Madigan 2013.

Methods	Allocation: randomised. Design: single‐centre (3 sites). Duration: 12 months. Setting: inpatients and community. Location: Dublin, Ireland.
Participants	Diagnosis: DSM‐IV diagnosis of psychosis (schizophrenia, n = 38; other psychosis, n = 30) major depression (n = 6) and bipolar disorder (n = 14) and DSM‐IV current cannabis dependence. N = 88. Age: mean ˜ 28 years. Sex: 69 M, 19 F. Ethnicity: Not stated (homogenous group). Inclusion criteria: without learning disability or organic brain damage.
Interventions	1. Psychosocial intervention: CBT + MI group sessions once per week for 12 weeks and invited back 6 weeks later (week 18) for a booster session. Interventions were held in community setting. N = 59.* 2. Standard care: TAU included care from multi‐disciplinary team, 5 patients had counselling for opiate more than one year prior to the present trial. N = 29.
Outcomes	Leaving the study early: lost to treatment (3 months), lost to evaluation (9 months). Substance use: frequency of cannabis use last 30 days. Global state: GAF global functioning. Quality of life/life satisfaction: subjective quality of life (WHOQOL, BREF). Unable to use Mental State: SANS. SAPS (positive, negative), Calgary Depression Scale for Schizophrenia (skewed data).
Notes	* Note: 2:1 randomisation to CBT/MI arm. A token voucher was given to participants to cover costs of attendance of assessments.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer‐generated, block randomised, 2:1 (CBT/MI:TAU) ratio.
Allocation concealment (selection bias)	Unclear risk	Randomisation was conducted by a researcher uninvolved in the provision or assessment of interventions. Concealment not described in sufficient detail to allow a definite judgement.
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 of clinical outcomes blind to treatment allocation.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Lost to follow‐up: 42% (37/88) 1 year. Similar reasons for missing data across groups. Missing values were not imputed for ITT analysis.
Selective reporting (reporting bias)	Unclear risk	Insufficient information to permit judgement of 'yes' or 'no' as no protocol was available.
Other bias	Low risk	No evidence other bias occurring.