Empowered Relief and Exercise Rehabilitation for People With Subacromial Shoulder Pain

Pain, Expectations, Beliefs and Behaviour: Untying the Knot to Guide Care

The goal of this clinical trial is to learn whether a single 2-hour online pain skills session called Empowered Relief can help adults with subacromial shoulder pain who are taking part in a 12-week exercise program.

The main questions it aims to answer are:

• Does Empowered Relief lower unhelpful thoughts and beliefs about pain?
• Does Empowered Relief help participants complete more of their prescribed exercises?

All participants will receive the same 12-week exercise program and the Empowered Relief session. The timing of the Empowered Relief session will be randomly assigned between day 10 and day 26 after starting the exercise program. This allows researchers to compare each participant's responses before and after the session.

Participants will:

• Follow a 12-week home exercise program for their shoulder.
• Take part in one 2-hour online Empowered Relief session.
• Answer brief daily questions for 12 weeks about their thoughts about pain, what they expect to feel during exercise, what they actually feel after exercise, and how much of their exercise program they complete.
• Answer brief weekly questions after their Empowered Relief session about their use of the strategies taught in the session.
• Complete longer questionnaires at the start of the study and after 4, 8, and 12 weeks.

This study uses a multiple-baseline single-case experimental design (SCED) across participants to investigate the effects and mechanisms of a brief pain skills intervention in adults with subacromial shoulder pain.

All participants receive a standardized 12-week exercise-based rehabilitation program. The program consists of individually adapted resistance exercises targeting shoulder external rotation, abduction, and flexion. Participants are instructed to exercise daily during the first 8 weeks and every second day during the final 4 weeks.

In addition to the exercise program, all participants receive a single 2-hour online Empowered Relief session. Empowered Relief includes pain education, mindfulness principles, cognitive behavioral skills, and self-regulation strategies. The session is delivered individually by an instructor certified in the standardized Empowered Relief program.

The timing of Empowered Relief is randomly assigned for each participant between day 10 and day 26 after the start of the exercise program. The actual intervention date may vary by up to 2 days from the assigned date. This creates different baseline periods across participants. Each participant serves as their own control, allowing outcomes before the Empowered Relief session to be compared with outcomes after the session.

Participants answer brief questions every day for 12 weeks. The daily outcome measures represent four predefined domains: pain-related beliefs, expected pain responses to exercise, actual pain responses following exercise, and exercise adherence. In the hypothesised causal model, pain-related beliefs, expected pain responses, and actual pain responses are considered hypothesised intermediate domains, while exercise adherence represents the distal outcome domain. All four domains are assessed using primary daily endpoints.

Following the Empowered Relief session, participants also answer brief weekly questions about their use of the strategies taught during the session. These measures are used to describe engagement with Empowered Relief strategies.

Although daily outcomes are collected for 12 weeks, the prespecified primary SCED analyses use repeated within-person observations collected during the first 8 weeks. This period includes observations both before and after Empowered Relief and represents the time frame most closely connected to the intervention.

The study tests two primary direct-effect hypotheses (H1 and H2) and a predefined set of hypothesised indirect-effect pathways (H3-H7). The direct-effect hypotheses examine whether the introduction of Empowered Relief affects pain-related beliefs and exercise adherence. The indirect-effect hypotheses examine temporal pathways linking Empowered Relief to exercise adherence through the hypothesised intermediate domains of pain-related beliefs, expected pain responses, and actual pain responses.

Main direct-effect hypotheses:

H1: Effect of Empowered Relief on Pain Beliefs Introduction of Empowered Relief will produce a clear and immediate positive change in the level and/or trend of pain beliefs relative to baseline for each participant.

H2: Effect of Empowered Relief on Exercise Adherence Introduction of Empowered Relief will produce a clear and immediate positive change in the level and/or trend of exercise adherence relative to baseline for each participant, controlling for relevant covariates.

