Photo: The Canadian Press

Researchers say opioid users in Vancouver's Downtown Eastside are increasingly testing positive for the potent painkiller fentanyl, which was linked to the majority of fatal overdoses in British Columbia last year.

Dr. William Honer, head of the University of British Columbia's psychiatry department, was part of a study that followed 237 people living in marginalized housing in the neighbourhood between March and July last year.

At the beginning of the study, he says urine samples from 45 per cent of people who reported using opioids tested positive for fentanyl, but five months later that number jumped to 100 per cent.

The BC Coroners Service released statistics Wednesday showing fentanyl was linked to 81 per cent of the 1,422 fatal overdoses across the province last year.

Honer's research included 103 people who were in opioid-replacement programs, where they were prescribed methadone, suboxone or prescription heroin.

He says over the five months of the study, half of those involved in the replacement programs submitted urine samples that tested positive for fentanyl.

He says the results show there is a need for more comprehensive treatment that addresses mental illness and physical ailments as well as addiction.