Peer support during in vivo exposure homework increases likelihood of prolonged exposure therapy completion.

Exposure-based treatments such as prolonged exposure therapy (PE) are effective for veterans with PTSD. However, dropout rates as high as 50% are common. The Department of Veterans Affairs employs peers to increase mental health treatment engagement, however peers are not routinely used to help patients complete PE homework assignments. The present study included 109 veterans who decided to drop out from exposure-based treatment after completing seven or fewer sessions and used a randomized controlled design to compare PE treatment completion rates in response to 2 forms of peer support: (1) standard weekly telephone-based peer support vs. (2) peer-assisted in vivo exposure, wherein peers accompanied veterans (virtually or in person) during a limited number of in vivo exposure assignments. There were no differences between instrumental vs general peer support conditions as randomized. However, post hoc analyses indicated that 87% of those who completed at least one peer-assisted in vivo exposure completed treatment, compared to 56% of those not completing any peer-assisted in vivo exposure. The dose effect of peer-assisted in vivo exposure increased to 93% with 2 or more peer-assisted exposures, and 97% with 3 or more peer-assisted exposures. The present study suggests that augmenting PE with instrumental peer support during in vivo exposure homework may reduce dropout if completed. Future research should test whether the impact of peer-assisted in vivo exposure is enhanced when offered at the beginning of treatment as opposed to waiting until the point of dropout.