Abstract: Six studies (four RCTs and two prospective observational cohort studies), involving 7999 participants comparing supervised OST treatment with unsupervised treatment, met the inclusion criteria. The risk of bias was generally moderate across trials, but the results reported on outcomes that we planned to consider were limited. Overall, we judged the quality of the evidence from very low to low for all the outcomes. We found no difference in retention at any duration with supervised compared to unsupervised dosing (RR 0.99, 95% CI 0.88 to 1.12, 716 participants, four trials, low-quality evidence) or in retention in the shortest follow-up period, three months (RR 0.94; 95% CI 0.84 to 1.05; 472 participants, three trials, low-quality evidence). Additional data at 12 months from one observational study found no difference in retention between groups (RR 0.94, 95% CI 0.77 to 1.14; n = 300).There was no difference in abstinence at the end of treatment (self-reported drug use) (67% versus 60%, P = 0.33, 293 participants, one trial, very low-quality evidence); and in diversion of medication (5% versus 2%, 293 participants, one trial, very low-quality evidence). Regarding our secondary outcomes, we did not found a difference in the incidence of adverse effects in the supervised compared to unsupervised control group (RR 0.63; 96% CI 0.10 to 3.86; 363 participants, two trials, very low-quality evidence). Data on severity of dependence were very limited (244 participants, one trial) and showed no difference between the two approaches. Data on deaths were reported in two studies. One trial reported two deaths in the supervised group (low-quality evidence), while in the cohort study all-cause mortality was found lower in regular supervision group (crude mortality rate 0.60 versus 0.81 per 100 person-years), although after adjustment insufficient evidence existed to suggest that regular supervision was protective (mortality rate ratio = 1.23, 95% CI = 0.67 to 2.27). No studies reported pain symptoms, drug craving, aberrant opioid-related behaviours, days of unsanctioned opioid use and overdose. Take-home medication strategies are attractive to treatment services due to lower costs, and place less restrictions on clients, but it is unknown whether they may be associated with increased risk of diversion and unsanctioned use of medication. There is uncertainty about the effects of supervised dosing compared with unsupervised medication due to the low and very low quality of the evidence for the primary outcomes of interest for this review. Data on defined secondary outcomes were similarly limited. More research comparing supervised and take-home medication strategies is needed to support decisions on the relative effectiveness of these strategies. The trials should be designed and conducted with high quality and over a longer follow-up period to support comparison of strategies at different stages of treatment. In particular, there is a need for studies assessing in more detail the risk of diversion and safety outcomes of using supervised OST to manage opioid dependence.

Plain-language summary: We identified six studies involving 7999 people receiving treatment with methadone (7786 people) or buprenorphine–naloxone (213 people ) for opioid dependence. Four of the studies were randomised controlled trials (clinical studies where people are randomly put into one of two or more treatment groups), while the other two studies followed groups of people over time. Four of the studies were funded by the National Institutes for Health Research and by the Health Research Board, with one study not reporting the funding source. One study was also funded by the drug company of buprenorphine–naloxone. At three or more months follow-up, this review found no evidence on benefit of the supervised dosing with respect to keep people in treatment, or reduce opioid use, mortality reduction and adverse drug events. One study found that supervised dosing led to a reduction of diversion. None of the studies assessed the effect of supervised dosing on pain symptoms, drug craving, days of unsanctioned opioid use, overdose and hospitalisation. We are unable to make any conclusion about the effectiveness of supervised dosing compared to dispensing of medication as take-home doses, in the context of OST. Further research is required to determine the effectiveness of supervised or take-home dosing in OST. Overall, the studies were moderately well-conducted, but there was a small number of studies reporting outcomes of interest, therefore insufficient to evaluate the efficacy of intervention such as diversion, opoid use reduction, retention in treatment and frequency of unsanctioned opioid use, Furthermore, low rates of occurrence of some events between studies resulted in the overall quality of the evidence being assessed as low and very low. This indicates that further evidence would be likely to change the estimates of relative effect made in this review.