Assessing the Prevalence of Nonmedical Prescription Opioid Use in the General Canadian Population: Methodological Issues and Questions

Objective: To assess the prevalence of nonmedical prescription opioid use (NMPOU) in the Canadian general adult population in the context of rising overall prescription opioid (PO) consumption and related problems in North America. Method: The prevalence of NMPOU was assessed as a multiitem construct in the Canadian Alcohol and Drug Use Monitoring Survey (CADUMS; n = 16 672), an ongoing cross-sectional monthly random digit dialing telephone survey representative of the general Canadian population, aged 15 years and older. CADUMS data were collected between April and December of 2008 with a response rate of 43.5%. Results: About 22% of CADUMS respondents reported PO use in the last year, while 0.5% reported NMPOU during the same time frame. PO use was significantly higher among women than among men, and highest in the group aged 25 to 54 years. NMPOU was similar among men and women, and highest in the group aged 15 to 24 years. Conclusions: CADUMS data indicate an extremely low rate of NMPOU, especially given the levels of overall PO use, other PO-use related problems, and NMPOU levels estimated in the general US population where NMPOU has been assessed to be 10 times higher than in Canada. NMPOU survey item construction and response rates appear to strongly influence and potentially compromise NMPOU survey data. Existing NMPOU data and survey methods need to be validated for this important indicator in Canada, where increasing PO use and problem levels have been recognized as a significant and rising public health problem.