Ahmadi 2003b.

Methods	Three‐group, randomised open‐label trial with participants randomised to treatment groups in consecutive numerical order by an investigational team. Participants were divided into treatment groups by dose and duration of buprenorphine misuse. Concealment of randomisation not stated.
Participants	Geographic region: Iran. N = 204. Mean age; 31 years (BMT), 31 years (MMT). 100% male. Inclusion criteria: Male gender, DSM‐IV diagnosis of opioid dependence, "daily use of injection buprenorphine for at least 6 months". Exclusion criteria: another medical condition, a diagnosis of alcohol dependence, prescribed anticonvulsants, neuroleptics or methadone during the previous month, or a score of 7 or higher on the Addiction Severity Index.
Interventions	24 weeks of maintenance, with fixed dosing. Buprenorphine (sublingual tablet) 5 mg daily, methadone 50 mg daily, or naltrexone 50 mg daily.
Outcomes	Retention in treatment.
Funding source	None reported.
Declarations of interest	None reported.
Notes	Offered weekly half‐hourly individual counselling sessions.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	High risk	"Randomised to treatment groups in consecutive numerical order".
Allocation concealment (selection bias)	High risk	"Randomised to treatment groups in consecutive numerical order".
Blinding (performance bias and detection bias) All outcomes	Low risk	Open‐label. Objective outcome measurement not influenced by lack of blinding.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Intention‐to‐treat.