Multisystemic therapy in New Zealand : effectiveness and predictors of outcome : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Psychology at Massey University, Turitea Campus, Palmerston North, New Zealand

Abstract

A one-group pre-test post-test design (including 6- and 12-month follow-up), supplemented with benchmarking analyses, was employed to assess the effectiveness of Multisystemic Therapy (MST) for youth displaying antisocial behaviours in New Zealand. An additional aim of the current study was to assess for predictors and moderators of outcome. The predictor variables assessed included: Client satisfaction, therapeutic and supervisory alliance, therapist and supervisor adherence, therapist and supervisor allegiance, and therapist and supervisor accountability. Seventy-three youth and their families completed the MST program (M = 162 days) and the present study’s measures. Youth and their families experienced improvements in ultimate outcomes (offending frequency, offending seriousness, and days in out-of-home placements) and instrumental outcomes (youth positive and negative behaviour, parent well-being and psychopathology, parent ability, and family functioning) following MST treatment. With a few exceptions, these gains were largely maintained up to 12 months following treatment. Benchmarking analyses indicated that the completion rate and effect sizes were comparable with those from previous MST studies both in New Zealand and the United States. The predictor variables of service satisfaction, therapeutic alliance, and therapist adherence predicted higher levels of change in most instrumental outcomes as expected. However, of significant importance, higher supervisor adherence and supervisory alliances were associated with significantly lower therapist adherence, therapeutic alliance, and some client outcomes. Furthermore, the few significant interactions between predictor variables produced mixed findings, many of which contradicted widely held assumptions. As MST has been demonstrated to be an effective treatment for youth offenders in New Zealand, continuing dissemination and ongoing evaluation of MST in New Zealand is recommended. In particular, given the negative impact of supervision variables on therapist adherence, therapeutic alliance, and some client outcomes, this would include research aimed at assessing various quality control functions of supervision, including supervisor training, mechanisms of supervision related to therapist and client variables, and the potential value of more closely monitoring the process of supervision.