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Opioid addiction originates from prescription painkillers for more than half of female methadone clinic patients

Painkillers prescribed by doctors are the starting point for addiction to opioids for more people than heroin. This is according to a new study of 503 patients attending methadone clinics, published in the open access journal Biology of Sex Differences. The study highlights the differences in profile of those who currently seek treatment and people that treatment plans were originally designed for.

The results show that over half (52%) of women and over a third (38%) of men reported doctor-prescribed painkillers as being their first contact with opioid drugs, a family of drugs which include prescription medicines such as oxycontin and codeine, as well as illicit drugs such as heroin.
Researchers from McMaster University in Canada recruited men and women from 13 methadone clinics in Ontario, Canada. The participants were attending the clinics for opioid dependence disorder, and provided researchers with detailed information on their health and lifestyle, as well as urine tests for drug use.

The aim of the study was to identify any significant gender differences between the men and women attending the clinics. Compared to men, women were found to have more physical and psychological health problems, more childcare responsibilities, and were more likely to have a family history of psychiatric illness.

Men were more likely than women to be in employment, and were more likely to smoke cigarettes. Men were also more likely to report having smoked cannabis, although rates of cannabis use were relatively high among both men and women, with nearly half (47%) of participants overall self-reporting use of the drug in the month prior to the study.

Lead author, Monica Bawor, from McMaster University, said: “Most of what we currently know about methadone treatment is based on studies that included few or no women at all. Our results show that men and women who are addicted to opioids have very different demographics and health needs, and we need to better reflect this in the treatment options that are available. 

“A rising number of women are seeking treatment for opioid addiction in Canada and other countries yet, in many cases, treatment is still geared towards a patient profile that is decades out of date – predominantly young, male injecting heroin, and with few family or employment responsibilities.”

The study highlights the changing profile in recent decades of people addicted to opioids. Compared to results from studies in the 1990s, the average age of patients being treated for opioid addiction is older (38 vs. 25 years), with patients starting opioid use at a later age (25 vs. 21 years). Injecting drug use has reduced by 60%, and there has been a 50% reduction in rates of HIV in opioid users as a result. 

At the same time, there has been a 30% increase in the number of patients becoming addicted to opioids through doctor-prescribed painkillers, usually for chronic pain management. In Canada, the number of opioid painkiller prescriptions has doubled in the last two decades, and according to the WHO, Canada consumes more opioid painkillers than any other country.

Monica Bawor said: “It’s not clear why women are disproportionately affected by opioid dependence originating from prescription painkillers – it could be because they’re prescribed painkillers more often due to a lower pain threshold, or it might simply be because they’re more likely than men to seek medical care. Whatever the reasons, it’s clear that this is a growing problem in Canada and in other countries, such as the US, and addiction treatment programmes need to adapt to the changing profile of opioid addiction.”


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Notes to editor:

1. Research article

Sex differences in substance use, health, and social functioning among opioid users receiving methadone treatment: a multicentre cohort study
Monica Bawor, Brittany B. Dennis, Michael Varenbut, Jeff Daiter, David C. Marsh, Carolyn Plater, Andrew Worster, Meir Steiner, Rebecca Anglin, Guillaume Pare, Dipika Desai, Lehana Thabane and Zainab Samaan
Biology of Sex Differences 2015

Article available at journal website.

Please name the journal in any story you write. If you are writing for the web, please link to the article. All articles are available free of charge, according to BioMed Central's open access policy.

2. Biology of Sex Differences considers manuscripts on all aspects of the effects of sex on biology and disease.

Sex has profound effects on physiology and the susceptibility to disease. The function of cells and organs depends on their sex, determined by the interplay among the genome and biological and social environments. The study of sex differences is a discipline in itself, with its own concepts and methods that apply across tissues. 

3. BioMed Central is an STM (Science, Technology and Medicine) publisher which has pioneered the open access publishing model. All peer-reviewed research articles published by BioMed Central are made immediately and freely accessible online, and are licensed to allow redistribution and reuse. BioMed Central is part of Springer Science+Business Media, a leading global publisher in the STM sector.