A systematic review and meta-analysis of trans-diagnostic third-wave online psychological interventions

Existing meta-analyses on the effect of online psychological interventions (OPIs) have found small to medium effect sizes for the treatment of anxiety and depression. On the other hand, third-generation trans -di-agnostic OPIs are very rare and, due to the large variability among disorders, symptoms or target populations, it is difficult to assess their overall effect. Other systematic reviews and meta-analyses have overly broad inclu-sion criteria that make the understanding of the findings more difficult. The current study aims to analyze the empirical evidence for third-wave trans-diagnostic OPIs designed to decrease symptoms and promote psycholog-ical flexibility, including studies that compare a OPI to some control condition (e. g., waiting list, treatment as usual or other that should distress both at completion and at the last follow-up. On the other hand, duration, age and attrition rate are all mediating variables for the effect on psychological flexibility at the end of treatment. The findings suggest that the high attrition rates observed on tele-psy-chology need to be mitigated; if this is not possible, intention-to-treat approaches should be adopted for data analysis.