Trajectories of Change in Psychotherapy

The current study used multilevel growth mixture modeling to ascertain groups of patients who had similar trajectories in their psychological functioning over the course of short-term treatment.

A total of 10,854 clients completed a measure of psychological functioning before each session. Psychological functioning was measured by the Behavioral Health Measure, which is an index of well-being, symptoms, and life-functioning. Clients who attended 5 to 25 sessions at 46 different university/college counseling centers and one community mental health center were included in this study. Client diagnoses and the specific treatment approaches were not known.

A 3-class solution was a good fit to the data. Clients in classes 1 and 3 had moderate severity in their initial psychological functioning scores, and clients in class 2 had more distressed psychological functioning scores. The trajectory for clients in class 1 was typified by early initial change, followed by a plateau, and then another gain in psychological functioning later in treatment. The trajectory for clients in class 2 demonstrated an initial decrease in functioning, followed by a rapid increase, and then a plateau. Last, the clients in class 3 had a steady increase of psychological functioning, in a more linear manner.

The trajectories of change for clients are diverse, and they can ebb and flow more than traditional dose-effect and good-enough level models may suggest.