Model with serial ammonia measured on ICU days 1 and 3 predicted hospital mortality with reasonably good discrimination
By Elana Gotkine HealthDay Reporter
THURSDAY, Aug. 3, 2023 (HealthDay News) — For patients with cirrhosis in the intensive care unit (ICU), there is an association between early serum ammonia and hospital mortality, according to a study published online July 20 in Alimentary Pharmacology and Therapeutics.
Filipe S. Cardoso, M.D., from Nova Medical School in Lisbon, Portugal, and colleagues assessed the impact of serum ammonia variation on outcomes in critically ill patients (aged 18 years and older) with cirrhosis. The derivation cohort included 492 patients, and the validation cohort included 600 patients.
The researchers found that median ammonia was higher for patients with grade 3/4 hepatic encephalopathy (HE) than those with grade 2 or grade 0/1 HE (112 µmol/L versus 88 and 77 µmol/L, respectively) on ICU day 1. Furthermore, compared with survivors, hospital nonsurvivors had higher medium ammonia (99 versus 86 µmol/L). Higher day 2 ammonia was independently associated with higher hospital mortality (adjusted odds ratio per 10 µmol/L increment, 1.11) after adjustment for significant confounding variables (age, HE, vasopressor use, and renal replacement therapy delivery). A model with serial ammonia (ICU days 1 and 3) predicted hospital mortality with reasonably good discrimination (C-statistic, 0.73) and calibration (R2, 0.19) in the validation model.
“We believe our study adds to the current literature by further supporting the potential clinical utility of serial serum ammonia measurements in the ICU,” the authors write. “In fact, serial serum ammonia measurements may help to follow patients’ clinical trajectories and improve prognostic evaluations in this setting.”
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