Discordance in categorization of acute-on-chronic liver failure in the United Network for Organ Sharing database

•UNOS studies on ACLF are informing global transplant allocation policies, but the validity of these data is unknown.•We found that ACLF identified by UNOS is only weakly concordant with chart review.•Classification of acute decompensation and brain/respiratory failures are common sources of discordance.•These data highlight the importance of prospective studies regarding ACLF in LT and should encourage UNOS reform.