Impact of liver disease, alcohol abuse, and unintentional ingestions on the outcomes of acetaminophen overdose

Background & Aims: Acetaminophen overdose is the most common cause of acute liver failure in the U.S. and other Western countries. Unintentional overdoses, alcohol abuse, and underlying liver disease might increase the risk of hepatotoxicity. In this population-based study, we examined outcomes of acetaminophen overdose, with particular attention to these risk factors. Methods: Patients hospitalized for acetaminophen overdose between 1995 and 2004 were identified retrospectively by using administrative data. Comorbid conditions, suicidal intent, and hepatotoxicity were identified by using International Classification of Diseases-Ninth Revision-Clinical Modification and International Statistical Classification of Diseases and Health-Related Problems, 10th revision diagnostic codes. Results: During the 10-year interval, 1543 patients were hospitalized for acetaminophen overdose; 34% were alcohol abusers, 3% had liver disease, and 13% overdosed unintentionally. Seventy patients (4.5%) developed hepatotoxicity. Unintentional overdoses (odds ratio [OR], 5.18; 95% confidence interval [CI], 3.00 - 8.95), alcohol abuse (OR, 2.21; 95% CI, 1.30-3.76), underlying liver disease (OR, 3.50; 95% CI, 1.57-7.77), and N-acetylcysteine treatment (OR, 6.75; 95% CI, 2.78-16.39) were independently associated with hepatotoxicity. Fifteen patients (1.0%) died in-hospital; risk factors included older age, unintentional overdoses, alcohol abuse, comorbidities including liver disease, and hepatotoxicity (14% vs 0.3%; P <.0005). During a median follow-up of 5.2 years (range, 1 day-11.0 years), 79 patients (5.1%) died. Approximately half of these deaths were due to preventable conditions including suicide, substance abuse, and trauma. Conclusions: In this population-based study, acetaminophen overdose had a relatively benign short-term course but was associated with substantial long-term mortality caused by preventable conditions. Acetaminophen-related hepatotoxicity is more common in patients with unintentional overdoses, alcohol abuse, and underlying liver disease.