Frequency and Outcomes of Acute‐on‐Chronic Liver Failure in Nonelective Cirrhotic Patients Admitted to a Brazilian ICU: A Single‐Center Retrospective Study

<b>Introduction:</b> Acute-on-chronic liver failure (ACLF) is a severe complication of cirrhosis characterized by acute decompensation (AD), organ failure(s), and high mortality. <b>Aims:</b> To investigate the frequency and the clinical course of ACLF in intensive care unit (ICU) patients at different time points, using CLIF-C and NACSELD criteria as well as to assess their influence on mortality. <b>Methods:</b> Patients admitted with AD with and without ACLF were retrospectively evaluated. <b>Results:</b> 595 patients (443 males, mean age: 66.6 ± 12.0 years) were admitted due to AD (<i>n</i> = 381) or ACLF (<i>n</i> = 214). According to the CLIF-C criteria, 119 patients (20%) had ACLF Grade I, 63 (10.6%) had ACLF Grade II, and 32 (5.4%) had ACLF Grade III at admission. Using the NACSELD, 155 patients (26.1%) had ACLF at admission. Infection was the main factor associated with ACLF at admission (<i>n</i> = 57; 27%, <i>p</i> = 0.001). In total, 104 (17.5%) patients died during hospitalization. ACLF grade at admission (OR: 4.6; 95% CI: 2.45-8.67; NS: 0.0001), use of vasopressors (OR: 3.83; 95% CI: 1.15-12.7; NS: 0.02), and CLIF-C ACLF (OR: 1.12; 95% CI: 1.06-1.19; NS: 0.0001) were independently associated with in-hospital mortality. The improvement in organ dysfunction after 7 days of intensive care was associated with a reduction in the risk of in-hospital mortality compared to the 3-day period (OR: 0.098; 95% CI: 0.047-0.204 vs. 0.253; 95% CI: 0.127-0.504; <i>p</i> < 0.00001, respectively). <b>Conclusion:</b> ACLF is associated with significant mortality in ICU patients, the CLIF-C criteria appear to be more effective for prognostic assessment than NACSELD, and 7 days of intensive care may improve clinical outcomes.