Improving patient outcomes will be enhanced by understanding “what works, for whom?” enabling better matching of patients to available treatments. However, answering this “what works, for whom?” question requires sample sizes that exceed those of most individual trials. Conventional methods for combining data across trials, including aggregate-data meta-analysis, suffer from key limitations including difficulty accounting for differences across trials (e.g., comparing “apples to oranges”). Causally interpretable meta-analysis (CI-MA) addresses these limitations by pairing individual-participant-data (IPD) across trials using advancements in transportability methods to extend causal inferences to clinical “target” populations of interest. Combining IPD across trials also requires careful acquisition and harmonization of data, a challenging process for which practical guidance is not well-described in the literature.

We describe methods and work to date for a large harmonization project in pediatric obsessive-compulsive disorder (OCD) that employs CI-MA.

We review the data acquisition, harmonization, meta-data coding, and IPD analysis processes for Project Harmony, a study that (1) harmonizes 28 randomized controlled trials, along with target data from a clinical sample of treatment-seeking youth ages 4–20 with OCD, and (2) applies CI-MA to examine “what works, for whom?” We also detail dissemination strategies and partner involvement planned throughout the project to enhance the future clinical utility of CI-MA findings. Data harmonization took approximately 125 hours per trial (3,000 hours total), which was considerably higher than preliminary projections.

Applying CI-MA to harmonize data has the potential to answer “what works for whom?” in pediatric OCD.

Despite evidence for its efficacy, exposure therapy for anxiety is rarely used in routine care settings. Efforts to address one major barrier to its use – therapists’ negative beliefs about exposure – have included therapist-level implementation strategies, such as training and consultation. Experiential training, in which therapists themselves undergo exposures, has recently demonstrated feasibility, acceptability and preliminary effectiveness for increasing exposure use.

This study aimed to assess: (1) therapists’ perceptions of experiential training and (2) barriers and facilitators to implementing exposure following training.

Therapists who underwent experiential training (n=12) completed qualitative interviews and quantitative questionnaires. Interviews were coded using an integrated approach, combining both inductive and deductive approaches. Mixed methods analyses examined how themes varied by practice setting (community mental health versus private practice) and exposure use.

Results highlight how therapist-level factors, such as clinician self-efficacy, interact with inner- and outer-setting factors. Participants reported positive perceptions of exposure after training; they noted that directly addressing myths about exposure and experiencing exposures themselves improved their attitudes toward exposure. Consistent with prior literature, issues such as insufficient supervisory support, organizational constraints, and client characteristics made it challenging to implement exposures.

Results highlight the benefits of experiential training, while also highlighting the need to consider contextual determinants. Differences in responses across practice settings highlight areas for intervention and the importance of tailoring implementation strategies. Barriers that were specific to therapists who did not use exposure (e.g. hesitancy about its appropriateness for most clients) point to directions for future implementation efforts.