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  • Researchers mapped out a snapshot of opioid use disorder in British Columbia
  • Out of 55,000 people with opioid use disorder, 71% received substitution therapy
  • However, only 16% continued to receive care for opioid use disorder after one year

A “cascade of care” type of analysis has been applied to several health conditions to see at which steps in the continuum of diagnosis to treatment (and in some cases cure) patients are either falling out or stalling in their progression to better health. These analyses can reveal potential barriers to the flow of patients through the system. Stages in the continuum of care where potential barriers are identified can then receive additional attention and interventions designed to help patients move to the next stage of care. Cascade of care analyses have been successfully used to understand barriers to better health in people with HIV, hepatitis C virus (HCV) infection and diabetes.

Now scientists in British Columbia are using the cascade of care framework to examine issues in the diagnosis and treatment of opioid use disorder (OUD). This is important because analysis has found that in the past several years a majority of opioid-related deaths in Canada and the United States have been related to inadvertent exposure to fentanyl or related chemical compounds. Helping people with OUD can provide a pathway to assistance into harm reduction initiatives (including sterile needles, syringes and other substance use equipment; support from peers; supervised injection sites) and, when appropriate, entry into opioid substitution therapy (OST). These efforts can help save lives and reduce the risk of people with OUD getting blood-borne germs such as HIV and hepatitis C virus.

Focus on opioid use disorder

Opioid use disorder is a term that merges and replaces older diagnostic categories—such as “abuse” and “dependence”—related to substance use. According to a team of scientists from Canada, Australia, England and the U.S. who study and help people with problematic substance use, “the likelihood of OUD following opioid use is high compared with other drugs. Some individuals are highly vulnerable to OUD following opioid use, whereas others do not develop OUD….”

Although there are different ways of categorizing OUD, the international team stated: “The critical factors in OUD are that people persist in using opioids despite incurring extra physical, mental, social or [other] problems as a result of their opioid use, that tolerance to the effects of opioids develops, and that there is a switch and preoccupation with minimizing the effects of withdrawal over achieving euphoria.”

The scientists further stated: “OUD is best understood as a biopsychosocial disorder in which genetic factors, adverse early dependence, mental illness, social norms, drug exposure and market availability can influence the extent of exposure and the opportunity for drug use, as well as the progression and development of OUD and associated harms.”

The scientists viewed OUD in the following way:

“As a chronic and often relapsing disorder; thus medical and psychological therapy should be delivered within a framework similar to that used for the treatment of other disorders. OUD requires long-term care that is adjusted to meet the needs of individual patients…. The aim of treatment should be to stabilize the physiological and psychological disruption caused by chronic opioid exposure, which, in turn, enables reduced opioid use and the many associated physical and social harms. In this manner, patients can enter remission, providing an opportunity to address other psychological and medical issues related to drug use.”

The OUD cascade of care

A team of scientists from the B.C. Centre for Excellence in HIV/AIDS, the BC Centre on Substance Use, local universities and the BC Ministry of Mental Health and Addictions collaborated on research to better understand the OUD cascade of care in that province. The team reviewed and analysed data collected over a period of 20 years. They found that there were about 55,000 people who injected street drugs and who had a diagnosis of OUD. A large proportion of people in this group (71%) received opioid substitution therapy (OST)—including methadone, buprenorphine, naloxone or slow-release morphine—at some point during the study. However, only 16% of people with OUD remained in care for at least one year.

The study shows that much remains to be done in B.C. to connect people who use drugs to addiction medicine services and harm reduction organizations and to help such people continue to use these services so they can reduce the risk of overdose and other issues that affect their health.

Study details

The scientists accessed the following provincial databases to find out about healthcare used by people with OUD:

  • PharmaNet – this provides information about prescriptions for OUD treatment
  • Discharge Abstract Database – this has information on why people were hospitalized
  • Medical Services Plan – this has information about physician billing records and can reveal reasons doctors provided care
  • B.C. Vital Statistics – this contains information on deaths and causes of deaths

In general, data were collected from January 1996 to December 2017.


The scientists found that there were about 77,000 people diagnosed with OUD during the course of the study. Of these people, 55,470 were alive by the end of the study.

Trends in diagnoses

According to the scientists, “the number of people with OUD increased substantially from 15,972 in 2001 to 55,470 in 2017, reflecting a greater than three-fold increase in 16 years.”

Trends in care

The scientists stated: “As of 2017, although 71% of diagnosed people with OUD had ever been engaged in [OST], 33% were currently on [OST], and only 16% had been retained in care for one year.”

