66 Chapter 4 Medical decision-making competence The MacCAT-T is a quantitative, semistructured interview used to assess the four MDC criteria and takes 15 to 20 minutes (Grisso et al., 1997; Appelbaum & Grisso, 1988). In this study, the Dutch version modified for children and adolescents was used (Hein et al., 2015c). In the current study, the disclosure of information was adapted to treatment with PS for transgender adolescents (Grisso et al.,1997; Hein et al., 2012; Hein et al., 2015d). Examples of interview-questions are “what would be possible consequences if you would choose to undergo this intervention, and what if you would not?”. The tool provides a total score and subscale scores for each of the four MDC criteria. An overall cut-off score for MDC is not provided. The assessor weighs the subscale scores, along with contextual information (e.g., substantial risks of treatment, far-reaching consequences, and whether there is support of caregivers), and judges MDC in each individual case. Recent research revealed that the four MDC criteria constitute a continuum or single trait in children (Hein et al., 2014). Full-scale intelligence quotient The full-scale intelligence quotient (IQ) was assessed by the Dutch Wechsler Intelligence Scale for Children in adolescents aged ≤16 years and by the Dutch Wechsler Adult Intelligence Scale in adolescents aged >16 years (Wechsler, 1997; Wechsler, 2005). Child Behaviour Checklist The parent-reported Child Behaviour Checklist (CBCL) was used to assess behavioural and emotional difficulties (Achenbach & Rescorla, 2001; Verhulst & van der Ende, 2013). The total-problem T-score was calculated as age standardized measure of total behavioural and emotional difficulties. Procedures Both gender identity clinics that participate in the study follow the Standards of Care and the Endocrine Society clinical practice guideline (Coleman et al., 2012; Hembree et al., 2017). The diagnostic trajectory, which is spread over a longer period of time, concludes with a session for signing a printed IC statement by adolescents and parents. This standard IC session was videotaped and used to establish the reference standard for MDC in this study (see below), similar to previous studies.16,35 After the IC session, the MacCAT-T interview was administered by one of the researchers, which was also videotaped, to provide the MacCAT-T-based judgements of MDC. A panel of 12 experts (including child psychiatrists, paediatric endocrinologists, child psychologists, and master thesis medical students) was trained in judging MDC on the basis of the four criteria, which are currently considered the generally accepted reference standard (Carney, Neugroschl, Morrison, Marin, & Siu, 2001; Etchells et al., 1999; Hein et al., 2014; Kim et al., 2001).