67 Assessing medical decision-making competence in transgender minors 4 Reference standard Of each IC video, three MDC judgements were performed: two by experts and one by the clinician involved in the diagnostic trajectory. These judgements were used for establishing the reference standard. MacArthur Competence Assessment Tool for Treatment (MacCAT-T) Each MacCAT-T video was also judged by three different experts, who rated the subscale scores, total score, and their MDC judgement. These assessments were used for the MacCAT-T-based judgements. The experts received the videos in random order, blinded to other judgements or adolescents’ characteristics. Statistical analyses All statistical analyses were performed by using SPSS, version 26 (IBM Corporation, 2019). Both for the reference standard and MacCAT-T-based judgements, MDC was considered present when at least two out of three judgements were positive (Hein et al., 2015d). The proportion of adolescents assessed positive onMDCwas described as a rawpercentage. The correlation between the reference standard and MacCAT-T-based judgements, as a measure of intermethod agreement, was also described as a raw percentage. Interrater agreement of the three reference standard and three MacCAT-T-based judgements, which is the overall percentage of mean fractions of agreement between the three raters, were calculated as raw percentages. To discern potential associations between MacCAT-T total-scale scores and our main variables of interest (age, intelligence, CBCL total-problem T-score, and duration of the diagnostic trajectory), demographic characteristics were identified as relevant control variables (e.g., gender, family situation, and clinic location) as a first step. Second, multiple linear regression was used to identify variables correlated to the MacCAT-T total scores with pairwise deletion of missing variables.