Unified Protocol for Children: A Randomized Controlled Trial for the Portuguese Population

Measured with an adaptation of Clinical Global Impression (CGI). The CGI is composed by a severity of illness scale and a scale evaluating changes from the initiation of treatment. Higher scores are indicative of higher severity of psychopathology and lower improvement from the initiation of treatment.

Measured by Child Anxiety Life Interference Scale - self-report (CALIS-C) and parent's report (CALIS-P). The child form is composed by a single scale and the parent form is composed by two subscales (Child Interference Subscale and Family Interference Subscale). Higher scores are indicative of greater interference of anxiety symptoms in the life of the children and the family.

Measured by The Avoidance and Fusion Questionnaire - Youth (AFQ-Y). AFQ-Y assess children's psychological inflexibility, namely children's experiential avoidance and cognitive fusion. Higher scores are indicative of higher levels of children's psychological inflexibility.

Measured by Child- and Parent-Report Measures of Behavioral Avoidance Related to Childhood Anxiety Disorders (CAMS and CAMP). Higher scores are indicative of higher levels of children's behavioral avoidance.

Measured by Positive and Negative Affect for Children (PANAS-C). PANAS-C is composed by two independent subscales: Positive Affect and Negative Affect. Higher scores are indicative of higher levels of children's positive and negative affect, respectively.

Measured by School-Age Temperament Inventory (SATI). It is composed by five dimensions: negative emotionality, inhibition, adaptability, activity, and persistence. Only the subscale of negative emotionality is used in this study. Higher scores are indicative of higher levels of negative emotionality.

Measured by Children's Anxiety Sensitivity Inventory-Revised (CASI-R). Higher scores are indicative of higher levels of anxiety sensitivity.

Measured by Distress Tolerance Scale (DTS). Higher scores are indicative of lower levels of tolerance to feel negative emotions.

Measured by The Child and Adolescent Mindfulness Measure (CAMM). Higher scores are indicative of higher levels of children's mindfulness skills.

Measured by Children's Negative Cognitive Error Questionnaire (CNCEQ). It assesses four types of cognitive errors derived theoretically: catastrophizing, overgeneralization, personalizing, and selective abstraction. CNCEQ yields a Total Score for each type of cognitive error, a Total Score for areas of content (social, academic, Atlético) and a Total Score for cognitive errors. Higher values correspond to more cognitive errors.

Measured by Emotional Expression Scale for Children (EESC). Higher scores are indicative of higher levels of difficulties in children's emotional expression and emotion awareness.

Measured by Hospital Anxiety and Depression Scale (HADS). Higher scores are indicative of higher levels of anxiety and depression.

Measured by Parental anxiety and overprotection scale (PAOS). Higher scores are indicative of higher levels of parental anxiety, parental overprotection and parental support of children's coping behaviors.

Measured by NEO Five-Factor Inventory (NEO-FFI). It assesses the five traits of personality defined in the Five Factor Theory of Personality: Openness, Conscientiousness, Extraversion, Agreeableness and Neuroticism. In the present study only Neuroticism subscale was used. Higher scores are indicative of higher levels of neuroticism.

Measured by Parenting Styles & Dimensions Questionnaire. Only the permissiveness subscale was used with higher scores being indicative of higher levels of parental inconsistency and permissiveness.

Measured by EMBU-P (egna minnen beträffande uppfostran). It assesses four dimensions: emotional support, rejection, control attempt and sibling preference. In this study, only the rejection subscale was used, which assesses parental rejection and criticism. Higher scores indicate higher levels of rejection and parental criticism.

Measured by The Parent Emotion Regulation Scale (PERS). It assesses four dimensions: parents' orientation to the child's emotions, parents' avoidance of the child's emotions, parents' lack of emotional control and parents' acceptance of the child's and their own emotions. In the present study only parents' lack of emotional control scale was used. This subscale assesses the lack of ability to modulate their own negative emotions in the presence of the child. Higher scores are indicative of higher levels of shaping of negative emotions.

Measured by Interpersonal Mindfulness in Parenting Scale (IMP). Higher scores are indicative of higher levels of mindfulness in parenting.

Measured through the number of completers and users that dropped out from the intervention before completing it and through the involvement of the participants in the homework (through a record made at each session).

Measured through specific questions (developed by the researchers) to assess acceptability of the program and to assess satisfaction for each session and for the global intervention - for parents and children; Measured by Parent Motivation Inventory - PMI (to measure parent motivation to participate in treatment).