The goal of this clinical trial is to learn if Massed Prolonged Exposure Therapy (M-PE) can improve PTSD symptoms and reduce substance use in adults receiving intensive outpatient (IOP) treatment for substance use disorder (SUD). The main questions it aims to answer are:

• Does M-PE reduce PTSD symptoms more effectively than trauma treatment as usual (TAU)?
• Does M-PE reduce the number of days participants use substances?
• How do patient-centered outcomes (such as depression, suicidal thoughts, and quality of life) differ between M-PE and trauma TAU?
• Researchers will compare M-PE to treatment as usual to see if M-PE leads to better mental health and substance use outcomes and lower dropout rates.

Participants will:

• Attend multiple therapy sessions per week (M-PE) or receive usual care
• Complete assessments at baseline, during treatment, end-of-treatment, 1-month, 3-month, and 6-month follow-up
• Share feedback through surveys and interviews about their experience in the program

Posttraumatic stress disorder (PTSD) and substance use disorder (SUD) often co-occur. PTSD+SUD comorbidity is associated with more severe PTSD, worse treatment outcomes for substance use, greater suicide risk and worse functioning than having one of these disorders. First-line treatments for PTSD, particularly Prolonged Exposure Therapy (PE), are effective in treating PTSD among those with a SUD. While PE is one of the most effective treatment options for PTSD among those with PTSD+SUD, effects are smaller and dropout is higher than among people with PTSD without a SUD. A promising way to enhance outcomes is to offer PE in a massed format (M-PE; i.e., multiple sessions per week instead of once weekly).

M-PE has been shown to be effective in improving PTSD symptoms and substantially reducing dropout in outpatient care. Preliminary findings suggest M-PE delivered concurrent to intensive SUD programming is a promising strategy that warrants further study. Evaluating the effectiveness of M-PE delivery in of SUD IOP program in improving PTSD and other mental health outcomes is the necessary next step in this critical research.

The mixed-method two-group Hybrid Type I effectiveness-implementation randomized clinical trial (RCT) aims to determine the effectiveness of M-PE delivery in SUD IOP in reducing dropout rates and improving outcomes as compared to trauma treatment as usual (TAU).

The specific aims are to 1) Compare the effectiveness of M-PE to trauma TAU in IOP SUD treatment in impacting PTSD symptoms and Percent days use of primary substance; 2) Explore differences in treatment arms on patient-centered outcomes, including: a) days use of other (non-primary) substances, b) depressive symptoms, c) functioning, c) quality of life (QoL), e) suicidal ideation, and f) participant satisfaction; 3) Examine gender as a moderator and changes in trauma-related cognitions, cravings, and their temporal association as mediators of change in PTSD and substance use; and 4) Conduct a mixed-method process evaluation to understand patients', providers', and clinical stakeholders' experiences with M-PE, explore barriers and facilitators to integrating M-PE into IOP SUD treatment, and identify strategies for widespread implementation.

Participants will include 168 male and female patients with any trauma type who are participating in IOP SUD program at Gateway Community Services, Inc. Assessments will occur at baseline, and will continue for the duration of treatment, at end-of-treatment, 1-month posttreatment, 3-months posttreatment, and 6-months posttreatment. We will conduct a mixed-method, multi-stakeholder process evaluation with patients, providers, and clinical leaders.

Inclusion Criteria:

• Age 18+
• Enrolled in SUD treatment at Gateway Community Services
• Meet DSM-5 criteria for a SUD (Tobacco Use Disorder alone not sufficient for inclusion)
• Meet DSM-5 criteria for PTSD
• Able to give informed consent

Exclusion Criteria:

• severe cognitive impairment
• current suicidal or homicidal intent requiring immediate treatment
• current unstable psychotic or manic symptoms not attributable to SUD

We plan to share individual participant data (IPD) that underlie the results reported in the study, following de-identification and in compliance with IRB and data use agreements. A data dictionary will also be provided to allow for accurate interpretation of variables and data structure. Data will be made available to qualified researchers upon request, following approval of a data use agreement and verification of appropriate data security measures.

The IPD and supporting information will be available beginning 6 months after publication of the primary outcomes and will remain available for 5 years.

Qualified researchers affiliated with academic institutions or research organizations will be able to request access to the de-identified individual participant data (IPD) and accompanying materials, including the data dictionary and study protocol. Access will include data related to primary and secondary outcomes, as well as adverse events, once appropriate data use agreements are in place.

Requests must be submitted to the study team and will be reviewed for scientific merit, ethical use, and compliance with institutional and regulatory guidelines. Approved users will be granted access through a secure data-sharing platform or via direct encrypted transfer, in accordance with Rutgers University and sponsor policies on data security and privacy.