Evaluation of Radically Open Dialectical Behavior Therapy for Youth At Risk for Developing Severe and Enduring Eating Disorders

Change in eating disorder symptoms measured with Eating disorder Examination Questionnaire (EDE-Q)

EDE-Q is a 28-item self-report questionnaire, designed to assess the range, frequency and severity of behaviors associated with an eating disorder. It is categorized into four sub-scales: Restraint, Eating Concern, Shape Concern and Weight Concern, and an overall global score. The score is obtained by calculating the mean for the total score and the subscales respectively (min = 0, max =6), higher scores indicate more severe eating disorder symptoms.

Change in eating disorder symptoms measured with Eating disorder symptom list (EDSL)

The EDSL is an eight-item self-rating questionnaire designed to assess eating disorder symptoms important for diagnosis. The scale is developed to detect change, or lack of change, during treatment. Participants are asked how many days during the preceding week they: restricted the amount of food, restricted the type of food, binged, vomited, used laxatives/diuretics, exercised excessively, experienced fear of gaining weight, or had thoughts about weight and shape that affected their self-image. Responses are given on an eight-point Likert scale ranging from 0 (no days) to 7 (seven days). Higher scores indicate greater difficulties

Change in body mass index (BMI)

Weight and height will be combined to report BMI in kg/m\^2, assessed with a valid and reliable device in a standardized procedure. BMI is only an outcome for those with an underweight before study start, defined as 85% of expected body weight in relation to the participants age and gender.

Feasibility - treatment credibility and expectancy

The Credibility/Expectancy Questionnaire (CEQ) is a psychological assessment tool designed to measure participants' expectations of treatment effects and their perceptions of the credibility of a psychological intervention. The CEQ helps researchers understand how expectations may influence treatment outcomes. The scale consists of six items, four of them are recorded using a nine-point Likert scale, ranging from 1 (not at all) to 9 (very much), higher scores indicate a greater credibility/expectation. The scale also contains two items asking for a percentage rating of how great improvement they think/feel will happen.

Change in Eating disorder related functional impairment measured with the Clinical Impairment Assessment questionnaire (CIA)

The CIA is a 16-item self-report measure of the severity of psychosocial impairment due to eating disorder features, Each item is rated on a four-point Likert scale ranging from 'Not at all' to 'A lot'. The minimun score is zero and the maximum score is 48, with higher scores indicating a more severe impairment.

Change in functional impairment measured with Uppsala scale of Functional Impairment in Daily life (UFID)

The UFID is a Five-item, five-point Likert scale that measures functional impairment in daily life on a score between 1-5. Higher scores indicate more functional impairment.

Change in self-perceived health measured with EQ-VAS

The EQ-VAS is a visual analogue scale that takes values between 100 (best imaginable health) and 0 (worst imaginable health), on which patients provide a global assessment of their health.

Change in maladaptive overcontrol, expressive suppression, measured with Emotion regulation questionnaire (ERQ)

The ERQ is a self-rating instrument designed to assess individual differences in the use of emotion regulation strategies. It is composed of ten items divided into two factors: cognitive reappraisal and expressive suppression. Participants indicate their answers on a 7-point Likert-scale ranging from 1 (total disagreement) to 7 (total agreement).

The occurrence of Adverse events

Adverse events, primarily defined as worsening of mental health symptoms, weight loss, increased self-harming or suicidal behaviors, or any other unwanted experiences related to the intervention, will be assessed in a checklist by the individual therapist.

Adherence to treatment protocol (ratings by therapists) assessed with the adherence form

Therapist adherence to the treatment protocol will be measured by therapist ratings for each session. The adherence form will contain a checklist of the session structure where the therapist is instructed to check the boxes of which parts were included, in addition to an own evaluation of treatment adherence, rated on a scale from 1 (=low adherence), 2 (=acceptable adherence), and 3 (=good adherence) A higher score indicate better adherence. The adherence form also include a space to write down the main theme/themes of the session content.