Opioid addiction is a growing concern for many countries, especially among women living in Canada and the U.S. But in Canada specifically, a new study finds current treatment protocols don't take into account the sex differences associated with drug addiction.

"With the rising number of women seeking treatment for opioid-related problems, there is growing need for a reevaluation of sex and gender differences in opioid dependence and treatment," researchers wrote. "Methadone maintenance treatment (MMT) is the most common form of opioid agonist therapy. … However, most of what we currently know about methadone treatment is based primarily on studies that included few or no women at all. Existing treatment options remain targeted toward opioid users of the past; primarily young, inner-city, heroin-injecting men."

Researchers added identifying sex- and gender-specific patterns of drug addiction — in this case prescription painkillers, like OxyContin and codeine — is necessary to informing effective standards of care and clinical practice. In which case, researchers set out to provide an update of opioid users in methadone treatment in Ontario, Canada, as well as "evaluate sex differences in substance use, health status, and social functioning among men and women receiving treatment."

For the study, 503 men and women with opioid dependence disorders agreed to participate; each participant was receiving treatment under the Canadian Addiction Treatment Centres (CATC) organization. After they were recruited, researchers asked participants to provide information on their respective demographics, treatment characteristics, age of initial opioid use, and psychiatric history. They also used tools to measure functioning across several "life domains related to addiction," including substance use, physical and psychological health, and health risk behavior.

In the end, researchers spoke with men and women receiving treatment from 13 CATC clinics, and when compared to men, women were more likely to have physical and psychological health problems (think chronic pain and hepatitis C), and childcare responsibilities. They were also more likely to have a family history of psychiatric illness. Men, on the other hand, were more likely than women to be employed and more likely to smoke cigarettes; both men and women frequently smoked marijuana.

"Women, who are close to half of the opioid user population, experience a higher burden of disease related to opioid disorders, with respect to physical and psychological disorders and related symptoms," researchers said. "Women are more likely to have initiatiated their substance dependence through prescription opioids, presumably because of their higher rates of chronic pain." The latter may be a result of women's "heightened pain perception and sensitivity."

Ultimately, these findings highlight how opioid dependency has changed in recent years. Compared to the 1990s, the average patient is now older. Injection drug use has also dropped by 60 percent, which may account for the 50 percent reduction in rates of HIV, researchers said.

Researchers said their findings reveal new, important patterns among men and women addicted to drugs, and "can be used to advance our understanding of addiction and promote strategies for effective treatment and management of opioid use disorder among men and women."

But for women especially, emphasizing the need for fundamental services, from childcare to medical assistance, could significantly improve how they are specifically treated and taught to manage their opioid use disorder.

Source: Samaan Z, et al. Sex differences in substance use, health, and social functioning among opioid users receiving methadone treatment: a multicenter cohort study. Biology of Sex Differences. 2015.