Is chronic poisoning with acetaminophen in children a frequent occurrence in Toronto?

BACKGROUND: Acetaminophen is a common cause of poisoning in children. Recent American studies suggest that acetaminophen poisonings pose serious risks in children, particularly in the case of chronic poisoning caused by therapeutic error. OBJECTIVE: To evaluate whether chronic acetaminophen poisoning in children is a frequent occurrence in a large, Canadian, urban population. PATIENTS AND METHODS: Retrospective study. Charts of all patients admitted to The Hospital for Sick Children, Toronto, Ontario from January 1, 1990 to June 31, 1996 with an acetaminophen overdose were reviewed. RESULTS: A total of 110 patients were admitted within the study period; only four of whom were preschool children (younger than five years of age). Among the preschool children, three had an acute overdose and one had possible chronic poisoning by therapeutic error. All preschool children were treated with N-acetylcysteine; one developed hepatotoxicity (aspartate aminotransferase or alanine aminotransferase greater than 1000 U/L) after presenting 24 h after acute ingestion. Of the remaining patients, all were adolescents; 102 had acute intentional overdose and four had staggered intentional overdoses. Fifty-three adolescents were treated with N-acetyl cysteine. Hepatotoxicity was present in 13 of 63 adolescents (21%). No patients required liver transplantation or died. CONCLUSIONS: Contrary to American experience, chronic acetaminophen poisoning, including therapeutic error in children in Toronto, is a rare occurrence - most cases of acetaminophen poisonings are acute intentional ingestion in adolescents.