Olivares 2014.

Study characteristics
Methods	Study design: randomised controlled trial Number of study centres and location: 9 high schools in Spain Study setting: schools
Participants	N = 117 (CBT (expert): N = 39; CBT (inexperienced): N = 39; waitlist: N = 39) Mean age (SD): 15.42 (0.97) Age range: 14 to 17 Gender: 61.8% female Inclusion criteria: generalised social phobia (based on ADIS‐C) Exclusion criteria: depression, borderline personality disorder, narcissistic disorder, paranoid disorder, long history of substance abuse, aggressive behaviour, missing 3 consecutive treatment sessions, and have not previously received psychological treatment
Interventions	CBT (expert) Intervention: IAFS (multicomponent programme: Intervention in Adolescents with Social Phobia) Delivery format: child only; group Therapist contact time: 18 hours (12 x 90 minutes) Who delivers the intervention: clinical psychologists (degree in psychology) with more than 2 years' experience treating individual cases and applying psychological treatment to groups with social anxiety CBT (inexperienced) Intervention: IAFS (multicomponent programme: Intervention in Adolescents with Social Phobia) Delivery format: child only; group Therapist contact time: 18 hours (12 x 90 minutes) Who delivers the intervention: psychologists (degree in psychology) with no experience in applying psychological treatment Waitlist/no treatment Intervention: waitlist
Outcomes	Remission of primary anxiety disorder diagnosis post‐treatment: ADIS‐C Reduction in anxiety symptoms (child report) post‐treatment: SAS‐A Reduction in anxiety symptoms (parent report) post‐treatment: SAS‐P
Notes	Anxiety symptoms measures ‐ social anxiety symptoms
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Judgement Comment: No detail given
Allocation concealment (selection bias)	Unclear risk	Judgement Comment: No detail given
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Judgement Comment: Even though blinding was not possible, we judged that it was unlikely this led to a departure from the intended intervention
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Judgement Comment: Evaluators trained, and therapist competence masked, but does not specify if blind to waitlist vs treatment
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Judgement Comment: Attrition given, but only reports completer analyses. No mention of how missing item data were managed
Selective reporting (reporting bias)	Low risk	Judgement Comment: Outcomes reported for all measures
Other source of bias ‐ Therapy integrity	Low risk	Judgement Comment: Fidelity measured
Other bias	Low risk	Judgement Comment: The study appears to be free of other sources of bias