Hjorthoj 2013.

Methods	Allocation: randomised. Design: single‐centre. Duration: 10 months: 6 months treatment, 4‐month follow‐up. Setting: Hospital, community and early intervention services. Location: Copenhagen, Denmark.
Participants	Diagnosis: ICD‐10 schizophrenia spectrum psychosis (F2) and ICD‐10 cannabis use disorder. N = 103. Age: mean ˜ 21 years (range 17‐42). Sex: 78 M, 25 F. Ethnicity: Not stated. Inclusion criteria: cannabis use, those dependent on alcohol, opioids or cocaine were excluded.
Interventions	1. Psychosocial intervention: CBT + MI, CapOpus consisted of individual and group based motivational interviewing and CBT with 24 sessions, 1‐2 weekly over 6 months and incorporates both family and case manager. N = 52. 2. Standard care: TAU. N = 51.
Outcomes	Leaving the study early: lost to treatment, lost to evaluation. Substance use: number of cannabis‐using days in the past month. Quality of life/life satisfaction: Client satisfaction (CSQ). Unable to use Substance use: days cannabis use, joints/30 days (skewed data). Mental state: PANSS 6 months and 10 months (data skewed).
Notes	ITT analysis, missing data were estimated for each analysis using log‐linear replacement. Authors kindly provided additional data.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	computer‐generated random sequence stratified by cannabis use per day and type of TAU (some had case management or ACT depending on referral source), block size varied between 6, 8 and 10.
Allocation concealment (selection bias)	Low risk	Researcher not involved in the study generated the sequence, was known only to the Copenhagen Trial unit.
Blinding of participants and personnel (performance bias) All outcomes	High risk	Clinician‐/participant‐mediated and participants and personnel not blinded. It is not possible to blind a psychosocial intervention.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Raters blind to treatment assignment.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Lost to follow‐up: 34% (35/103) 10 months. Detailed flow chart provided, reasons for missing values are provided for each group. Full ITT analysis provided with missing values handled by multiple imputations, which can bias studies so rated unclear.
Selective reporting (reporting bias)	Low risk	Outcomes fully reported and were not different to trial protocol.
Other bias	Low risk	No evidence other bias occurring.