McMaster University

Michael G. DeGroote
National Pain Centre

Scope of Search

Canadian Guideline for Safe and Effective Use of Opioids for Chronic Non-Cancer Pain

4. Limitations

The Canadian Guideline is constrained by the paucity of evidence to support most of the topics where recommendations for practice were considered necessary and relevant. This required a heavy reliance on the opinion and expertise of the National Advisory Panel to develop recommendations. The literature searches for observational studies used broad terms and might have missed relevant studies. Of the 184 studies used to support the recommendations, only 62 were randomized trials; the remaining were observational studies. Given that the quality of the observational studies was not formally assessed, the grading system of the Canadian Task Force on Preventive Health Care (CTFPHC) was adapted (Woolf 1990).

Another limitation of the published evidence was that functional outcomes studied were predominantly “activity of daily living” and "quality of life" — other important outcomes such as return to work, productivity, and cognitive impairment were rarely reported. Potential long-term complications of opioid use (hypogonadism, opioid-induced hyperalgesia, addiction) cannot be ruled out even if the recommendations are strictly followed.

It addresses only one modality for managing CNCP — opioid therapy, and it does not discuss or provide guidance about selecting other options.

An attempt was made to maintain national perspective but NAP pointed out numerous instances where recommendations were dependent on access to resources not available in all parts of Canada (e.g., access to pain or addiction specialists, multi-disciplinary pain management teams, prescription-monitoring databases).

In spite of its narrow focus, it is a lengthy and detailed document, and will need to be translated into feasible and practical tools for day-to-day use by busy practitioners. Screening tools, e.g., the Opioid Risk Tool, are only valid when the patient’s reporting is accurate.

Finally, the group overseeing guideline development (NOUGG) represents medical regulatory authorities, and this could create concern that the Canadian Guideline will be used as a standard of practice rather than for its intended purpose as advice to assist physicians.