Distinctive Trajectory Groups of Mental Health Functioning among Assertive Community Treatment Clients: An Application of Growth Mixture Modelling Analysis

Abstract

Objective: Assertive community treatment (ACT) studies that have used conventional, statistical growth modelling methods have not examined different trajectories of outcomes or covariates that could influence different trajectories, even though heterogeneity in outcomes has been established in other research on severe mental illness. The purpose of our study was to examine the general trend in mental health functioning of ACT clients over a 2-year follow-up time period, to discover groups of ACT clients with distinctive longitudinal trajectories of mental health functioning, and to examine if some of the key sociodemographic and illness-related factors influence group membership. Method: A 2-year, prospective, within-subjects study of 216 ACT clients within southern Ontario, collected functional outcome data at baseline and 12 and 24 months using the Colorado Client Assessment Record. Baseline covariates included sex, primary diagnosis, number of comorbidities, hospitalization history, and duration of illness. Growth mixture modelling (GMM) was used to examine trajectories. Results: Clinical staff assessments of ACT clients showed a statistically significant improvement in functioning and 84% achieved successful community tenure. GMM analysis identified 2 classes of ACT clients: class 1 (79.63% of clients) experienced lower and stable overall functioning, and class 2 (20.37%) showed a better baseline functioning score and improvement in the overall functioning over time. Class membership was predicted by the number of comorbidities and diagnosis. Conclusions: Our study suggests general stability in overall functioning for the sampled ACT clients over 2 years, but significant heterogeneity in trajectories of functioning.