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

Cluster 1: Deciding to Initiate Opioid Therapy

R01. Recommendation Statement

No. Recommendation Keyword
R01 Before initiating opioid therapy, ensure comprehensive documentation of the patient’s pain condition, general medical condition and psychosocial history (Grade C), psychiatric status, and substance use history. (Grade B). Comprehensive assessment
  • R01. Discussion
  • R01. Summary of Peer-Reviewed Evidence

R01. Discussion

1. Comprehensive Knowledge of the Patient

1.1 Pain Condition

Comprehensive knowledge of the patient’s pain condition includes:

  • Thorough history and physical examination to determine the type, cause and nature of the pain, including questions about past investigations and interventions for pain including medication trials
  • Estimate of the pain intensity and the functional impairment that arises from it (impact of pain on work, school, home and leisure activities)
  • Diagnosis

1.2 General Medical and Psychosocial History

  • General medical history includes questions about general physical health, emotional health, and medication use.
  • Psychosocial history includes information regarding: living arrangements, family/social support, family obligations, work status.

1.3 Psychiatric Status

Psychiatric status includes information regarding:

  • The patient’s current and past history of psychiatric disorders and treatments; (also see Recommendation 20 for more details about prescribing options for patients with psychiatric disorders)
  • Family history of psychiatric disorders.

1.4 Substance Use History

Substance use history includes questions about:

  • Current, past, and family history of substance use, abuse, and addiction (alcohol, marijuana, tobacco, benzodiazepines, opioids, cocaine, amphetamines, barbiturates, hallucinogens, and solvents), and
  • Any attendance at a treatment program for addiction. (See Appendix B-1 for tools and interview guides to assist in taking a substance use history.)

2. Documentation

Maintain detailed records documenting the assessment of the patient, treatment plan, discussion of risks and benefits, informed consent, opioids prescribed, and outcomes.

R01. Summary of Peer-Reviewed Evidence

1. Opioid addiction is estimated to have an overall prevalence of 3.3% in patients receiving opioids for CNCP, with a wide variation between clinics and regions. Aberrant drug-related behaviours have a much higher prevalence. The major risk factor for addiction is a current or past history of addiction.

The prevalence of aberrant drug-related behaviours and addiction among patients on LTOT is not certain. In a recent systematic review of 67 studies (Fishbain 2008), the prevalence of clinically diagnosed opioid abuse or addiction was reported as 3.3% in those studies that included patients with a history of substance abuse. The prevalence of aberrant drug-related behaviours was 11.5% (range 0–44%). The percent of urine drug screens with illicit drugs present was 14.5%, while the percent of urine drug screens with a non-prescribed opioid or no opioid present (suggesting possibly diversion) was 20.4%.

The corresponding figures were much lower for studies that excluded patients with a history of substance abuse, confirming that a past history is an important risk factor for the development of abuse or addiction. Other risk factors have been identified in individual studies, such as anxiety disorders, post-traumatic stress disorder and personality disorders (Wilsey 2008).

This review (Fishbain 2008) and the studies on which it is based have several limitations. There was no breakdown of the types of clinics studied or the dates of the study (evidence suggests the incidence of opioid addiction is increasing). The diagnosis of addiction is dependent on the clinician’s judgment—aberrant drug-related behaviours and urine drug screen results are only a proxy measure of addiction. Aberrant drug-related behaviours could indicate opioid addiction but they also might reflect inadequately treated pain, or abuse of non-opioid drugs, e.g., cocaine.

The prevalence of aberrant drug-related behaviours appears to vary widely between regions and clinics. One study of two primary-care clinics found a prevalence of opioid aberrant drug-related behaviours of 24% and 31% (Reid 2002), while another found a prevalence of 7% among depressed primary-care patients (Roeloffs 2002). Specialty medical or surgical clinics, which tend to follow older patients with organic pain conditions, have found low rates of opioid aberrant drug-related behaviours (Mahowald 2005). There are also striking regional variations.

It is difficult to generalize from these studies, as they 1) were usually based in a specific clinic setting, 2) are limited by selection biases, and 3) often used proxy measures for addiction (drug-seeking behaviours) rather than comprehensive patient assessment.

2. The prevalence of problematic substance use, including opioids, non-opioid substances and alcohol, is higher among patients on long-term opioid therapy for CNCP than in the general population.

One large nationally representative cross-sectional survey of over 9,000 subjects found that the prevalence of problematic substance use was higher among those on prescribed opioids than among non-opioid users (Edlund 2007). This included problematic use of alcohol and non-opioid substances as well as opioids. Controlling for co-morbid mental disorders, the association with non-opioid substances disappeared, suggesting that the higher prevalence of mental disorders in opioid users mediates their higher risk for problematic substance use.