Internet-delivered Emotion Regulation Individual Therapy or Adolescents (IERITA) With Self-injury Within Child and Adolescent Mental Health Services

The DSHI-Y measures the frequency of the most common NSSI behaviors. The primary outcome will be the proportion of treatment remission. Remission will be defined as the absence of self-injury the past 30 days. The primary outcome measure will be the clinician-rated DSHI-Y. In cases where clinician ratings are unavailable, the self-rated DSHI-Y will be used.

The DSHI-Y measures the frequency of the most common NSSI behaviors. Change in NSSI frequency from baseline to respective follow-up will be a secondary outcome. The primary outcome measure will be the clinician-rated DSHI-Y. In cases where clinician ratings are unavailable, the self-rated DSHI-Y will be used.

The CGAS measures global functioning on a single item ranging from 1 to 100, with a higher value indicating better functioning. Clinician-rated.

The DERS-16 measures difficulties in emotion regulation. The total score ranges from 16 to 80, with higher scores indicating greater difficulties. Self-rated (adolescent and parent).

The CHU-9D measures health related quality of life. The scale has 9 items with a summary score between 9 and 45, where a higher score indicates greater health-related quality of life. Self-rated (adolescent).

The BSL supplement measures the frequency of self-destructive behaviors. We will measure behaviors of self-harm, suicide attempt, binge eating, self-induced vomiting, high-risk activities, getting drunk, substance use, medication misuse, outbreaks of anger/physical attacks and impulsive/shameful sexual encounters, resulting in a total score between 0 to 40 where a higher score indicates greater frequency of self-destructive behaviors. Self-rated (adolescent).

The RCADS-25 measures symptoms of depression and anxiety in children and adolescents. This version has 25 items with a total score between 0 and 75, with higher scores indicating greater levels of symptoms. Self-rated (adolescent).

The CCNES-A measures parental coping in response to adolescents' negative emotions. The CCNES-A consists of nine hypothetical scenarios accompanied by six types of responses (i.e., emotion focused, problem-focused, minimization, punitive, expressive encouragement, and distress responses). Separate summary scores are calculated per subscale (type of response) and ranges from 1 to 7, with higher scores indicating greater usage of a certain parental coping style. Self-rated (parent and adolescent).

The TIC-P measures healthcare and societal resource use, including for example items on healthcare resource use, medications, school absenteeism, and parental productivity loss. Self-rated (parent).

The IIPAS measures patient adherence to guided internet-delivered behavioral interventions. This scale has 5 items, and a total score ranging from 0 to 20, where 0 indicates no adherence and 20 perfect adherence. Clinician-rated.

Two items asking the participant to rate their own adherence the past week. Self-rated (adolescent).

Two items asking the participant to rate change in treatment credibility from the previous treatment week. Self-rated (adolescent).

CEQ measures treatment credibility and expectancy. This version of the scale has 1 item ranging from 0 to 100, with higher scores indicating greater credibility/expectancy. Self-rated (adolescent).

The CSQ measures satisfaction with treatment. This scale has 8 items and a summary score ranging from 8 to 32, with higher scores indicating greater treatment satisfaction. Self-rated (adolescent and parent).

A scale were participants are asked to report, describe, and rate the discomfort/impact of any negative effects or adverse events caused by their participation in the treatment. Participants rate the impact of potential adverse events when it happened and today on a scale from 1 to 4, where a higher score indicates greater impact. Self-rated (adolescent and parent).

The C-SSRS - 6 item version measures the frequency and severity of suicidal ideation and behaviors. Clinician-rated.

Participants report presence, type, focus, and change an of any potential other concomitant treatment during the trial. Self-rated (adolescent and parent).

Clinicians report time spent on treatment.

Clinicians report number of completed sessions and modules for adolescents and parents.

The DSHI-Y measures the frequency of the most common NSSI behaviors. Self-rated (adolescent).

The DERS-16 measures difficulties in emotion regulation. The total score ranges from 16 to 80, with higher scores indicating greater difficulties. Self-rated (adolescent).

Two items about suicidal behavior from the C-SSRS are used to measure suicidality during treatment. The items concern preparatory behavior and suicide attempts the past seven days. Self-rated (adolescent).

ISAS measures frequency, function, age of onset, experience of, and willingness to stop engaging in self-injury. There are 39 items describing common functions of self-injury. Participants are asked to rate if a certain function applies to them, by marking the statement as "Not relevant", "Partly relevant", or "Very relevant". Self-rated (adolescent).

S-NoMAD measures implementation of interventions from a normalization process theory perspective. The first section in S-NoMAD includes questions about the respondent, the second (2 items) and third (20 items) include questions about the intervention. The items in the second section are answered on a 10-point Likert scale ranging from "Not at all" to "Completely". The items in the third section are answered using a 5-point Likert scale, ranging from "Disagree Strongly" to "Agree Strongly". Participating clinicians answer the S-NoMAD once, after they have treated at least three families with the intervention (i.e., to have some experience of the intervention).

Adolescents will be asked two questions about the format used to report NSSI: (1) "What was your experience of reporting NSSI in the different formats?", and in case where discrepancies occur between the two reporting formars between: (2) "Which frequency rating do you prefer?". Both questions will be administered by an assessor during a single assessment session.

Therapist behaviors are rated separately as 0 (absence of behavior), 1 (inadequate performance), or 2 (competent). Rated by experienced clinical supervisors.

Clinicians report presence or absence of possible treatment adaptions (e.g., changes in therapist contact or what material to focus on).

Participants are asked to rate, using a single item, the perceived benefit of the intervention-specifically, how much of the knowledge gained continues to help them today. Self-rated (adolescent and parent).

Current mental health disorders, age, previous and current treatment. Clinician-rated. Gender and sexual orientation. Self-rated (adolescent). Country of birth, living situation, parental occupation, parental academic degree, and parental history of mental health disorders. Self-report (parent)

Four questions asking participants to rate how frequently they engage in the following activities: eating candy, drinking soda, playing video or computer games, and watching movies. Clinician-rated and self-rated (adolescent)

Registry data from the National Patient Register.

Grades and eligibility in primary school and upper secondary school, and highest education level. Registry data from the Swedish National Agency for Education and the Swedish longitudinal integrated database for health insurance and labour market studies (LISA).

Registered psychiatric disorders. Registry data from the National Patient Register.

Occupation, including unemployment and sick leave. Registry data from the Swedish longitudinal integrated database for health insurance and labour market studies (LISA).

Registry data from the National Cause of Death Register.

Registry data from the National Prescribed Drug Register.

Suicide attempts registered by the health care. Registry data from the National Patient Register and Regional Healthcare Registers.

The RCADS measures symptoms of depression and anxiety in children and adolescents. RCADS has 47 items with a total score between 0 and 141, with higher scores indicating greater levels of symptoms. Registry data from the National Quality Register for Child and Adolescent Mental Health Services (Q-BUP).

The Kidscreen-10 measures quality of life through 10 items. The summary score ranges from 10 to 50 where a higher score indicates greater quality of life. Registry data from the National Quality Register for Child and Adolescent Mental Health Services (Q-BUP).

The CGAS measures global functioning on a single item ranging from 1 to 100, with a higher value indicating better functioning. Registry data from the National Quality Register for Child and Adolescent Mental Health Services (Q-BUP).