Buprenorphine versus methadone for the treatment of opioid dependence: a systematic review and meta-analysis of randomised and observational studies.

BACKGROUND: Opioid dependence is associated with substantial health and social burdens, and opioid agonist treatment (OAT) is highly effective in improving multiple outcomes for people who receive this treatment. Methadone and buprenorphine are common medications provided as OAT. We aimed to examine buprenorphine compared with methadone in the treatment of opioid dependence across a wide range of primary and secondary outcomes. METHODS: We did a systematic review and meta-analysis in accordance with GATHER and PRISMA guidelines. We searched Embase, MEDLINE, CENTRAL, and PsycINFO from database inception to Aug 1, 2022; clinical trial registries and previous relevant Cochrane reviews were also reviewed. We included all RCTs and observational studies of adults (aged ≥18 years) with opioid dependence comparing treatment with buprenorphine or methadone. Primary outcomes were retention in treatment at 1, 3, 6, 12, and 24 months, treatment adherence (measured through doses taken as prescribed, dosing visits attended, and biological measures), or extra-medical opioid use (measured by urinalysis and self-report). Secondary outcomes were use of benzodiazepines, cannabis, cocaine, amphetamines, and alcohol; withdrawal; craving; criminal activity and engagement with the criminal justice system; overdose; mental and physical health; sleep; pain; global functioning; suicidality and self-harm; and adverse events. Single-arm cohort studies and RCTs that collected data on buprenorphine retention alone were also reviewed. Data on study, participant, and treatment characteristics were extracted. Study authors were contacted to obtain additional data when required. Comparative estimates were pooled with use of random-effects meta-analyses. The proportion of individuals retained in treatment across multiple timepoints was pooled for each drug. This study is registered with PROSPERO (CRD42020205109). FINDINGS: We identified 32 eligible RCTs (N=5808 participants) and 69 observational studies (N=323 340) comparing buprenorphine and methadone, in addition to 51 RCTs (N=11 644) and 124 observational studies (N=700 035) that reported on treatment retention with buprenorphine. Overall, 61 studies were done in western Europe, 162 in North America, 14 in north Africa and the Middle East, 20 in Australasia, five in southeast Asia, seven in south Asia, two in eastern Europe, three in central Europe, one in east Asia, and one in central Asia. 1 040 827 participants were included in these primary studies; however, gender was only reported for 572 111 participants, of whom 377 991 (66·1%) were male and 194 120 (33·9%) were female. Mean age was 37·1 years (SD 6·0). At timepoints beyond 1 month, retention was better for methadone than for buprenorphine: for example, at 6 months, the pooled effect favoured methadone in RCTs (risk ratio 0·76 [95% CI 0·67-0·85]; I·=74·2%; 16 studies, N=3151) and in observational studies (0·77 [0·68-0·86]; I·=98·5%; 21 studies, N=155 111). Retention was generally higher in RCTs than observational studies. There was no evidence suggesting that adherence to treatment differed with buprenorphine compared with methadone. There was some evidence that extra-medical opioid use was lower in those receiving buprenorphine in RCTs that measured this outcome by urinalysis and reported proportion of positive urine samples (over various time frames; standardised mean difference -0·20 [-0·29 to -0·11]; I·=0·0%; three studies, N=841), but no differences were found when using other measures. Some statistically significant differences were found between buprenorphine and methadone among secondary outcomes. There was evidence of reduced cocaine use, cravings, anxiety, and cardiac dysfunction, as well as increased treatment satisfaction among people receiving buprenorphine compared with methadone; and evidence of reduced hospitalisation and alcohol use in people receiving methadone. These differences in secondary outcomes were based on small numbers of studies (maximum five), and were often not consistent across study types or different measures of the same constructs (eg, cocaine use). INTERPRETATION: Evidence from trials and observational studies suggest that treatment retention is better for methadone than for sublingual buprenorphine. Comparative evidence on other outcomes examined showed few statistically significant differences and was generally based on small numbers of studies. These findings highlight the imperative for interventions to improve retention, consideration of client-centred factors (such as client preference) when selecting between methadone and buprenorphine, and harmonisation of data collection and reporting to strengthen future syntheses. FUNDING: Australian National Health and Medical Research Council.

A protocol for a discrete choice experiment: understanding patient medicine preferences for managing chronic non-cancer pain.

INTRODUCTION: High rates of chronic non-cancer pain (CNCP), concerns about adverse effects including dependence among those prescribed potent pain medicines, the recent evidence supporting active rather than passive management strategies and a lack of funding for holistic programme have resulted in challenges around decision making for treatment among clinicians and their patients. Discrete choice experiments (DCEs) are one way of assessing and valuing treatment preferences. Here, we outline a protocol for a study that assesses patient preferences for CNCP treatment. METHODS AND ANALYSIS: A final list of attributes (and their levels) for the DCE was generated using a detailed iterative process. This included a literature review, a focus group and individual interviews with those with CNCP and clinicians who treat people with CNCP. From this process a list of attributes was obtained. Following a review by study investigators including pain and addiction specialists, pharmacists and epidemiologists, the final list of attributes was selected (number of medications, risk of addiction, side effects, pain interference, activity goals, source of information on pain, provider of pain care and out-of-pocket costs). Specialised software was used to construct an experimental design for the survey. The survey will be administered to two groups of participants, those from a longitudinal cohort of patients receiving opioids for CNCP and a convenience sample of patients recruited through Australia's leading pain advocacy body (Painaustralia) and their social media and website. The data from the two participant groups will be initially analysed separately, as their demographic and clinical characteristics may differ substantially (in terms of age, duration of pain and current treatment modality). Mixed logit and latent class analysis will be used to explore heterogeneity of responses. ETHICS AND DISSEMINATION: Ethics approval was obtained from the University of New South Wales Sydney Human Ethics committee HC16511 (for the focus group discussions, the one-on-one interviews and online survey) and HC16916 (for the cohort). A lay summary will be made available on the National Drug and Alcohol Research Centre website and Painaustralia's website. Peer review papers will be submitted, and it is expected the results will be presented at relevant pain management conferences nationally and internationally. These results will also be used to improve understanding of treatment goals between clinicians and those with CNCP.

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.