New diagnoses of OUD

For the analysis of new diagnoses, which were made in a community-based clinic or hospital, scientists focused on the period from 2012 to 2015 and found the following:

  • 32% of people were aged 25 to 34 years
  • 95% of new diagnoses were in people living in urban areas
  • most people (61%) were male
  • 44% of participants who were seen in a community-based clinic received OST within three months of being diagnosed with OUD. In contrast, among participants who were initially seen in a hospital, only 7% received OST within three months of their diagnosis.

Rural vs. urban

As mentioned earlier, the vast majority of people (96%) lived in an urban area. In general, people with OUD who lived in a rural area were less likely to receive care for OUD, and when they did, they were less likely to stay in care.

A snapshot in time

The scientists were able to find out some information about people who were not receiving treatment for OUD as of March 31, 2016. Here is the distribution of this population:

  • never used OST – 14,991 people
  • had used OST in the past but were not currently taking OST – 26,589

The scientists stated: “Regardless of the time since diagnosis or discontinuation [of OST], a large majority of clients not engaged in [OST] were receiving at least routine outpatient care in the previous 12 months….” They added that “hospitalizations were common,” particularly among people who discontinued OST within the past year.

Bear in mind

The present study is a good first step in trying to understand points in the healthcare system where people with OUD do not enter or fall out of care.

The scientists made the following points and recommended the following courses of action:

  • “Future efforts should focus on the engagement of individuals who are accessing care for OUD-related causes but not receiving [OST].”
  • “Since a majority of the population was living with mental health conditions, chronic pain and other substance use disorders prior to OUD diagnosis, targeted interventions for OUD identification and treatment engagement should focus in settings providing care for these conditions. Additionally, settings managing infectious diseases provide opportunities to engage people with OUD in treatment as OUD often comes with risk of HCV and HIV infection among those who inject drugs.”
  • “Hospitalizations were common among those recently diagnosed [with OUD] or disengaged from [OST]. Inpatient care settings, particularly the Emergency Department (ED) present promising solutions in OUD screening and [OST] initiation. Many North American EDs have initiated buprenorphine for patients with referral to outpatient care with reported success in retention and reduction of ED visits. Similarly, a BC pilot project is currently underway to provide ED opioid overdose patients with take-home buprenorphine-naloxone upon discharge.”

To improve access to opioid substitution therapy in rural areas, the scientists suggested a number of strategies, including the following:

  • stigma reduction programs
  • increasing the number of pharmacies that can dispense OST
  • increasing reimbursement rates for OST prescription and dispensation
  • providing telehealth and telementoring initiatives

The B.C. scientists noted that, according to their data, “fewer than 3% of people with OUD achieve long-term remission and those left untreated are likely to fall victim to an overdose, further emphasizing the importance of adoption of a chronic disease model for OUD and its recognition as treatable chronic disease, with a range of treatment options and no imposed time restrictions.” To increase sustained engagement in care for OUD, the B.C. scientists recommended the following steps:

  • increased access to alternative forms of OST
  • more care for populations experiencing OUD
  • quality improvement initiatives
  • peer-to-peer support

Meeting the needs of people with OUD

According to the B.C. scientists, “for many people with OUD, [OST] is not an immediate goal. Many people with OUD have a desire to [reduce or quit substance use], while some feel stigmatized for using [OST] and are not inclined towards treatment. The availability of harm reduction services such as overdose prevention facilities, supervised consumption sites, naloxone kit distribution, drug checking services, outreach and peer to peer support programs have all been priority interventions for people with OUD choosing not to engage in treatment and represent opportunities to intervene and refer individuals to treatment and social support services as needed and appropriate.”


The B.C. scientists noted that the “identification and prevention of OUD are also key components of a comprehensive approach to OUD. Screening for OUD in all relevant health care settings as well as increasing physician and nurse training in OUD identification and treatment are instrumental to support care integration.”


British Columbia Centre for Excellence in HIV/AIDS

British Columbia Centre on Substance Use

Opioid agonist therapy: Does it have a role to play in helping to prevent hepatitis C and HIV?Prevention in Focus

Responding to an Opioid and Stimulant Overdose

Overdose Prevention Site at St. Paul’s HospitalProgramming Connection

keepSIX Supervised Consumption ServiceProgramming connection

Trends in deaths among people with hepatitis C virus in British ColumbiaCATIE News

Prescribed opioids associated with increased risk of pneumoniaCATIE News

Patterns of substance use associated with fentanyl exposure in VancouverCATIE News

Rapid rise in fentanyl exposure among some substance users in VancouverCATIE News

Sean R. Hosein


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