Project Summary FM is a chronic pain condition characterized by widespread musculoskeletal pain, tenderness and stiffness associated with fatigue and sleep disturbance. The goal of reducing opioid use in patients with chronic pain requires that proven non-pharmacological treatments are applied in clinical practice. We have recently completed the FAST (Fibromyalgia Activity Study with TENS) trial demonstrating efficacy of Active TENS compared with Placebo TENS or No Treatment in women with fibromyalgia (FM). FAST was the first study to conclusively demonstrate efficacy of TENS in musculoskeletal pain. While physical therapists are trained in the use of TENS, it is underused in clinical practice. This application proposes to conduct an embedded pragmatic trial to compare effectiveness of physical therapy with or without the addition of TENS for FM patients within physical therapy (PT) practices as the study sites. The overall goal of this proposal is to (1) demonstrate the feasibility of adding TENS to treatment of patients with FM in a real-world PT practice setting and (2) to determine if addition of TENS to PT reduces pain, increases adherence to PT and allows patients with FM to reach their specific functional goals with less drug use. We hypothesize that using TENS in a PT setting is feasible and that FM patients using TENS are more likely to reach their therapeutic goals and reduce medication use. To test these hypotheses, we will utilize the following specific aims planning (UG3) and implementation (UH3) phases. UG3 Aim 1: Recruit physical therapy practices as research sites for this embedded pragmatic clinical trial and understand usual practice for patients with FM to inform trial processes. UG3 Aim 2: Ensure adequacy of infrastructure at potential study sites to complete a PT embedded pragmatic trial. UH3 Aim 1: Assess the feasibility of using TENS in addition to physical therapy for treatment of patients with FM using a cluster-randomized pragmatic clinical trial of routine PT (as selected by the therapist on an individual basis) with or without TENS. UH3 Aim 2: Determine if TENS use improves the symptoms of FM, increases adherence to physical therapy, increases the likelihood of meeting therapeutic goals, and reduces medication use. This study will address the critical need to develop a strategy for implementing effective non- pharmacologic treatments for FM. Our multi-disciplinary research team will leverage their experience from a recently completed randomized controlled trial and an implementation study for TENS in primary care practice to complete a real-world trial of TENS for FM in a PT setting. Successful completion of this trial will provide generalizable effectiveness data for referring providers, physical therapists, and insurers and will inform future pragmatic trials of non- pharmacologic treatments conducted in PT practices.