62 Chapter 4 widely between countries (Hein et al., 2012; Stultiëns, Dierickx, Nys, Goffin, & Borry, 2007). Research reveals that minors who have not yet reached the legally set age for MDC often have the mental capacity to understand the implications of a decision (Hein et al., 2014). In contrast, minors may differ from adults by not yet having developed stable long-term goals in life and basing their decisions on values that might change (Cohen & Cohen, 1996). Additionally, minors are not as likely as adults to consider the benefits and risks associated with a decision (Halpern-Felsher & Cauffman, 2001). In our study, to deal with discrepancies between local laws and international jurisdictions, we focused on adolescents’ decisionmaking competence or capacity for giving consent regarding the decision to start treatment with PS, regardless of the legal age to give IC (alone or together with their parents). In the context of our study, legally, parents have to give consent when the child is aged <12 years; between the ages of 12 and 15 years, parents and child both have to give consent; and at age ≥16 years, the child is allowed to give consent independently. MDC describes the capacities needed for making an autonomous medical decision (Grisso, Appelbaum, & Hill-Fotouhi, 1997). To reach MDC, a person needs to fulfil four criteria: (1) understand the information relevant to one’s condition and the proposed treatment; (2) appreciate the nature of one’s circumstances, including one’s current medical situation and the underlying values; (3) reason about benefits and potential risks of the options; and (4) be able to express a choice (Appelbaum & Grisso, 1988). MDC is relative to a specific task and context. It is one of the three prerequisites for giving a valid IC, next to being well-informed and without coercion (Beauchamp & Childress, 2008; Grisso & Appelbaum, 1995). In paediatric daily practice, MDC is generally assessed implicitly and in an unstructured way, which may lead to inconsistencies (Appelbaum, 2007). A study in which researchers reviewed 23 existing measures reveals that the MacArthur Competence Assessment Tool for Treatment (MacCAT-T) has the most empirical support for assessing MDC (Dunn, Nowrangi, Palmer, Jeste, & Saks, 2006; Grisso et al., 1997; Kim, Caine, Currier, Leibovici, & Ryan, 2001; Kim et al., 2007). The MacCAT-T proved reliable in assessing mental competence in adult patients with dementia, schizophrenia, and other psychiatric conditions (Cairns et al., 2005; Owen et al., 2008; Palmer et al., 2005). The cognitive, emotional, and social abilities of minors develop over time and so do their decision-making capacities (Hein et al., 2012). Age is often considered to be the best determinant for assessing MDC (Dorn, Susman, & Fletcher, 1995). Some research reveals that 12 years is a common age to reach MDC (Billick, Burgert 3rd, Friberg, Downer, & BruniSolhkhah, 2001). Other research reveals that minors <12 years of age may be capable of