Empowering Pain Psychology Access and Collaboration (EPPAC) to Improve Treatment Engagement Among Medicaid-insured Adults With Chronic Low Back Pain: a Pilot Randomized Controlled Trial

Chronic low back pain (cLBP) is among the leading causes of disability worldwide, affecting approximately 12.8 million adults in the United States. Individuals with low socioeconomic status (SES) are disproportionately affected, with roughly twice the rate of developing cLBP compared with higher-SES populations. The investigator's prior work has shown that socioeconomically disadvantaged adults with cLBP report worse pain-related outcomes than more advantaged counterparts, underscoring the need for effective and accessible treatments in this population.

Clinical practice guidelines recommend nonpharmacological approaches, including pain psychology, as first-line treatments for cLBP. Among the most established pain psychology treatments is cognitive behavioral therapy (CBT), which targets maladaptive patterns of thinking and behavior that contribute to pain, disability, and distress. A growing evidence base also supports emotional awareness and expression therapy (EAET), presented to participants in REACH as Pain and Emotion Reprocessing Therapy (PERT). EAET is grounded in contemporary pain neuroscience and addresses emotional experiences, stress, and interpersonal processes that may contribute to chronic pain.

Despite the availability of these treatments, a substantial proportion of participants referred for pain psychology do not initiate treatment, with reported initiation rates ranging from 24% to 73%. Preliminary findings from the OPTIMIZE trial, a pragmatic comparative effectiveness study of nonpharmacological treatments for cLBP conducted across three US health systems, indicate that only 59% of participants randomized to CBT initiated treatment, with socioeconomic factors such as neighborhood deprivation emerging as significant predictors of non-initiation. These findings suggest that socioeconomically disadvantaged participants face distinct barriers to engaging with psychological treatments for pain, and that simply offering effective treatments is insufficient if participants do not start treatments.

Participant engagement strategies have shown promise in improving treatment uptake. Shared decision-making (SDM) supports informed choices by presenting treatment options alongside benefits and trade-offs in a structured, collaborative conversation. Motivational interviewing (MI) supports motivation by exploring ambivalence and strengthening commitment in a non-confrontational manner. A prior trial by the investigator's team demonstrated that a single-session MI intervention delivered during a clinical encounter increased participation in physical therapy, reduced disability, and improved health outcomes among adults undergoing surgery for degenerative lumbar spinal stenosis. More recently, the Equity Using Interventions for Pain and Depression (EQUIPD) pilot trial demonstrated that coaching paired with a decision aid to facilitate SDM about nonpharmacological pain treatments was feasible and showed improvements in shared decision-making, participant engagement, and therapeutic alliance among Black participants with chronic musculoskeletal pain. However, no study has examined whether integrating SDM and MI into a pain psychology evaluation can improve treatment initiation among socioeconomically disadvantaged participants, nor has any study offered participants a structured choice between CBT and EAET.

To address this gap, the Empowering Pain Psychology Access and Collaboration (EPPAC) intervention, a brief, psychologist-led engagement strategy designed to be embedded within a standard pain psychology evaluation, was developed. EPPAC combines MI techniques with a structured SDM framework to help participants understand how psychology relates to pain, explore whether treatment fits the participant's situation, and choose between CBT and EAET based on the participant's values and preferences. In participant-facing REACH materials, EAET is presented as Pain and Emotion Reprocessing Therapy (PERT). The purpose of this study is to evaluate the feasibility, acceptability, and preliminary effectiveness of EPPAC compared with usual care among Medicaid-insured adults with cLBP in a pilot randomized controlled trial.