Art program, a manualized Art group delivered in a social format, has been designed for children on the Autism Spectrum delivered by health professionals with experience of running social groups for Autistic children. The Art program's participants (4-8 participants) meet face to face weekly for 16 weeks for 75 minutes.

The parents (parent proxy) will fill this questionnaire. The NEQ is a 32-item questionnaire requiring adolescents to quantify, on 5-point Likert scale with response options ranging from "Not at all" to "Extremely", any negative events experienced during the intervention period, asking participants to attribute their causality to either the program or external circumstances

The children will fill this questionnaire. This is a 9-dimension Health related quality of life scale (worried, sad, pain, tired, annoyed, school work, sleep, daily routines and activities), designed to estimate the adolescent's Quality adjusted life years (QALY), providing a standardized measure of disease burden. The measure is rated on a 5-point scale with a "don't" sentence linked with no problems (e.g. I don't feel sad today) and "very" with the participant experiencing a lot of problems (e.g. I feel very sad). Calculation of an universal score is supported by an adolescent specific scoring algorithm, with 1 representing 'full health' and 0 'death'.

The parents will fill this questionnaire (Parent form). This will be measured via a tailored version of the Trimbos/iMTA questionnaire for patients with a psychiatric disorder (TiC-P), a well-established questionnaire examining health care usage as well as any work, education and productivity losses incurred by participants and their carers. The modified version of the TIC-P employed in this study comprise six sections enquiring about health care visits, support received

- Page 4 of 6 [DRAFT] both at and outside of school, medications and supplements, work, and education and productivity losses incurred by both parents and children.

The children and parents both will fill this questionnaire. This is a short 6-item parent and adolescents self-report instrument, measuring satisfaction with group attendance. Each item is scored on a 4-point Likert scale with response options ranging from "Yes, very much" to "No" with an open comment section, encouraging participants to freely share their experiences with the intervention.

This measure will be used as the parent's primary outcome.The Social Responsiveness Scale - Second Edition (SRS-2) School-Age Form is a 65-item rating scale, designed to measure social deficits in individuals with ASD via parent proxy report has been used as the primary outcome in a previous study evaluating KONTAKT and has been used as the basis for the power calculation for the present RCT. The SRS-2 (2014) enables calculation of a universal score and five treatment subscales: social awareness, social cognition, social communication, social motivation, and restricted interests and repetitive behaviour. These subscales are designed to align closely with the DSM-5 criteria for ASD. The scale takes approximately 15 to 20 minutes to complete with items scored on a 4-point Likert-type scale, ranging from "not true (0)" to "almost always true (3)". The expected value for individuals with a primary diagnosis of ASD is approximately 100.

evaluates the impact of a disability and its context on an individual's functioning. For the purpose of this study only item related to the KONTAKT© objectives (social communication and interaction) will be selected from the Autism Core set after the manual has been translated to English.

2.4. This parent-report and child self-report is derived from the International classification of functioning's autism coreset that identifies the personality traits of young children aged 6-16 under 5. Responses are dichotomous (True or False).

is a weekly measure specifically designed for this study to evaluate the motivation to participate in the groups (both intervention and control) and will be assessed through a 2-item child and parent self-report and a parents proxy-report text, asking "On a scale of 1-5 (as demonstrated by emoji) how much did you like attending this week's group?" and "On a scale of 1-5 (as demonstrated by emoji) how interested are you in attending the next session?" To check for reliability, the results from this measure will be attached to the participants' attendance in the groups.

the LERID friendship questionnaire is a 46-item self-report measure of children's perceptions of the quality of their relationship with their best friend around 11 different aspects of friendship experience: commitment, security, satisfaction, intimacy, protection from victimization, help, affection received from the friend, trust of the friend, trust received from the friend, comfort, Validation and Authenticity of the friendship. The measure is rated on a 5-point Likert scale from "Not true" (1) to "Really true" (5).

Social Interaction Anxiety Scale (SIAS) is self-report used mainly with adults. The measure has been used with adolescents participating in the KONTAKT program. This study will only use the items which became significant in that study. The measure is scored on a 5-point Likert scale from "Not at all (0)" to "Extremely (4)". The higher scores on the scale indicate higher social interaction anxiety experienced.