Trajectories of Treatment Change among Patients with Major Depressive Disorder: Predictors and Associations with Outcomes

Previous research has revealed heterogeneity in outcome trajectories among individuals seeking psychotherapy. However, questions remain as to the number, nature, and predictors of these trajectories. Therefore, the present study had three aims: 1) to identify heterogeneous latent groups among treatment trajectories of 212 clients with major depressive disorder (MDD) seeking psychotherapy at a community mental health training clinic; 2) to identify significant associations between clinical and demographic variables and group membership; and 3) to identify correlations between trajectory shape and positive treatment outcome. Prior to treatment, participants provided demographic information and completed symptom severity ratings. Once in treatment, participants completed a self-report of distress via the Outcome Questionnaire (OQ-45) at every session. Growth mixture modeling was utilized to identify distinct patient subgroups based on outcome trajectories among the sample. Three distinct latent classes of treatment trajectory were identified, providing evidence of heterogeneity in treatment trajectories among individuals with MDD. Baseline distress, pre-treatment work problems, and sleep difficulties were found to be predictive of an individual's membership in a specific trajectory group. Finally, specific shapes of change, namely early response and sudden gains, were associated with positive treatment outcome. Findings from this study can be used to identify patients at risk for treatment failure, allowing clinicians to intervene earlier to enhance mid-treatment feedback and prognosis