Study	Reason for exclusion
Audier 2011	Allocation: not randomised. Intervention: money for taking medication; not SUD focused.
Bachmann 1997	Allocation: not randomised.
Bagoien 2013	Allocation: randomised. Participants: not severely mentally ill; not all participants had a current drug and alcohol use problem.
Barkhof 2013	Allocation: not randomised
Barrowclough 2006b	Allocation: randomised. Participants: people with severe mental illness; substance misuse not identified as the primary problem.
Battersby 2013	Allocation: randomised. Participants: veterans who misused alcohol (AUDIT > 8) and who also had a psychiatric or medical condition. Not all participants had a serious psychotic illness (many had PTSD, panic or GAD).
Bechdolf 2004	Allocation: randomised. Participants: people with schizophrenia and a primary diagnosis of drug and alcohol dependence were excluded; no information provided on any participants with a dual diagnosis.
Beebe 2012	Allocation: randomised. Participants: people with schizophrenia and co‐occurring substance use disorders. Intervention: MI to increase exercise, not to reduce substance use.
Bell 2011	Allocation: randomised. Intervention: cognitive remediation, not SUD focused.
Bennett 2001	Allocation: not a randomised trial.
Bowen 2000	Allocation: randomised. Participants: not severely mentally ill (panic disorder with or without agoraphobia).
Brooner 2013	Allocation: randomised. Participants: received routine methadone maintenance, low percentage of participants had a comorbid psychotic disorder (< 5%).
Brown 2015	Allocation: randomised. Participants: adolescents (aged 13‐17) with psychiatric comorbidity, non‐adult population. Patients were excluded it they had a psychotic disorder.
Carey 2004	Allocation: randomised. Participants: people with severe mental illness; not all patients had a current drug and alcohol use problem.
Castle 2002	No usable data. Email from author confirmed study abandoned; not enough participants to publish the results.
Clarke 2000	Allocation: randomised. Participants: people with severe mental illness; not all participants had a current drug and alcohol use problem.
Clausen 2016	Allocation: not randomised
de Waal 2015	Allocation: randomised. Intervention: to reduce victimisation in patients with a dual diagnosis. Not a intervention to reduce SUD.
DeMarce 2008	Allocation: randomised. Participants: substance abusers with co‐occurring psychiatric disorder. No description of seriousness of psychiatric diagnoses. Intervention: participants received a behavioural continuing care adherence intervention involving contracting, prompting and reinforcing attendance or standard treatment.
Drake 2004a	Allocation: original sample randomised. Participants: people with severe mental illness and substance misuse. Interventions: psychosocial. Outcomes: no usable data (results from control group not reported).
Drake 2006	Allocation: original sample randomised. Participants: people with severe mental illness and substance misuse. Interventions: psychosocial. Outcomes: no usable data (results from control group not reported).
Drebing 2005	Allocation: randomised. Participants: only 11% (n = 2) of the veterans had a psychotic diagnosis, 74% had an affective disorder and 58% had an anxiety disorder. Did not fulfil the criteria for serious mental illness.
Drebing 2007	Allocation: randomised. Participants: only 9% of the veterans had a psychotic diagnosis, 80% had major depression and 53% were given a PTSD diagnosis.
Eberhard 2009	Allocation: randomised. Participants: ˜40% had affective disorder, ˜23% anxiety disorder and ˜13% PTSD, 7% personality disorder. All patients were non‐psychotic.
Faber 2012	Allocation: subanalysis from a larger randomised trial. Participants: first‐episode psychosis, but substance use was not an inclusion criteria. Intervention: not a psychosocial intervention focused on reducing substance use.
Fiszdon 2016	Allocation: randomised. Participants: people meeting criteria for substance abuse in last 30 days excluded, not a dual diagnosis population.
Gaughran 2017	Allocation: randomised care coordinators (n = 104) and the patients they cared for (406). Participants: outpatients with a psychotic disorder; Not all participants had a SUD. Intervention: to improve lifestyle choices, improve diet and reduce smoking (IMPACT health promotion). Where applicable, intervention targeted alcohol, cannabis and other illegal substances.
Gleesen 2009	Allocation: randomised. Participants: young people with first‐episode psychosis; not all patients had a current or past drug or alcohol use problem. Intervention: individual and family CBT focused on relapse prevention, not SUD focused.
Goldstein 2005	Allocation: randomised. Participants: only two participants had a diagnosis of schizophrenia.
