Fischer 1999.

Methods	Two‐group, open‐label, randomised clinical trial, with participants randomised "externally . . . independent of the investigators", but the method of concealment of allocation is unstated.
Participants	Geographic region: Austria. N = 60. Age range: 18 ‐ 39 years. 68% male. Inclusion criteria: DSM‐IV diagnosis of opioid dependence, aged 18 ‐ 45 years, willing to follow the maintenance programme and avoid using illegal drugs wherever possible. Exclusion criteria: dependence on other drugs (except cannabis), pregnancy, HIV positivity or seriously illness.
Interventions	24 weeks of maintenance, flexible dosing. Buprenorphine (sublingual tablet) mean dose 7.5 mg/day (range 2 mg to 8 mg). Methadone mean dose 63 mg/d (range 20 mg to 80 mg).
Outcomes	Retention in treatment, urinalysis for opioids, cocaine, and benzodiazepines.
Funding source	None reported.
Declarations of interest	None reported.
Notes	Prior to entering trial, all participants were screened for 1 week and maintained with slow‐release oral morphine (Kapanol CSR). Weekly group psychotherapy was provided.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Not specified.
Allocation concealment (selection bias)	Low risk	"Randomised externally using a source independent of investigators".
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.