Abstract: We include 70 studies involving a total of 4761 participants in the review. The first primary outcome for this review was reduction in the severity of PTSD symptoms, using a standardised measure rated by a clinician. For this outcome, individual TFCBT and EMDR were more effective than waitlist/usual care (standardised mean difference (SMD) -1.62; 95% CI -2.03 to -1.21; 28 studies; n = 1256 and SMD -1.17; 95% CI -2.04 to -0.30; 6 studies; n = 183 respectively). There was no statistically significant difference between individual TFCBT, EMDR and Stress Management (SM) immediately post-treatment although there was some evidence that individual TFCBT and EMDR were superior to non-TFCBT at follow-up, and that individual TFCBT, EMDR and non-TFCBT were more effective than other therapies. Non-TFCBT was more effective than waitlist/usual care and other therapies. Other therapies were superior to waitlist/usual care control as was group TFCBT. There was some evidence of greater drop-out (the second primary outcome for this review) in active treatment groups. Many of the studies were rated as being at 'high' or 'unclear' risk of bias in multiple domains, and there was considerable unexplained heterogeneity; in addition, we assessed the quality of the evidence for each comparison as very low. As such, the findings of this review should be interpreted with caution. The evidence for each of the comparisons made in this review was assessed as very low quality. This evidence showed that individual TFCBT and EMDR did better than waitlist/usual care in reducing clinician-assessed PTSD symptoms. There was evidence that individual TFCBT, EMDR and non-TFCBT are equally effective immediately post-treatment in the treatment of PTSD. There was some evidence that TFCBT and EMDR are superior to non-TFCBT between one to four months following treatment, and also that individual TFCBT, EMDR and non-TFCBT are more effective than other therapies. There was evidence of greater drop-out in active treatment groups. Although a substantial number of studies were included in the review, the conclusions are compromised by methodological issues evident in some. Sample sizes were small, and it is apparent that many of the studies were underpowered. There were limited follow-up data, which compromises conclusions regarding the long-term effects of psychological treatment.

Plain-language summary: This review draws together up-to-date evidence from 70 studies including a total of 4761 people. There is continued support for the efficacy of individual TFCBT, EMDR, non-TFCBT and group TFCBT in the treatment of chronic PTSD in adults. Other non-trauma-focused psychological therapies did not reduce PTSD symptoms as significantly. There was evidence that individual TFCBT, EMDR and non-TFCBT are equally effective immediately post-treatment in the treatment of PTSD. There was some evidence that TFCBT and EMDR are superior to non-TFCBT between one to four months following treatment, and also that individual TFCBT, EMDR and non-TFCBT are more effective than other therapies. No specific conflicts of interest were identified. Although we included a substantial number of studies in this review, each only included small numbers of people and some were poorly designed. We assessed the overall quality of the studies as very low and so the findings of this review should be interpreted with caution. There is insufficient evidence to show whether or not psychological therapy is harmful.