Harrison 2017	Allocation: not randomised.
Havassy 2000	Allocation: randomised. Participants: people with severe mental illness and substance misuse. Interventions: two case0management programmes; no specific substance misuse treatment.
Herman 2000	Allocation: randomised. Participants: people with severe mental illness and substance misuse. Interventions: psychosocial. Outcomes: no usable data.
Hulse 2002	Allocation: randomised. Participants: not all severely mentally ill (10% psychotic); 26% did not have a dual diagnosis.
ISRCTN58667926	Allocation: randomised. Participants: serious mental illness; substance use disorder not listed as an inclusion criteria.
James 2004	Allocation: not randomised (alternate allocation).
Jerrell 2000	Allocation: randomised. Participants: people with severe mental illness and a co‐occurring substance disorder. Interventions: day treatment integrating mental health and substance use symptoms; community group meetings, skill‐building, 12‐step groups, relapse prevention skills and case management versus treatment as usual. Outcomes: no usable data ‐ control group data not available.
Kelly 2002	Allocation: not randomised.
Kidorf 2013	Allocation: randomised. Participants: attending methadone clinic who also had a psychiatric disorder; none were diagnosed with schizophrenia. Many had PTSD or antisocial personality disorder. Intervention: not a SUD psychosocial intervention
Killackey 2013	Allocation: randomised. Participants: young people with first episode psychosis; not all participants had a SUD Intervention: vocational intervention (supported employment), not a SUD intervention
Lozano 2013	Allocation: not randomised.
Magura 2003	Allocation: not a randomised trial.
Mangrum 2006	Allocation: randomised. Participants: co‐occurring severe and persistent mental illness and substance use disorders. Interventions: integrated versus parallel treatment. Outcomes: no usable data (not broken down by site, only 2 of 3 sites were randomly assigned).
Martino 2000	Allocation: randomised. Participants: people with psychotic or mood disorders and concurrent DSM‐IV substance‐related disorders. Interventions: pre‐admission motivational interview versus standard pre‐admission interview. Outcomes: no usable data.
Martino 2006	Allocation: randomised. Participants: dually diagnosed psychotic and drug‐related disordered patients. Interventions: pre‐admission motivational interview versus standard preadmission interview. Outcomes: no usable data.
McGurk 2009	Allocation: randomised. Intervention: cognitive remediation, not a SUD focused intervention.
Mercer 1997	Allocation: not randomised.
Mueser 2001	Allocation: not a randomised trial.
Mueser 2009	Allocation: randomised. Participants: family members of patients with a dual diagnosis. Interventioin: family education programme, did not directly involve patients.
NCT00043693	Allocation: randomised. Participants: family members of patients with a dual diagnosis. Intervention: family education programme, did not directly involve patients.
NCT00316303	Allocation: randomised. Participants: patients with psychosis and substance use disorder. Intervention: focused on reducing harm (HIV, other risk behaviours); not specific for reducing substance use.
NCT00447720	Allocation: randomised. Intervention: educational programme for case managers.
NCT00495911	Allocation: randomised. Participants: people with first‐episode psychosis;SUD was not listed as an inclusion criteria.
NCT01361698	Allocation: randomised. Participants: substance use not an inclusion criteria. Intervention: recovery focused (increased adherence); not specifically focused on SUD.
NCT02264327	Allocation: randomised. Participants: not patient focused. Intervention: training MI to staff in increasing MI knowledge and skill retention over time
Noordraven 2017	Allocation: randomised. Intervention: financial incentives for improving adherence; not a psychosocial intervention to reduce substance use
Nuijten 2012	Allocation: randomised. Participants: inpatients and outpatients with serious mental illness and SUD. Interventioin: integrated treatment based on hospital status; inpatient or outpatient. No TAU group.
Nuttbrock 1998	Allocation: quasi‐randomised (treatment facilities retained the final acceptance).
Odom 2005	No useable data. Email from author confirmed results not published, supervisor left
Penn 2000	Allocation: quasi‐randomised (alternate allocation).
Petersen 2006	Allocation: randomised. Participants: first‐episode schizophrenia spectrum disorder; not all patients had substance use or dependence (146 vs 401 patients). Interventioin: enriched assertive community treatment vs standard care.
Petrakis 2005	Allocation: randomised. Participants: patients with an Axis I psychiatric disorder and comorbid alcohol dependence. Interventions: naltrexone versus disulphiram; not psychosocial.
