Problem: The number of patients living with chronic musculoskeletal (MSK) pain has steadily increased over the past decade with costs rising equally. Long-standing pain is associated with significant maladaptive beliefs about pain, psychological characteristics and associated behaviors which involve structural and functional neurobiological characteristics which share common pathophysiological mechanisms as chronic pain. The investigators recent priority setting partnership investigated the research priorities from 1000 patients with chronic MSK pain, relatives, and clinicians. Better pain education was rated as one of the three most important research areas.

Solution: Pain science education has the potential to target maladaptive psychological and behavioral components that may contribute to the maintenance of chronic pain. The KISS project will evaluate the effect of a pain neuroscience education program (PNE4Adults) on rehabilitation outcomes in patients with chronic MSK pain. This intervention has the potential to change beliefs and behaviors surrounding pain in patients with chronic MSK pain. If this is successful in disrupting maladaptive cycles contributing to chronicity, this may improve outcomes for many thousand citizens.

Introduction: Between 20% and 33% of people across the globe live with a painful musculoskeletal (MSK) condition. Costs correspond to almost 2% of the gross domestic products of European countries, posing a challenge for health care systems across the world. Patients with chronic musculoskeletal pain have a high use of healthcare, reduced work ability, loss of productivity, and loss of quality of life. Current care guidelines underline that pain science education (PSE) is a vital part of the care delivered to people suffering from chronic pain. PSE is thought in part to attenuate central sensitization and improve self-efficacy potentially mediated through decreased pain catastrophizing and modulating nocebo-related effects. On a patient level, PSE has been shown to reduce pain catastrophizing, pain intensity, and fear-avoidance in addition to improved physical functioning, self-efficacy, and pain knowledge. Combining exercise and PSE shows greater short-term improvements in pain, disability, kinesiophobia, and pain catastrophizing compared to exercise alone and the RESTORE-trial showed the benefit of adding cognitive components. On a societal level, PSE has further shown to minimize health expenses. However, some of the proposed barriers include training of the therapist delivering the education, access to training material, time during consultation, and patients' health literacy levels. Even in Denmark, a country with a highly educated population, the prevalence of people with inadequate health literacy is high, with nearly 4 out of 10 people facing difficulties accessing, understanding, appraising, and applying health information. This underlines the need to consider novel ways of delivering PSE across all levels of health literacy.

Due to the lack of tools to facilitate PSE programs, the investigators adapted an existing pain science education program that was developed by Pas et al. (2018) (PNE4Kids) to teach children with chronic pain about the underlying biopsychosocial mechanisms contributing to pain. The adapted version, named PNE4Adults, consists of a manual for the therapist and a board game to enhance engagement and participant involvement. It provides the therapist with a clear "how-to" manual and an accessible way for patients to understand the complex concept of pain. This new PSE program may also hold promise for adult patients with low levels of health literacy and enhance learning due to its practical tools and build-in teach-back. The focus on integrating PSE into rehabilitation may enhance the therapeutic alliance needed to facilitate the patients' ability to manage their own symptoms. The investigators feasibility study in adult patients with chronic MSK pain in community-based rehabilitation (Eiger, Rathleff et al. 2024 - under review) showed that PNE4Adults was well accepted (100%) and understandable by all (100%) patients, including those with low levels of health literacy. Qualitive interviews revealed that patients (irrespective of their health literacy) acquired a deeper understanding of their own situation and their pain. This novel approach may reduce the inequality in delivering of pain education.

Purpose of Sub-project 1 The primary aim of the KISS-project is to evaluate the added effect of PSE ('PNE4Adults') to "usual care" compared to "usual care" alone in community-based rehabilitation.

The investigators hypothesis is PSE plus "usual care" will result in a larger improvement of musculoskeletal health (MSK-HQ) after 3 months (primary endpoint) compared to patients undergoing "usual care" in the municipality.

Purpose of Sub-project 2 The secondary aim is to use a process evaluation to understand how it works, and for whom the program works.

The purpose of the process evaluation is to understand how it worked and for whom, and not if it worked. The investigators will combine in-house registrations from the municipality, clinician observations, individual interviews, and focus-group interviews to answer what works for whom and under which circumstances. This will give the investigators additional insights into the novel PSE intervention, shedding light on how it induces change and uncovering any potential unintended consequences. This will support future implementation pending results.

Inclusion Criteria:

• Patients referred for rehabilitation in the municipalities Køge, Holbæk, and Solrød
• With chronic (>3 months) musculoskeletal pain.
• Adult patients (≥18 years) - no upper limit
• Able to understand, speak, and write Danish.

Exclusion Criteria:

• Known cognitive deficits (e.g., dementia).
• Diagnosed with cancer or other serious pathologies, e.g., cauda equina.
• Pregnancy
• Drug addiction defined as the use of cannabis, opioids, or other drugs.
• Neurologic or psychiatric diagnoses that hinder participation, e.g., stroke and borderline.
• Lack of ability to cooperate.

Randomization will be stratified by cite. Block randomization in random concealed block sizes of 4 to 6 (1:1) into two parallel groups is used to avoid imbalance in the randomization between intervention groups. A person not otherwise affiliated with the study will generate the randomization sequence.The randomization will be coded (Group 1 or 2), thus the primary investigator (BE) will not know the code to the groups.