Aurelie Lange

152 | Appendices In Chapter 6 it was investigated how alliance and adherence develop during treatment and how this development is uniquely and jointly related to treatment outcomes up to 18-months post-treatment. For this purpose, a variable-centered (latent growth curve modeling) and a person-centered approach (latent class growth analysis) were used. A total of 848 adolescents and their caregivers having participated in MST were included. Outcomes were assessed at the end of the treatment and at 18-months post-treatment using the scale ‘rule-breaking behavior’ of the Child Behavior Checklist (CBCL) and two MST Ultimate Outcomes (i.e., police contact and out-of-home placement). Alliance and adherence showed an increasing and then flattening slope. We identified two trajectory classes for alliance and three classes for adherence, which were mainly characterized by different initial levels of alliance and adherence. Both alliance and adherence predicted treatment outcomes at the end of treatment, but not at 18 months post-treatment. The effects of alliance could not be replicated using the person-centered approach. In Chapter 7 we summarize and discuss the findings from these five studies. In the first place, we conclude that the Dutch TAM-R is reliable and does predict post-treatment outcome. Nevertheless, the Dutch adherence scores are affected by external sources (Aim 1), such as cultural response tendencies and the amount of experience a therapist or a country has with MST. This suggests that both bias, as well as true differences, may explain the observed lower adherence scores in the Netherlands compared to the US. We further conclude that alliance and adherence can reinforce one another, and that adherence is important for good outcomes (Aim 2). Yet, there needs to be a balance between adherence and adaptability. Treatment outcomes may improve if evidence-based interventions can be adapted to the unique needs of the new setting or individual client, but only if the core elements are retained. It is, therefore, essential to identify which elements of an intervention should be delivered in all situations, and which may be suitable for adaptation to new settings or may be flexibly used by clinicians.