Symptom change trajectories in patients with persistent somatic symptoms and their association to long-term treatment outcome

Objective: This study investigated symptom change trajectory for patients with persistent somatic symptoms (PSS) during psychotherapy and the association of these patterns with pre-treatment characteristics and long-term outcome. Methods: Growth mixture modeling was used to identify trajectory curves in a sample of N = 210 outpatients diagnosed with PSS and treated either with conventional cognitive behavioral therapy (CBT) or CBT enriched with emotion regulation training (ENCERT). Results: We identified three subgroups of patients with similar symptom change patterns over the course of treatment (a "no change," "strong response," and "slow change" subgroup). Higher initial anxiety symptoms were significantly associated with the no change and strong response subgroups; symptom-related disability in daily routine with no changes. Patients with a strong response had the highest proportion of reliable improvement at termination and at six-month-follow-up. Conclusion: Our results indicate that, instead of one common change pattern, patients with PSS respond differently to treatment. Due to the high association of symptom curves with long-term outcome, the identification and prediction of an individual's trajectory could provide important information for clinicians to identify non-responding patients that are at risk for failure. Selecting personalized treatment interventions could increase the effectiveness of psychotherapy.