The rate of codeine-related deaths in Australia more than doubled between 2000 and 2009, driven primarily by an increase in accidental overdoses, according to research published in the Medical Journal of Australia.
Ms Amanda Roxburgh and colleagues from the National Drug and Alcohol Research Centre at the University of New South Wales in Sydney, using data from the National Coronial Information System, found that codeine-related deaths had increased from 3.5 to 8.7 per million population between 2000 and 2009. The number of deaths due to accidental codeine overdose also increased significantly, with a 9.3% rise recorded each year, from 1.8 to 5.1 deaths per million persons.
Of the 1437 deaths included in the study, just under half (48.8%) were attributed to accidental overdose, and a third (34.7%) to intentional self-harm.
"More than half (53.6%) of the cases of codeine-related death included a history of mental health problems, 36.1% a history of substance use problems (including misuse and dependence), 35.8% a history of chronic pain, 16.3% a history of injecting drug use, and 2.7% a history of cancer", the researchers wrote.
"Deaths attributed to heroin, Schedule 8 opioids, and multiple opioid toxicity were more common than codeine-related deaths.
"The rate was highest for heroin- and Schedule 8 opioid-related deaths, at about 16 deaths per million persons for each in 2009.
"Most codeine-related deaths (1201 = 83.7%) during 2000-2013 were attributed to multiple drug toxicity. A small proportion (113 = 7.8%) were specifically attributed to codeine toxicity. ... The remaining 123 deaths (8.5%) were attributed to other underlying causes, such as coronary heart disease, cardiovascular conditions, or other drug toxicity."
More codeine is consumed in the United Kingdom, Canada and Australia than any other opioid. Codeine is also one of the most accessible opioids, available without prescription (over-the- counter) in the UK, Canada, France, New Zealand and Australia.
The risks of prolonged codeine use include tolerance, which may lead to escalating doses and dependence; gastrointestinal disease and renal failure when used in combination with ibuprofen over long periods; and hepatotoxicity when combined with paracetamol over long periods.
"Those who had intentionally overdosed were more likely to be older, female and have a history of mental health problems; those who had accidentally overdosed were more likely to have a history of substance use problems, chronic pain and injecting drug use", the researchers found.
"These patterns suggest that in the accidental deaths there may be evidence of: (a) codeine being used to top up prescribed pain medication; (b) dose escalation of codeine; and (c) the development of codeine dependence.
"These characteristics highlight a complex patient population in need of specialist services."
The authors wrote that they believed their results suggested the need for "different public health and clinical strategies to prevent fatal intentional and accidental codeine overdoses".
Suicide prevention strategies to reduce intentional overdoses; an increased focus on screening for depression and suicide risk at the primary care, prescribing level; and an increased role for pharmacists in the education of consumers purchasing codeine products over the counter were suggested for mitigation of overdoses.
"Patient education is also essential", the researchers wrote.
"It is clearly necessary to increase the capacity to identify high-risk patients in primary care and to respond more effectively to their needs. Increasing the capacity of specialist pain, addiction and mental health treatment services in Australia should also be a priority."