O'Connor 2008.

Methods	Randomised controlled clinical trial.
Participants	Randomised participants were aged between 21 to 64 and were recruited through media announcements, clinic publicity and referrals. Initially 61 potential participants were reduced to 41 and these 41 were all assigned to control in this Canadian study. One year later a further 69 potential participants were reduced to 48 and these were randomly assigned to group support (N = 24) or CBT plus group support (N = 24). Three participants dropped out prior to baseline and were not replaced. Only data relating to the randomised participants are used within this review. Therefore, the total number of participants in the trial was N = 45, with N = 23 intervention 1 and N = 22 for intervention 2.
Interventions	Intervention group 1: CBT, plus taper. CBT was administered in manualised form over 20 weeks. The therapy aimed to enhance self‐efficacy principally through normalizing expectations of withdrawal and attributions of withdrawal through boosting confidence in a) coping without BZD, b)coping with anxious inhibiting situations and through developing a belief in capacity to function autonomously from BZDs. Phase one was preparation (4 weeks), phase two was severance (16 weeks) and phase three was maintaining abstinence (duration unclear). Intervention group 2: Group support, plus taper. Group programme  comprised weekly meetings where exchanges took the form of open‐ended discussions on themes such as 'What is anxiety?'. No direct actions or strategy to deal with problems was suggested. Participants reflected on discussions and themes throughout the week. Each week a different theme was discussed.
Outcomes	The primary outcome measure was a successful taper at T1 which was further assessed by continuous success or failure 3 months post taper at T2. A completer was defined as a participant who completed the entire 20 week taper programme(T1). A succeeder (or responder) was defined as a participant who had ceased medication at 20 weeks. A relapse was defined as retaking medication at 3 months follow‐up (T2). The criteria for success was total abstinence from BZDs and a further follow‐up was performed at 7 to 15 months post T2 on those who had successfully tapered. A wide range of instruments was administered at the time points.
Notes	Funding source: The Fonds de la Recherche en Santé du Québec and the Conseil Québécois de la Recherche Sociale (grant 961227). Declaration of interest: Not reported.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	"After initial recruitment of 130 individuals some were assigned sequentially but not randomly to tapering or treatment as usual. Eventually, 48 were randomly assigned,  to either a group CBT or a non‐directive group support condition, on the basis of a random sequence generator".
Allocation concealment (selection bias)	Unclear risk	Method of allocation concealment not reported.
Blinding (performance bias and detection bias) All outcomes	Low risk	"All treating physicians included in the study were blind as to membership of the referred participants".
Blinding of participants and personnel (performance bias) All outcomes	Low risk	"All treating physicians included in the study were blind as to membership of the referred participants".
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Objective outcome was taper dose.Unlikely to have been influenced.
Blinding of outcome assessor (detection bias) subjective outcomes	Unclear risk	Subjective measures were mainly a series of validated instruments and it is difficult to say from the paper whether the measures were influenced.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	"A limitation of the group comparisons was that questionnaire measures were not available on all participants at follow up". Overall follow‐up for the primary outcome measure(successful/non‐successful taper) was 31/48.
Selective reporting (reporting bias)	Low risk	The study protocol is not available but the published report includes the expected outcome which was pre‐specified in the methods section.