Silverman 2012.

Study characteristics
Methods	Study design: cluster RCT Study grouping: parallel group Allocation concealment: method of allocation concealment not specified Randomisation method: consumers in 16 sessions were randomised into experimental or control conditions by session. The numbers 1–16 were randomised into 2 groups and each group was assigned to a condition. Participants were allocated to the group of the first session they attended.
Participants	Baseline characteristics MT + SC Gender male: 22 (54.2%) Age: 44.6 years Sample size: 48 SC (wait‐list control) Gender male: 26 (50.9%) Age: 43.26 years Sample size: 51 Overall Gender male: 48 (48.5%) Age: 43.93 years Sample size: 99 Inclusion criteria: inpatient status on detoxification unit Exclusion criteria: none specified Pretreatment: no statistically significant differences between groups at baseline in regard to: number of inpatients who volunteered to be research participants; total number of inpatients in each session; participants' ages; number of times participants had been admitted to a rehabilitation/detoxification facility. No significant differences between groups in gender; race/ethnicity; drug of choice. Confirmation of population eligibility (from study author): author confirmed by email that participants had diagnosis of SUD.
Interventions	Intervention characteristics MT + SC Description: MT songwriting session with focus on theme of change (using blues genre), following functional CBT manual Session length: 45 minutes Frequency: single session Duration of treatment: single session SC (wait‐list control) Description: wait‐list control Session length: not applicable Frequency: not applicable Duration of treatment: not applicable
Outcomes	Motivation for treatment – Circumstances, Motivation, and Readiness Scales for Substance Abuse Treatment, Motivation subscale Outcome type: continuous outcome Reporting: fully reported Scale: 5‐point Likert‐type scale for each item Direction: higher is better Data value: endpoint Readiness for treatment – Circumstances, Motivation, and Readiness Scales for Substance Abuse Treatment, Readiness subscale Outcome type: continuous outcome Reporting: fully reported Scale: 5‐point Likert‐type scale for each item Direction: higher is better Data value: endpoint
Identification	Sponsorship source: none Country: USA Setting: inpatient detoxification unit of a large teaching hospital Author's name: Michael J Silverman Institution: University of Minnesota Declarations of interest: no conflicts of interest reported
Notes	Email (13 September 2017) from author confirmed that participants met criteria for SUD.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Judgement comment: methods of sequence generation not specified.
Allocation concealment (selection bias)	Unclear risk	Judgement comment: method for allocation concealment not specified.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Judgement comment: reasons for missing outcome data not specified.
Selective reporting (reporting bias)	Low risk	Judgement comment: no selective outcome reporting.
Blinding of participants and providers (performance bias) (subjective outcomes)	Low risk	Judgement comment: not possible to blind participants and providers to MT intervention.
Blinding of outcome assessor (detection bias) (subjective outcomes)	Unclear risk	Judgement comment: not possible to blind outcome assessor for self‐report outcomes, though measurement not likely to be influenced differentially between groups.