The acetaminophen (paracetamol) overdose rate in Calgary, Canada dropped by over 40% in the decade to 2004, without a change to the smaller pack sizes that were credited with overdose reductions in the UK.
The results published in the online open access journal BMC Public Health suggest that young women, Aboriginals and those on social security remain at greatest risk.
A University of Calgary, Canada team led by Dr. Robert Myers used administrative data to review over 1500 patients hospitalised for acetaminophen overdose between 1995 and 2004. Since 1995, the hospitalisation rate has dropped 41% from 19.6 per 100 000 population to 12.1 per 100 000 in 2004. Myers team found that although for under 50s the rate fell 46%, there was a 50% jump in hospitalisations for the over 50s. Female overdosing fell to a greater extent than it did for males (46% vs. 29%).
The majority of overdoses were intentional (85%), with the remainder made up of 13% accidental cases and 2% homicides or of unclear intent. Accidental overdoses fell between 1995 and 2002, but then began to rise again. Over 100 products are available over the counter, sometimes containing relatively large amounts of acetaminophen. The authors suggest that lack of patient and physician awareness may account for at least part of the increase in accidental overdoses.
In 1998 UK legislation limited packets of acetaminophen to 16 x 500mg tablets. The authors note the overdose rate in Calgary is about one fifth that reported in the UK, despite similar suicide rates. UK acetaminophen overdose cuts have largely been attributed to the package size restrictions, however no such restrictions have been imposed in Canada. Acetaminophen (paracetamol) overdose is the most common cause of acute liver failure, accounting for as many as 50% of acute liver failure cases.