Longitudinal clusters of long-term trajectories in patients with early-onset chronic depression: Two years of naturalistic follow-up after extensive psychological treatment

Abstract

Introduction: In randomized trials, mostly group-level treatment effects of repeated cross-sectional measures are analyzed. However, substantial heterogeneity regarding individual symptom profiles and variability of treatment effects are often neglected, particularly over the long-term course.Objective: Ratings of depression severity over 104 weeks of follow-up after yearlong acute and continuation treatment with the Cognitive Behavioral Analysis System of Psychotherapy (CBASP) or Supportive Psychotherapy (SP) were investigated to cluster intraindividual trajectories and identify risk and protective factors. Methods: Longitudinal cluster analysis and multinomial logistic regression analysis were conducted to group intraindividual long-term trajectories from one of the largest psychotherapy trials in early-onset chronic depression.Results: Two-year post-treatment trajectories of N=176 patients with early-onset chronic depression were clustered into four groups. Only 16.5% of patients remitted (Cluster 1), while the majority continued to experience subthreshold (35.8% Cluster 2) or major depressive symptoms (47.7% Cluster 3-4). Patients previously treated with the CBASP had a 45% lower risk of experiencing major depressive symptoms (Cluster 3) than patients in the SP group (RR=0.55, 95% CI=0.31 to 0.97, p=.03). Further treatment in the health care system during follow-up, especially psychological outpatient treatment, reduced depression severity. Comorbid disorders or childhood emotional/physical abuse had detrimental effects.Conclusion: Despite significant effects in favor of acute treatment with CBASP compared to SP, the majority of patients experienced subthreshold or major depressive symptoms over two years of follow-up. This calls for a long-term perspective with innovative treatment approaches such as the sequential model or modular psychotherapy.