Risk Factors for Acetaminophen-induced Liver Injury: A Single-center Study from Japan.

Purpose: Acetaminophen has been increasingly used for the treatment of cancer-related pain in Japan since the revision of the package insert on January 21, 2011. However, high-dose acetaminophen may cause liver injury. The objectives of this study were to investigate the prevalence of liver injury in patients receiving acetaminophen and to identify the risk factors.

Methods: The subjects were patients who were treated with acetaminophen ≥1500 mg/d for ≥4 weeks at Ehime University Hospital between April 2011 and December 2014. Drug-induced liver injury was evaluated by alanine aminotransferase and alkaline phosphatase levels, Naranjo score, and Child-Pugh classification.

Findings: A total of 287 of 562 patients were treated for 4 weeks with acetaminophen ≥1500 mg/d. Twenty of 102 patients analyzed had drug-induced liver injury. Multivariate analysis was performed with variables from the results of univariate analysis (sex, age ≥70 years, abnormal alanine aminotransferase and alkaline phosphatase levels, and serious liver disease), and age ≥70 years and serious liver disease were significant risk factors.

Implications: The findings from the present observational, single-center study suggest that serious liver disease before administration is an independent risk factor for acetaminophen-induced liver injury.