Opioids such as oxycodone and hydromorphone appear to be overprescribed in parts of B.C., resulting in higher rates of overdose deaths in those regions, according to a new study from the University of British Columbia.
The researchers also found that many of those who died from such an overdose did not fill a prescription for opioids in the year prior to their deaths, suggesting that some of the drugs are being diverted to the black market.
Steve Morgan, a professor in the university's School of Population and Public Health, said the findings underscore a need to change prescribing practices and better monitor the sale of opioids, a family of strong pain medications that also includes fentanyl and morphine.
While prescription opioid use has remained relatively stable in B.C. over the past decade, it has generally soared across the country. Between 2010 and 2014, the total number of opioid prescriptions dispensed in Canada climbed 24 per cent, reaching 21.7 million last year.
For the study, the researchers examined data from 2004 to 2013 on opioid prescriptions dispensed and prescription opioid-related deaths across B.C., finding a strong correlation between the two.
"We did indeed find that regions that had higher rates of prescription opioid purchases also had higher rates of prescription opioid-related deaths," Prof. Morgan said, adding that the rates of both were particularly high in parts of the southern Okanagan and Fraser Valley regions.
In those areas, there were, on average, more than 15 opioid-related deaths per 100,000 population, compared with fewer than five in most of Vancouver, with the exception of the Downtown Eastside. There was no correlation between the prescriptions and suicides, meaning the deaths were from accidental overdoses, Prof. Morgan said.
Nearly one-third of women and nearly two-thirds of men who died from prescription opioid overdoses had not filled a prescription for the drugs in the year prior, suggesting some legal opioids are being diverted to the illegal drug market.
The study did not include illicit opioids such as heroin.
Dr. Ailve McNestry, deputy registrar for the College of Physicians and Surgeons of B.C., said the higher prescription rates could be at least partially attributed to local demographics.
"Some areas are known to be retirement areas, so the populations there would be expected to be somewhat older than the population average, and older people are more prone to suffer from both chronic non-cancer pain as well as pains related to cancers and end-of-life conditions," she said.
However, Dr. McNestry said the college could not rule out individual physicians' prescribing patterns.
Prof. Morgan said B.C. has some of the best and most comprehensive data in this area that could be better used in a clinical setting to prevent prescription-opioid related deaths.
"We're cautiously optimistic that the ingredients are there; it will require investment in information systems, and making those data sets less cumbersome, more clinically relevant and easier to access by professionals," he said.
B.C. physicians working in a transient-care setting, such as walk-in and methadone clinics, are expected to use PharmaNet, a provincial system that records all prescriptions, to review patients' prescription history. The college is now considering expanding the requirement to all health-care clinics, Dr. McNestry said.
The Ministry of Health has also experimented with an electronic prescription system that would remove a patient's ability to alter a paper prescription. However, that initiative has not yet advanced past two small pilot projects.
"Most physicians who have electronic medical records would love to be able to electronically prescribe," Dr. McNestry said. "They appreciate how much safer it would be and it would also minimize any confusion about what a physician has written."