Table 2.

Overview of study outcome measures

Type of variable	Domain/Concept	Instrument	Items	Source			Assessment
				A	P	T	t 0	t1-t3	t 4	t 5
Primary outcome	Depressive symptoms	CDI-2 (FV) CDI-2 (SV)	28 12	x x			x	x	x	x
Secondary outcome	Depressive symptoms	NRS for core symptoms of depression a	3	x			x	x	x	x
		CDI-2 parent version	17		x		x		x	x
	Depression diagnosis	K-SADS affective disorders		x	x		x		x	x
	Top three problems	TP measurea	3	x			x	x	x	x
	Suicidal ideation (if score 2 on item 8 CDI-2)	VOZZ suicide items	8	x			x	x	x	x
	Health-related quality of life	EQ-5D-Y	6	x	x		x		x	x
Cost-effectiveness	Healthcare costs	Cost diary	21		x		x		x	x
Moderators	Depression severity	K-SADS		x	x		x		x	x
	Comorbidity	BPM	19	x	x		x		x	x
	Demographics adolescent/parent/therapist			x	x	x	x
Mediators	Negative cognitive errors	CNCEQ-R (FV) CNCEQ-R (SV)	16 5	x x			x	x	x	x
	Behavioural activation	BADS (FV) BADS (SV)	25 9	x x			x	x	x	x
	Problem solving skills	SPSI-R	10	x			x	x	x	x
	Relaxation	PSS-10	10	x			x	x	x	x
		NRS for relaxation	1	x			x	x	x	x
Treatment characteristics	Current and previous treatment	VEHI	6	x			x			x
	Expectancy of treatment	PETS	7	x			x
	Therapeutic alliance	TASC-r	12	x		x		x	x
	Groups cohesion	GCQ-s	12	x				x	x
	Cooperation with treatment	CWT	5			x		x	x
	Satisfaction treatment	SSS	3	x					x

Abbreviations: A Adolescent, FV Full-length version, NRS Numerical Rating Scale, P Parents, SV Short version, T Therapist, t₀ Baseline assessment, t_1–3 Intermediate assessments, t₄ Post-assessment, t₅ 6-month follow-up assessment.

^aThese questionnaires will also be administered prior to each session