Are psychological interventions for adult PTSD more efficacious and acceptable when treatment is delivered in higher frequency? A meta-analysis of randomized controlled trials.

Background: Two systematic reviews indicated that higher treatment frequency of psychological interventions for adult PTSD may lead to higher efficacy and less dropout. Yet, a quantitative review is missing.

Methods: We conducted a thorough systematic literature search and included trials meeting the following criteria: a) random allocation, 2) PTSD was primary treatment focus, 3) ≥ 70% interview-based PTSD rate 4) mean age ≥ 18 years, and 5) N ≥ 20. Treatment session frequency was analyzed dichotomously (< 1.5 vs. ≥ 1.5 sessions/week) and continuously (sessions per week & minutes per week).

Results: A total of 160 RCTs with data from 10,556 patients were included. Analyses yielded similar treatment efficacy irrespective of treatment frequency definitions and whether differential efficacy was estimated directly via head-to-head trials or indirectly via comparisons to the same comparison group. Intense (≥ 1.5 sessions/week) vs. standard (< 1.5 sessions/week) delivery was, however, associated with significantly lower dropout rates (as a proxy for acceptability) for trauma-focused interventions (18.64% vs 11.54%, respectively, p = .024), but not for non-trauma-focused interventions.

Conclusions: We found no evidence for differential treatment efficacy of intense vs. standard psychotherapies for adult PTSD. Evidence for increased acceptability was found for intense vs. standard trauma-focused interventions.