Preventing Suicide With Safe Alternatives for Teens and Youths (SAFETY)

Defined as number of completed assessments at end of intervention (week 12)

Defined as number of completed assessments 3 months after end of intervention

Defined as number of completed assessments 12 months after end of intervention

The fraction of potential participants will be determined as the number of eligible persons compared to the number of randomized persons.

Compliance will be defined as number of completed sessions.

The CEQ is a 6-item measure of treatment credibility and expectancy. Scale points ranges from 0-9 and 0-100%, where a higher score indicates a better outcome.

The CSQ-8 is an 8-item self-rated 4-point scale, measuring different aspects of satisfaction with treatment, e.g. perception of quality of treatment, if the treatment adequately addressed their needs and overall satisfaction. Total range is 8 to 32, with higher values indicating higher satisfaction. Mean in total satisfaction scores on the CSQ-8 for each treatment group at end of treatment will be reported.

Participants are asked to report and rate the discomfort of the eventual adverse events caused by their participation in the treatment.

The C-SSRS is a 22-item measure assessing the frequency and severity of suicidal ideation, suicidal behaviors, and self-harm. The C-SSRS will be administered as a clinical interview at baseline (week 0).

See description above (outcome 9). The C-SSRS will be administered as a self-rated measure for weekly assessments during treatment.

See description above (outcome 9), The C-SSRS will be administered as a clinical interview.

See description above (outcome 9), The C-SSRS will be administered as a clinical interview.

See description above (outcome 9), The C-SSRS will be administered as a clinical interview.

The DERS is a measure of difficulties in emotion regulation, with 36 items rated on a 1-5 Likert scale, with a higher score indicating greater difficulties with emotion regulation.

DERS-16 is a brief 16-item version of the DERS, see description above, with 16 items rated on a 1-5 Likert scale, with a higher score indicating greater difficulties with emotion regulation.

The CERQ is a measure of cognitive emotion regulation, with 36 items on a Likert scale ranging from 1-5. A higher score indicates greater difficulties with cognitive emotion regulation.

The BERQ is a measure of behavioral emotion regulation, with 20 items on a Likert scale ranging from 1-5. A higher score indicates greater difficulties with behavioral emotion regulation.

The EBQ is a measure of emotion beliefs, with 16 items on a Likert scale ranging from 1-7. A higher score indicates more maladaptive beliefs about emotions.

The PAQ is a measure of how emotions are perceived and experienced, with 24 items on a Likert scale ranging from 1-7. A higher score indicates greater difficulties related to alexithymia.

The MSPSS is a measure of perceived social support, with 12 items on a Likert scale ranging from 1-7. A higher score indicates higher level of perceived social support.

The SCORE-15 is a measure of family function, with 15 items on a Likert scale ranging from 1-5. A higher score indicates greater family function.

The DSHI-Y is a 7-item measure assessing occurrence, method, frequency of deliberate self-harm. A higher score indicates higher frequency and severity of self-harm. The DSHI-Y will be administered as a clinical interview at baseline, post and follow-up, and as a self-rated measure for weekly assessments.

The RCADS-S, a shortened version of the Spence Child Anxiety Scale, is a child self-report measure of anxiety- and depression-related psychopathology. Total range is 0-45, Likert scale ranging from 0-3, with higher values representing a worse outcome.

The BHS is a measure of hopelessness, with 20 dichotomous "true/false" items. A higher score indicates greater difficulties related to hopelessness.

The PCM - 1 item version is a measure of expressed emotion, consisting of one question on a Likert scale ranging from 0-10, about how critical an emotionally important individual is perceived to be by the rater.

The BSL-Supplement is a 11-item measure of self-destructive behaviors. Higher score indicates higher frequency of self-destructive behaviors.

The DBT-WCCL is a measure of use of DBT skills use and dysfunctional ways of coping with emotions. Higher average score in the skills use subscale and lower average scores in the dysfunctional coping subscales indicate greater functional coping.

CRAFFT is a 9-item screening measure of alcohol and substance use. A higher score indicates greater difficulties related to substance use.

The PSQI is a 18-item measure of sleep problems. A higher score indicates greater sleep problems.

The CCNES-A is a measure of parental coping responses in response to adolescents' negative emotions. The CCNES-A version used in this trial consists of nine hypothetical scenarios accompanied by six types of responses, rated on a Likert scale ranging from 1-7.

The PHQ-9 is a measure of depression, with 10 items on a Likert scale ranging from 0-3. Higher score indicates greater depressive symptoms.

The GAD-7 is a measure of anxiety, with 7 items on a Likert scale ranging from 0-3. Higher score indicates greater anxiety symptoms.

WSAS-Y is a measure of impaired functioning in school, everyday life, friends and social life, recreation and hobbies and family and close relationships. The scale generates a global score ranging from 0 to 40, with higher scores indicating greater impairment.

The TIC-P is a 37 item measure assessing healthcare and societal resource use, including for example items on healthcare resource use, medications, school absenteeism, and parental productivity loss. In the present trial no health economic evaluations will be conducted. Rather this instrument is included to gain feasibility data in preparation of a planned larger randomized controlled trial. Therefore, no data on TiC-P will be reported in this trial.

The CHU-9D is a measure of health related quality of life, with 9 items on a Likert scale ranging from 1-5. A higher score indicates greater health-related quality of life.

The CGAS is a single item clinician rated 1-100 scale that integrates psychological, social, and academic functioning in children as a measure of psychiatric disturbance. Higher values represent a better outcome.

The CGI-S and CGI-I are clinician rated 1-item scales ranging from 1-7 where higher ratings indicate greater symptom severity (CGI-S), and greater symptom improvement (CGI-I), respectively.