Ries 2004	Allocation: randomised. This single‐centre, two‐armed, community‐based RCT was conduced in the USA. Participants: 41 people with severe mental illness Intervention: 1) Contingency Management of supplementary social security income or food voucher with a motivational message, or 2) treatment as usual. Outcome: data were not reported per group for loss to treatment and no means, SD or sample sizes were reported for number of weeks of substance use. The trial was excluded due to a lack of usable data.
Rosenheck 1998	Allocation: randomised. Participants: high users of inpatient services. Interventions: intensive psychiatric community care; no specific substance misuse treatment programme.
Rowe 2007	Allocation: randomised. Participants: only 38% had a psychotic disorder and 30% did not a dual diagnosis.
Sacks 2004	Allocation: randomised. Participants: only 63% of sample had a serious mental illness and no data provided separately for this group.
Sacks 2008	Allocation: randomised. Participants: majority of participants were diagnosed with major depression (65%) with other co‐morbidities (PTSD or anxiety) and history of alcohol or substance use. 27% had bipolar disorder and no mention of other psychotic disorders.
Sacks 2011	Allocation: randomised. Participants: diagnosed with HIV/AIDS and co‐occurring mental and SUD.High percentage of homelessness, incarceration and IV drug use. Intervention: aftercare focused to improve health status focusing on AIDS issues and adhere to AIDS medication. Not a psychosocial intervention to reduce substance use.
Santa Ana 2007	Allocation: not a randomised trial, based on consecutive admissions.
Schmitz 2002	Allocation: randomised. Participants: bipolar disorder exclusively; excluded due to none having a diagnosis of schizophrenia.
Shorey 2015	Allocation: randomised. Participants: veterans with a primary alcohol use disorder, the majority did not have a psychotic disorder.
Sigmon 2000	Allocation: not randomised.
Sitharthan 1999	Participants: study was discontinued, no participants were recruited.
Smeerdijk 2012	Allocation: randomised. Participants: carers of people with a dual diagnosis. Interventioin: MI for family carers, no direct contact with patients.
Smelson 2007	Allocation: randomised. Intervention: designed to facilitate outpatient engagement, not psychosocial intervention to reduce substance use.
Somers 2015	Allocation: randomised. Participants: homeless mentally ill adults, not all had a SUD, Intervention: housing support was provided based on need, intervention was not SUD focused.
Stain 2016	Allocation: randomised, single‐blind trial Participants: young people with ultra‐high risk of developing psychosis; not all patients had a current or past drug or alcohol use problem.
Steadman 2005	Allocation: not randomised.
Swanson 2000	Allocation: randomised. Participants: people with psychotic or major mood disorders and history of hospital recidivism (50% substance misuse). Interventions: involuntary out‐patient commitment. No specific substance misuse treatment.
Tantirangsee 2015	Allocation: randomised. Participants: not all participants had a drug or alcohol substance use disorder. Intervention: to reduce tobacco smoking.
Teague 1995	Allocation: not a randomised trial.
Thornicroft 2007	Allocation: randomised. Participants: case managers of people with a dual diagnosis. Intervention: did not include direct patient contact.
Timko 2004	Allocation: quasi‐randomised (not all patients randomly allocated to community treatment were placed there).
Tyrer 2011	Allocation: randomised. Participants: people with comorbid substance misuse and psychosis. Interventions: nidotherapy is not a specific SUD focused intervention; nidotherapy was developed mainly for people with personality disorders.
Weiss 2000	Allocation: not randomised (sequential allocation).
Weiss 2007	Allocation: randomised. Participants: bipolar disorder exclusively; excluded due to none having a diagnosis of schizophrenia.
Weiss 2009	Allocation: randomised. Participants: bipolar disorder exclusively; excluded due to none having a diagnosis of schizophrenia.
Woolderink 2015	Intervention: evaluation of E‐mental health intervention for children of parents with a mental illness unrelated to SUD

AUDIT: Alcohol Use Disorders Identification Test; CBT: cognitive behavioural therapy; IV: intravenous; DSM‐IV: Diagnostic & Statistical Manual of Mental Disorders 4^th edition; MI: motivational interviewing; PTSD: post‐traumatic stress disorder; RCT: randomised controlled trial; SD: standard deviation; SUD: substance use disorder; TAU: treatment as usual.