Study quality and efficacy of psychological interventions for posttraumatic stress disorder: a meta-analysis of randomized controlled trials.

Background: Research indicates that higher study quality may be associated with smaller treatment effects. Yet, knowledge about the association between study quality and treatment efficacy for posttraumatic stress disorder (PTSD) is limited. We aimed at evaluating the efficacy of psychological interventions for adult PTSD and the association between study quality and treatment effects.

Methods: We conducted a systematic search to identify randomized controlled trials (RCTs) that examined the efficacy of psychological interventions for chronic PTSD symptoms in adult samples with at least 70% of patients being diagnosed with PTSD by means of a structured interview. We assessed study quality using the following eight criteria from prior research: ⩾ 50, all patients met criteria for PTSD, a treatment manual was used, therapists were trained, treatment integrity was checked, intent-to-treat analyses were applied, randomization was conducted by an independent party, and treatment outcome was conducted by blind assessors.

Results: The search resulted in 136 RCTs with 8978 patients. Active treatment conditions were largely effective in reducing PTSD symptoms at posttreatment and follow-up (Hedges' = 1.09 and 0.81, respectively) when compared to passive control conditions. The comparison to active control conditions at posttreatment and follow-up resulted in medium effect sizes. A total of 14 trials met all study quality criteria and these trials produced large effect sizes when compared to passive control conditions at posttreatment and follow-up.

Conclusions: Overall, study quality was not significantly associated with effect size. The findings indicate that psychological interventions can effectively reduce PTSD symptoms irrespective of study quality.