Silverman 2016a.

Study characteristics
Methods	Study design: cluster RCT Study grouping: parallel group Allocation concealment: method for allocation concealment not specified Randomisation method: participants in 24 sessions were randomised into 1 of 4 conditions by session. The numbers 1–24 were randomised into 4 groups and each group was assigned to a condition. Participants were allocated to the group of the first session they attended. If a participant who had already participated in the study was readmitted due to relapse, she or he was eligible for the therapy session but ineligible for research study inclusion.
Participants	Baseline characteristics MT (lyric analysis with live music) + SC Gender male: 21 (57%) Age: 37.59 years Sample size: 37 MT (lyric analysis with recorded music) + SC Gender male: 16 (53%) Age: 38.87 years Sample size: 30 Verbal therapy + SC Gender male: 15 (50%) Age: 39.10 years Sample size: 30 Recreational music + SC Gender male: 21 (63%) Age: 42.18 years Sample size: 33 Overall Gender male: 73 (56%) Age: 39.44 years Sample size: 130 Inclusion criteria: inpatient on a detoxification unit Exclusion criteria: none mentioned Pretreatment: no significant differences between groups in regard to: number of participants taking part in each session who volunteered to be research participants; total number of participants in each session; age; number of days had been an inpatient on the unit; total number of times participants had been admitted to a rehabilitation/detoxification facility. Confirmation of population eligibility (from study author): author confirmed that participants had diagnosis of SUD.
Interventions	Intervention characteristics MT (lyric analysis with live music) + SC Description: MT consisting of scripted educational lyric analysis session led by music therapist, and focused on supports in the community and coping skills. Song that was used as a basis for lyric analysis was played live by music therapist using acoustic guitar for accompaniment. Session length: approximately 45 minutes Frequency: single session Duration of treatment: single session MT (lyric analysis with recorded music) + SC Description: MT consisting of scripted educational lyric analysis session led by music therapist, and focused on supports in the community and coping skills. The song used as a basis for lyric analysis was a prerecorded version by the original artists. Session length: approximately 45 minutes Frequency: single session Duration of treatment: single session Verbal therapy + SC Description: a verbal‐based supportive session consisting of a scripted educational session concerning supports in the community and coping skills. No music was used. Session length: approximately 45 minutes Frequency: single session Duration of treatment: single session Recreational music + SC Description: rock and roll bingo game with discussion based on songs, artists, and memories associated with the music. Implemented by a music therapist. Session length: approximately 45 minutes Frequency: single session Duration of treatment: single session
Outcomes	Not used: working alliance (WAI‐S); trust in therapist (Wake Forest Physician Trust Scale)
Identification	Sponsorship source: none Country: USA Setting: inpatient detoxification unit Author's name: Michael J Silverman Institution: University of Minnesota Email: silvermj@umn.edu Address: School of Music, University of Minnesota, Minneapolis, Minnesota, USA 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: participants in 24 sessions were randomised into 1 of 4 conditions by session. The numbers 1–24 were randomised into 4 groups and each group was assigned to a condition. Participants were allocated to the group of the first session they attended.
Allocation concealment (selection bias)	Unclear risk	Judgement comment: insufficient information about allocation concealment to permit judgement.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Judgement comment: missing outcome data balanced in numbers across intervention groups, with similar reasons for missing data across groups. Reasons for missing outcome data unlikely to be related to true outcome.
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.