High levels of opioid analgesic co-prescription among methadone maintenance treatment clients in British Columbia, Canada: results from a population-level retrospective cohort study.

Background And Objectives: The non-medical use of prescription opioids (PO) has increased dramatically in North America. Special consideration for PO prescription is required for individuals in methadone maintenance treatment (MMT). Our objective is to describe the prevalence and correlates of PO use among British Columbia (BC) MMT clients from 1996 to 2007.