplant-free survival in 34% of patients (NRI = -0.34, 95% CI: -0.39 to -0.28). Conclusions Hypochloremia is a novel independent adverse prognostic factor in ALF. A new ALFSG-Cl Prognostic Index may improve the sensitivity to identify patients at risk for death without LT.