Effect of cannabis use in people with chronic non-cancer pain prescribed opioids: findings from a 4-year prospective cohort study.

BACKGROUND: Interest in the use of cannabis and cannabinoids to treat chronic non-cancer pain is increasing, because of their potential to reduce opioid dose requirements. We aimed to investigate cannabis use in people living with chronic non-cancer pain who had been prescribed opioids, including their reasons for use and perceived effectiveness of cannabis; associations between amount of cannabis use and pain, mental health, and opioid use; the effect of cannabis use on pain severity and interference over time; and potential opioid-sparing effects of cannabis. METHODS: The Pain and Opioids IN Treatment study is a prospective, national, observational cohort of people with chronic non-cancer pain prescribed opioids. Participants were recruited through community pharmacies across Australia, completed baseline interviews, and were followed up with phone interviews or self-complete questionnaires yearly for 4 years. Recruitment took place from August 13, 2012, to April 8, 2014. Participants were asked about lifetime and past year chronic pain conditions, duration of chronic non-cancer pain, pain self-efficacy, whether pain was neuropathic, lifetime and past 12-month cannabis use, number of days cannabis was used in the past month, and current depression and generalised anxiety disorder. We also estimated daily oral morphine equivalent doses of opioids. We used logistic regression to investigate cross-sectional associations with frequency of cannabis use, and lagged mixed-effects models to examine temporal associations between cannabis use and outcomes. FINDINGS: 1514 participants completed the baseline interview and were included in the study from Aug 20, 2012, to April 14, 2014. Cannabis use was common, and by 4-year follow-up, 295 (24%) participants had used cannabis for pain. Interest in using cannabis for pain increased from 364 (33%) participants (at baseline) to 723 (60%) participants (at 4 years). At 4-year follow-up, compared with people with no cannabis use, we found that participants who used cannabis had a greater pain severity score (risk ratio 1·14, 95% CI 1·01-1·29, for less frequent cannabis use; and 1·17, 1·03-1·32, for daily or near-daily cannabis use), greater pain interference score (1·21, 1·09-1·35; and 1·14, 1·03-1·26), lower pain self-efficacy scores (0·97, 0·96-1·00; and 0·98, 0·96-1·00), and greater generalised anxiety disorder severity scores (1·07, 1·03-1·12; and 1·10, 1·06-1·15). We found no evidence of a temporal relationship between cannabis use and pain severity or pain interference, and no evidence that cannabis use reduced prescribed opioid use or increased rates of opioid discontinuation. INTERPRETATION: Cannabis use was common in people with chronic non-cancer pain who had been prescribed opioids, but we found no evidence that cannabis use improved patient outcomes. People who used cannabis had greater pain and lower self-efficacy in managing pain, and there was no evidence that cannabis use reduced pain severity or interference or exerted an opioid-sparing effect. As cannabis use for medicinal purposes increases globally, it is important that large well designed clinical trials, which include people with complex comorbidities, are conducted to determine the efficacy of cannabis for chronic non-cancer pain. FUNDING: National Health and Medical Research Council and the Australian Government.

Knowledge of Opioid Overdose and Attitudes to Supply of Take-Home Naloxone Among People with Chronic Noncancer Pain Prescribed Opioids.

Objective: Take-home naloxone (THN) is recommended in response to pharmaceutical opioid-related mortality. Some health professionals are reluctant to discuss THN for fear of causing offense. The aims of this study were to assess knowledge of opioid overdose and attitudes toward THN for opioid overdose reversal in people with chronic noncancer pain (CNCP). Design: Prospective cohort study. Setting: Australia, September to October 2015. Subjects: A subset of participants (N = 208) from a cohort of people prescribed restricted opioids for CNCP. Methods: Questions added in the two-year telephone interviews examined knowledge of overdose symptoms and attitudes toward community supply of naloxone. Associations with overdose risk factors and naloxone supply eligibility criteria with attitudes toward naloxone were explored. Results: Fourteen percent reported ever experiencing opioid overdose symptoms. Participants correctly identified fewer than half of the overdose signs and symptoms. After receiving information on naloxone, most participants (60%), thought it was a "good" or "very good" idea. Few participants reported that they would be "a little" (N = 21, 10%) or "very" offended (N = 7, 3%) if their opioid prescriber offered them naloxone. Positive attitudes toward THN were associated with male gender (odds ratio [OR] = 1.96, 95% confidence interval [CI] = 1.09-3.50), past year cannabis use (OR = 2.52, 95% CI = 1.03-6.16), and past year nicotine use (OR = 2.11, 95% CI = 1.14-3.91). Conclusions: Most participants had positive attitudes toward THN but low knowledge about opioid overdose symptoms. Strategies for educating patients and their caregivers on opioid toxicity are needed. THN may be best targeted toward those with risk factors in terms of overdose prevention and acceptability.

Health service utilisation by people living with chronic non-cancer pain: findings from the Pain and Opioids IN Treatment (POINT) study.

Objective The aims of the present study were to describe the use, and barriers to the use, of non-medication pain therapies and to identify the demographic and clinical correlates of different non-opioid pain treatments. Methods The study was performed on a cohort (n=1514) of people prescribed pharmaceutical opioids for chronic non-cancer pain (CNCP). Participants reported lifetime and past month use of healthcare services, mental and physical health, pain characteristics, current oral morphine equivalent daily doses and financial and access barriers to healthcare services. Results Participants reported the use of non-opioid pain treatments, both before and after commencing opioid therapy. Services accessed most in the past month were complementary and alternative medicines (CAMs; 41%), physiotherapy (16%) and medical and/or pain specialists (15%). Higher opioid dose was associated with increased financial and access barriers to non-opioid treatment. Multivariate analyses indicated being younger, female and having private health insurance were the factors most commonly associated with accessing non-opioid treatments. Conclusions Patients on long-term opioid therapy report using multiple types of pain treatments. High rates of CAM use are concerning given limited evidence of efficacy for some therapies and the low-income status of most people with CNCP. Financial and insurance barriers highlight the importance of considering how different types of treatments are paid for and subsidised. What is known about the topic? Given concerns regarding long-term efficacy, adverse side-effects and risk of misuse and dependence, prescribing guidelines recommend caution in prescribing pharmaceutical opioids in cases of CNCP, typically advising a multidisciplinary approach to treatment. There is a range of evidence supporting different (non-drug) treatment approaches for CNCP to reduce pain severity and increase functioning. However, little is known about the non-opioid treatments used among those with CNCP and the demographic and clinical characteristics that may be associated with the use of different types of treatments. Understanding the use of non-drug therapy among people with CNCP is crucial given the potential to improve pain control for these patients. What does this paper add? The present study found that a wide range of non-opioid treatments was accessed by the study sample, both before and after commencing opioids, indicating that in this sample opioids were not the sole strategy used for pain management. The most common treatment (other than opioids) was CAM, reported by two-fifths of the sample. Having private health insurance was associated with increased use of non-opioid treatments for pain, highlighting the importance of considering how treatments are paid for and potential financial barriers to effective treatments. What are the implications for practitioners? Patients' beliefs and financial barriers may affect the uptake of different treatments. Many patients may be using complementary and alternative approaches with limited evidence to support their use, highlighting the need for clinicians to discuss with patients the range of prescribed and non-prescribed treatments they are accessing and to help them understand the benefits and risks of treatments that have not been tested sufficiently, or have inconsistent evidence, as to their efficacy in improving pain outcomes.