Lewis 2002.

Methods	Allocation: randomised Blinding: assessor blind Location: 11 mental health units serving 3 geographically defined catchment areas, Manchester/Salford, Liverpool, and north Nortinghamshire Length of follow‐up: 18 months
Participants	Diagnosis: schizophrenia, schizophreniform disorder, schizoaffective disorder or delusional disorder (DSM‐IV) N = 203* Sex: 141 M, 62 F Age: median ˜ 27 years Included: length of illness: not reported; either first or second admission (within 2 years of a first admission) to inpatient or day patient unit for treatment of psychosis; positive psychotic symptoms for 4 weeks or more; score of 4 or more (moderate or severe) on the PANSS target item either for delusions (Pl) or hallucinations (P3); neither substance misuse nor organic disorder judged to be the major cause of psychotic symptoms Excluded: not reported
Interventions	1. CBT group**: N = 101 Content: The CBT was manual‐based with four stages: Stage 1: a cognitive–behavioural analysis of how symptoms might relate to cognitions, behaviour, and coping strategies. Education about the nature and treatment of psychosis, using a stress vulnerability model to link biological and psychological mechanisms, was used to help engagement. Stage 2: A problem list was generated collaboratively with the participant. This was then prioritised according to the degree of distress attached, feasibility and, where relevant, clinical risk involved. Prioritised problems were assessed in detail and a formulation was agreed which included such issues as trigger situations and cognitions. Stage 3: Interventions particularly addressed positive psychotic symptoms of delusions and hallucinations, generating alternative hypotheses for abnormal beliefs and hallucinations, identifying precipitating and alleviating factors, and reducing associated distress. Stage 4: Monitoring positive psychotic symptoms of delusions and hallucinations. Delivered by:one of five therapists trained in CBT in psychosis, supervised by experienced cognitive therapists. Freqency: 15 ‐ 20 hours within a 5‐week treatment envelope, plus 'booster' sessions at a further 2 weeks and 1, 2, and 3 months Treatment duration: 70 days 2. Standard care group: N = 102 Content: There was no attempt to standardise 'routine care'. This means that the content of 'routine care' was not specifiable, except that it always included day or inpatient treatment and included antipsychotic drugs Delivered by: not reported Frequency: not reported Treatment duration: 70 days
Outcomes	Global state: relapse, rehospitalisation Mental state: general, positive symptoms, negative symptoms, affective symptoms (PANSS scores); delusions (PsyRATs scores) Adverse effects: death of any cause Satisfaction with treatment: leaving the study early Unable to use: Mental state: hallucination ‐ not able to use as data only derived from a subgroup of population) Mental state: (BIS, RSES scores) ‐ data for each group not reported Functioning: social (SFS scores) ‐ data for each group not reported Engagement with treatment: compliance with medication ‐ data for each group not reported Substance misuse ‐ not a predefined outcome for this review
Notes	*This is a triple‐arm study, and 305 participants were included in this study, six people excluded after randomisation. We did not use data from the participants in the supportive therapy arm (n = 106). **Participants in the CBT group also received the standard care intervention.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "Independent, concealed randomisation of individuals with minimisation was then performed by a trial administrator at each centre." (p.s92) Comments: Randomisation was well conducted.
Allocation concealment (selection bias)	Low risk	Quote: "Independent, concealed randomisation of individuals with minimisation was then performed by a trial administrator at each centre." (p.s92) Comments: Participants and investigators enrolling participants could not foresee assignment.
Blinding of participants and personnel (performance bias) All outcomes	High risk	Quote: "The interventions were carried out independently of clinical staff, who were kept unaware of treatment allocation." "Clinical staff were instructed not to divulge details of therapist contacts to the raters." (p.s92) Comments: As the CBT was based on standard care, participants and personnel were not likely to be blinded.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Quote: "All outcome assessments were made blind to treatment allocation. Extensive steps were taken to maintain blindness of raters." (p.s92) Comments: The outcome assessor could not foresee assignment.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Comments: Intention‐to‐treat analysis was conducted.
Selective reporting (reporting bias)	High risk	Comments: The author did not report data for four outcomes.
Other bias	Low risk	Comments: none obvious