Online Intensive Short-Term Dynamic Psychotherapy for Treatment-Resistant Somatic Symptom Disorder: An Interrupted Time-Series Study.

INTRODUCTION

Somatic symptom disorder (SSD) is associated with substantial impairment and high healthcare use, particularly among patients with chronic symptoms, psychiatric comorbidity, and poor response to standard interventions. Intensive short-term dynamic psychotherapy (ISTDP) is a promising emotion-focused approach, but evidence in treatment-resistant SSD remains limited.

METHODS

In this interrupted time-series study, 25 SSD patients who showed no improvement across two empirically supported online interventions in the preceding project year received up to 16 sessions (M = 14.1) of online ISTDP. Piecewise multilevel modeling compared PHQ-15 trajectories across 60 weeks before and 21 weeks after start of ISTDP. Secondary measures (PHQ-9, GAD-7, PCL-5, DERS-16) were administered pre-, post-, and at 12-week follow-up.

RESULTS

PHQ-15 trajectories were stable or slightly worsening during the pretreatment year but declined significantly after ISTDP began, corresponding to a large estimated slope difference (d = 1.08) at the end of the treatment phase. Among completers (n = 22), 59% achieved minimal clinically meaningful improvement (≥3 PHQ-15 points), 27% showed ≥30% reduction, and 14% met recovery criteria. Secondary outcomes showed significant pre-post improvements in depression (d = 0.68) and anxiety (d = 0.42), while trauma symptoms and emotion regulation showed small, non-significant changes (d ≤ 0.30). Gains were largely maintained at 12-week follow-up. Emotional responses to treatment were common, but serious adverse events rare and dropout low.

CONCLUSIONS

Online ISTDP appears feasible and effective for SSD patients who do not benefit from lower intensity interventions and may represent a useful next step in stepped-care pathways for complex, treatment-resistant presentations.