Table 1.

Description of assessment instruments of the Choose Change study

Abbreviation	Description
CEQ	The Credibility and Expectancy Questionnaire [50] is a 6-item scale for measuring treatment expectancy and rationale credibility for use in clinical outcome studies. There are two rating scales, one from 1 to 9 and another (Item 4) from 0 to 100%.
AAQ-II	The Acceptance and Action Questionnaire [51] is a 10-item self-report measure of psychological flexibility and acceptance. Each item is rated on a 7-point scale from 1 (never true) to 7 (always true).
PF	The PsyFlex [42] is a self-developed 6-item self-report measuring the process of Psychological Flexibility. Each item is rated on a 5-point scale from 1 (very often) to 5 (very rarely).
BAT	The Behavioral Avoidance Test: Radiant Heat Induction Test [52]. Thermal testing is performed by applying a thermode on the patient’s skin. A patient’s response to temperature stimuli (the sensory thermal threshold) is recorded.
OSS-3	The Oslo Social Support Scale [53] is a 3-item self-report measure of social support. Item 1 is rated on a 4-point scale, items 2 and 3 are assessed on a 5-point scale.
SIS	The Social Interaction Scale is a self-designed 3-item self-report measuring the frequency, duration, and discomfort of social interactions in the last 24 h. Item one is rated on a 4-point scale, item 2 on a 3-point scale.
RAS	The Relationship Assessment Scale [54] is a 7-item self-report measure of relationship satisfaction. Each item is rated on a 7-point scale from 1 (low satisfaction) to 5 (high satisfaction). Items 4 and 7 are reverse scored.
SNQAS	The Social Network Quality and Action Scale is a self-developed 10-item scale measuring the relationship quality with important people in a person’s life. In item 1, up to 15 people can be listed, Items 2–10 are assessed individually for every person mentioned in item 1. Items 2 and 3 specify the relation with the person concerned. Of the following items, 4 are rated on a 7-point scale, 2 on a 5-point scale and 1 on a 4-point scale.
CFQ	The Cognitive Fusion Questionnaire [55] is a 7 item self-report measure of cognitive fusion. Each item is assessed on a 7-point scale from 1 (never true) to 7 (always true).
FFMQ-SF	The Five Facet Mindfulness Questionnaire – Short Form [56] is a 24-item self-report measure of different aspects of mindfulness. Each item is measured on a 5-point scale from 1 (never applies) to 5 (always applies).
VLQ	The Valued Living Questionnaire [57] is a 2-item self-report measure assessing valued living in 12 different life domains. Both items are assessed on a 10-point scale from 1 (not important) to 10 (very important).
WHODAS 2	The World Health Organization Disability Assessment Schedule – 2 [58] is a 17-item self-report disability assessment with 7 domain-specific scores. Each item is rated on a 5-point scale from 1(no difficulty) to 5 (extreme difficulty or cannot do).
MHC-SF	The Mental Health Continuum – Short Form [59] is a 14-item self-report measure of emotional, social and psychological well-being. Each item is rated on a 6-point scale from 0 (never) to 5 (every day)
MLQ	The Meaning in Life Questionnaire [60] is a 10-item measure of meaning in life. Each item is assessed on a 7-point scale from 1 (absolutely untrue) to 7 (absolutely true).
DERS	The Difficulties in Emotion Regulation Scale [61] is a 36-item self-report measure of emotion dysregulation. Each item is rated on a 5-point scale from 1 (almost never) to 5 (almost always).
ASQ	The Affective Style Questionnaire [62] is a 20-item self-report measure of individual differences in emotion regulation. Each item is rated on a 5-point scale from 1 (not true of me at all) to 5 (extremely true of me).
SCID-I/Screener	The Structured Clinical Interview for DSM-IV – Axis I disorders [38] is a semi-structured interview guide that enables mental health professionals to make DSM-IV Axis I diagnoses.
Severity Scale	The Anxiety Disorders Interview Schedule (ADIS) severity rating scale [39] was utilized to rate the diagnoses on a scale from 0 (absent) to 8 (very severe)
BDI-SF	The Beck Depression Inventory – Short Form [63] is a 7-item self-report measuring severity of symptoms associated with depression. Each item is rated on a 4-point scale.
BSCL	The Brief Symptom Checklist [64] is a 53-item self-report measure. Each item is rated on a 5-point scale from 0 (not at all) to 4 (very strongly).
PSWQ	The Penn State Worry Questionnaire [65] is a 16-item self-report assessing the trait of worry. Each item is rated on a 5-point scale from 1 (not a tall typical of me) to 5 (very typical of me).
FQ	The Fear Questionnaire [66] is a 24-item self-report of phobia. Each item is rated on a scale from 0 to 8.
OCI-R	The Obsessive-Compulsive Inventory – Revised [67] is an 18-item self-report measure of obsessive-compulsive symptoms. Each item is rated on a point scale from 0 (not at all) to 4 (extremely).
SIAS	The Social Interaction Anxiety Scale [68] is a 20-item self-report measure of fears in general social interaction. Each item is rated on a 5-point scale from 0 (not at all) to 4 (extremely).
PSS	The Perceived Stress Scale [69] is a 14-item self-report measure of perceived stress in different situations. Each item is rated on a 5-point scale from 0 (never) to 4 (very often).
DSS	The Daily Stress Scale [70] is a 7-item self-report measure of perceived stress in different life domains. Each item is rated on a 7-point scale from 1 (little incriminating) to 7 (not affected)
DAP-PS	The Developmental Assets Profile – Prosocial Subscale [71] is an 8-item self-report measure of developmental assets linked to different indicators of well-being. Each item is rated on a 4-point scale from 1 (not at all or rarely) to 4 (extremely or almost always)
EVOS	The Prosociality questionnaire is a self-designed 9-item self-report asking about prosociality in partnerships and derived from prosocial principles [72]. Items 1, 6, 7, and 9 are rated on a 5-point scale. Items 2–5, and Item 8 are rated on a 3-point scale.
COOP	The Cooperation Scale [73] is a 13-item self-report measure of cooperation in social situations. Each item is rated on a 6-point scale from 1 (I don’t agree at all) to 6 (I totally agree).
SRAS	The Self Report Altruism Scale [74] is a 20-item self-report measure of altruistic behavior. Each item is rated on a 5-point scale from 1 (never) to 5 (very often).

Note. Full names of the instruments are printed in bold for a better overview