Main indirect-effect hypotheses:

H3: Empowered Relief → Pain Beliefs → Exercise Adherence Daily changes in pain beliefs following Empowered Relief will be followed by same-day changes in exercise adherence. Reductions in negative pain beliefs are linked to higher levels of exercise adherence, and vice versa.

H4: Empowered Relief → Pain Beliefs → Expected Pain → Exercise Adherence Daily changes in pain beliefs following Empowered Relief will be followed by same-day changes in expected pain responses, followed by same-day changes in exercise adherence. Reductions in negative pain beliefs are linked to more favourable expected pain responses and higher levels of exercise adherence, and vice versa.

H5: Empowered Relief → Pain Beliefs → Expected Pain → Actual Pain → Exercise Adherence Daily changes in pain beliefs following Empowered Relief will be followed by same-day changes in expected pain responses, followed by same-day changes in actual pain responses, followed by next-day changes in exercise adherence. Reductions in negative pain beliefs are linked to more favourable expected and actual pain responses and higher levels of exercise adherence, and vice versa.

H6: Empowered Relief → Pain Beliefs → Actual Pain → Exercise Adherence Daily changes in pain beliefs following Empowered Relief will be followed by same-day changes in actual pain responses, followed by next-day changes in exercise adherence. Reductions in negative pain beliefs are linked to more favourable actual pain responses and higher levels of exercise adherence, and vice versa.

H7: Empowered Relief → Pain Beliefs → Actual Pain → Expected Pain → Exercise Adherence Daily changes in pain beliefs following Empowered Relief will be followed by same-day changes in actual pain responses, followed by next-day changes in expected pain responses, followed by same-day changes in exercise adherence. Reductions in negative pain beliefs are linked to more favourable actual and expected pain responses and higher levels of exercise adherence, and vice versa.

Additional exploratory analyses:

In addition to testing H1-H7, the same daily outcome measures will be used in exploratory analyses of direct effects of Empowered Relief on expected and actual pain responses and to explore additional temporal relationships between the daily outcome domains.

Sample size:

We plan to include a total of 30 participants with sufficient data to be included in the primary analyses. Sufficient data are defined as no more than 20% missing observations across the daily assessments during weeks 1-8, providing a minimum of 45 observations per participant during the time frame most closely connected to the change in phase. Enrolment is planned to continue until 30 participants have provided sufficient data to be included in the primary analyses, and is hence expected to differ from the anticipated number of participants (n=60) described in the Enrolment Section.

Inclusion Criteria:

• Age 18 to 65 years, inclusive.
• Shoulder pain for at least 3 months.
• Sufficient Danish language proficiency to understand study information, follow instructions, and complete questionnaires.
• Diagnosis of subacromial pain syndrome (SAPS), confirmed by either:
• an existing clinical diagnosis provided by a referring clinician, or
• a standardized study-based clinical examination with at least 3 of the following 5 tests positive: Painful Arc test, Empty Can (Jobe's) test, Neer's test, Hawkins-Kennedy test, and External Rotation Resistance test.
• Pain Catastrophizing Scale (PCS) score greater than 16.

Exclusion Criteria:

• Current regular use of strong analgesic medication, excluding over-the-counter medication.
• Pregnancy.
• Referral for postoperative shoulder rehabilitation.
• Corticosteroid injection in the affected shoulder within the past 2 months.
• Current fracture of the affected shoulder, radiographically verified.
• Glenohumeral osteoarthritis in the affected shoulder, radiographically verified.
• History of shoulder dislocation or subluxation in the affected shoulder.
• Suspected labral lesion of the affected shoulder.
• Suspected full-thickness rotator cuff tear.
• Suspected frozen shoulder (adhesive capsulitis).
• Presence of competing conditions that may explain the shoulder pain or interfere with participation, including but not limited to cancer, inflammatory rheumatic disease, neurological disorders, fibromyalgia, or severe psychiatric disease.