Online-delivered eye movement desensitization and reprocessing treatment for adults with post-traumatic stress disorder due to multiple traumas: a non-concurrent multiple baseline design.
Background: No controlled studies incorporating randomization have been conducted to investigate the effectiveness of online eye movement desensitization and reprocessing (EMDR) treatment, despite its use in clinical practice.Objective: This study evaluated the effect of online EMDR treatment in adults aged 18-65 years with post-traumatic stress disorder (PTSD) resulting from multiple traumas.Method: A multiple baseline single-case experimental design (n = 21) was employed. Participants were patients with PTSD due to multiple traumas, recruited from a mental healthcare institution in the Netherlands. They were randomly assigned to baseline phases of 2, 3.5, or 5.5 weeks. After this, participants received 10 weekly online EMDR sessions. The primary outcome was the total score on an adapted version of the PTSD Checklist for DSM-5 (PCL-5), which was administered twice a week during baseline and intervention phases, and once 12 weeks after the end of the intervention phase. We performed visual analysis and calculated the improvement rate difference (IRD) for each individual separately to determine whether online EMDR was effective. We also performed a paired t-test and calculated Cohen's d for pretreatment and post-treatment comparisons, and pretreatment versus follow-up to evaluate effects at the group level.Results: Visual analysis and IRD scores showed that the treatment was effective for 15 participants, with effect sizes ranging from small to very large. The mean scores on the PCL-5 at group level decreased significantly over time between pretreatment and post-treatment (Mdiff = 23.6, Cohen's d = 1.34, 95% CI 0.74-1.93), as well as between pretreatment and follow-up (Mdiff = 27.2, Cohen's d = 1.62, 95% CI 0.95-2.27).Conclusion: Most participants showed a reduction in symptoms following the start of the online EMDR. Furthermore, at the group level there was a significant and clinically relevant reduction in symptoms over time. This provides preliminary evidence for the effectiveness of online EMDR treatment.