This is a multi-center, nested cohort study intended to investigate the prevalence, risk factors, and outcomes of complications in patients with acutely decompensated cirrhosis, especially focused on Cytomegalovirus (CMV) reactivation, bacterial infections, hepatic encephalopathy, and Hepatorenal syndrome. Patients diagnosed with acutely decompensated cirrhosis were enrolled. Upon enrollment, detailed baseline data were collected and samples were harvested. Complications were assessed during hospitalization. Post-discharge follow-up was conducted through telephonic interviews at Day 30 and Day 90.