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

Campbell, G, Hall, WD, Peacock, A, Lintzeris, N, Bruno, R ORCID: 0000-0001-6673-833X, Larance, B, Nielsen, S, Cohen, M, Chan, G, Mattick, RP, Blyth, F, Shanahan, M, Dobbins, T, Farrell, M and Degenhardt, L 2018 , 'Effect of cannabis use in people with chronic non-cancer pain prescribed opioids: findings from a 4-year prospective cohort study' , The Lancet Public Health, vol. 3, no. 7 , e341-e350 , doi:

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Background: Interest in the use of cannabis and cannabinoids to treat chronic non-cancer pain is increasing, becauseof their potential to reduce opioid dose requirements. We aimed to investigate cannabis use in people living withchronic non-cancer pain who had been prescribed opioids, including their reasons for use and perceivedeffectiveness 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 ofcannabis.Methods: The Pain and Opioids IN Treatment study is a prospective, national, observational cohort of people withchronic non-cancer pain prescribed opioids. Participants were recruited through community pharmacies acrossAustralia, completed baseline interviews, and were followed up with phone interviews or self-completequestionnaires yearly for 4 years. Recruitment took place from August 13, 2012, to April 8, 2014. Participants wereasked 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 thepast month, and current depression and generalised anxiety disorder. We also estimated daily oral morphineequivalent doses of opioids. We used logistic regression to investigate cross-sectional associations with frequency ofcannabis use, and lagged mixed-effects models to examine temporal associations between cannabis use andoutcomes.Findings: 1514 participants completed the baseline interview and were included in the study fromAug 20, 2012, to April 14, 2014. Cannabis use was common, and by 4-year follow-up, 295 (24%) participants hadused cannabis for pain. Interest in using cannabis for pain increased from 364 (33%) participants (at baseline) to723 (60%) participants (at 4 years). At 4-year follow-up, compared with people with no cannabis use, we found thatparticipants who used cannabis had a greater pain severity score (risk ratio 1·14, 95% CI 1·01–1·29, for lessfrequent 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), andgreater generalised anxiety disorder severity scores (1·07, 1·03–1·12; and 1·10, 1·06–1·15). We found no evidenceof a temporal relationship between cannabis use and pain severity or pain interference, and no evidence thatcannabis 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 painand lower self-efficacy in managing pain, and there was no evidence that cannabis use reduced pain severity orinterference or exerted an opioid-sparing effect. As cannabis use for medicinal purposes increases globally, it isimportant that large well designed clinical trials, which include people with complex comorbidities, are conducted todetermine the efficacy of cannabis for chronic non-cancer pain.

Item Type: Article
Authors/Creators:Campbell, G and Hall, WD and Peacock, A and Lintzeris, N and Bruno, R and Larance, B and Nielsen, S and Cohen, M and Chan, G and Mattick, RP and Blyth, F and Shanahan, M and Dobbins, T and Farrell, M and Degenhardt, L
Journal or Publication Title: The Lancet Public Health
Publisher: Elsevier, Ltd.
ISSN: 2468-2667
DOI / ID Number:
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Copyright 2018 The Authors. Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0)

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