Effectiveness of treatment for cannabis use disorder in New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Master of Philosophy in Rehabilitation at Massey University

This study, believed to be the first cannabis treatment outcome study in New Zealand, used a naturalistic design to examine the relationships among client characteristics and correlates of cannabis use problems, treatment variables, outcome measures, and client satisfaction. Participants were 63 persons seeking treatment for cannabis use problems recruited from four geographically diverse outpatient settings. All participants completed baseline assessment and began treatment as typically delivered at New Zealand drug treatment services. A high rate of attrition characterized the study from very early on and continued through follow-up. Eighteen participants completed posttreatment assessment. Outcome measures for those who completed treatment revealed a significant reduction in both cannabis use and psychological distress, accompanied by a significant increase in self-efficacy. A significant correlation between attending more sessions and better outcomes on days of cannabis use and self-efficacy was also noted. However, at treatment termination two-thirds (12) were still using cannabis on at least 3 days per week, with half (9) using daily/near daily. Hypotheses regarding the relationship between theoretically important client variables and treatment dropout were tested. No predictors of dropout were established. Attrition peaked at 86% at the final assessment point with 8 (only) responses to the 3-month follow-up survey. While clients were generally satisfied with treatment services received, some suggestions for improvement to the cannabis treatment programmes were made. Retention- and therapeutic-enhancement strategies are discussed in terms of making treatment services more responsive to identified client needs to improve outcomes. Recommendations for clinical and research attention include the development of individualized treatment packages tailored to meet the presenting needs and deficits of cannabis clients, and ongoing routine evaluation of these programmes