Mindfulness-Based Pain Management (MBPM) is an eight-week behavioral medicine program. Based on the well-known Mindfulness-Based Stress Reduction (MBSR) program, it was specifically developed as an intervention for chronic pain. During the program, mindfulness exercises, gentle body exercises and body awareness and breathing exercises, as well as pain regulation methods are taught.

Initial studies suggest efficacy of the program with regard to chronic pain, however, the effect of the standardized program in patients with chronic musculoskeletal pain has not yet been investigated in a clinical study. Therefore, the aim of this study is to investigate the MBPM program on pain acceptance in patients with chronic musculoskeletal pain. To this end, 40 patients with chronic (specific and non-specific) musculoskeletal pain will be randomly assigned to two study conditions. The intervention group will receive MBPM sessions of 150 minutes once a week over the course of 8 weeks, while the control group will receive standard therapy (waiting list). We hypothesize that patients will indicate a significantly higher pain acceptance after completing the program compared to patients not participating in the program.

The purpose of this study is to investigate the efficacy of a structured 8-week Mindfulness-Based Pain Management (MBPM) program, based on the Breathworks method by Vidyamala Burch, in addition to standard therapy compared to standard therapy alone in terms of pain acceptance in patients with chronic musculoskeletal pain.

The study is a monocentric, single-blinded (data collector), randomized study with 2 study arms. Study center is the Clinic for Natural and Integrative Medicine, Evang. Kliniken Essen-Mitte.

Patients will be recruited via study calls on the clinic website as well as via press advertisements (see appendix). In addition, former patients who have been treated at the Clinic for Natural and Integrative Medicine for chronic musculoskeletal pain will be contacted. If a patient reports interest in the study, he/she will first be screened by telephone for the presence of the inclusion and exclusion criteria. In case of potential eligibility, patients are invited to the Study Center. All patients will be informed by a study physician and assessed for suitability to participate in the study.

The inclusion and exclusion criteria are assessed on site by the study physician by means of a detailed general medical history and an orienting clinical-neurological examination.

Eligible patients will be assigned to one of the two study arms after completion of measurements at week 0 via non-stratified block randomization with randomly varying block length. Establishing the randomization sequence and ensuring blinded assignment will be done via central randomization through RedCap software by an external researcher who will have no patient contact throughout the study. Neither the patients nor the study physician nor the study coordinators will have any insight into the randomization sequence.

The study has 3 defined measurement time points: A baseline measurement (week 0) before randomization, at which time all standardized questionnaires as well as patient-specific data on sociodemographics (age, height, gender, weight, socioeconomic status), lifestyle, duration of disease, previous and currently applied therapies will be asked, and further measurement time points at the end of the course 8 weeks after randomization (week 8) and 6 months after randomization (week 26).

The sample size calculation was based on a non-randomized study by Cusens et al (2010), which found a large effect size of d=1.04 for pain acceptance for MBPM in addition to standard therapy compared to standard therapy alone. Based on a power (1-) of 80%, a significance level of 5%, and an anticipated dropout rate of up to 20%, a 2-sided t-test requires a total sample size of 40 patients (20 patients per group) to detect such an effect.

All analyses are based on the intention-to-treat population, i.e., all patients enrolled in the study are evaluated in the group originally assigned to them regardless of the treatment actually received. Missing values will be replaced using standard imputation procedures.

The primary outcome parameter will be analyzed confirmatively using univariate analysis of covariance (ANCOVA), in which the main outcome parameter will be modeled as a function of group membership (binary co-variate), respective baseline values (linear covariate), and expectancy (linear covariate). Within this model, the adjusted group difference (including 95% confidence interval) is estimated and tested for superiority of the intervention over the control group using a two-sided t-test at the α=0.05 level. Secondary end points will be evaluated exploratively using the same models as the primary end point. Change scores (change scores) and effect sizes (hedges' g) for between-group comparisons will be calculated to assess the clinical significance of the results.

The influence of potential process variables will be investigated using multiple mediator analyses.

Inclusion Criteria:

- Chronic specific or nonspecific musculoskeletal pain for at least 3 months

Exclusion Criteria:

New diagnosis within the last 3 months of:

• Degenerative diseases (e.g., herniated disc, spinal stenosis)
• Neurological diseases (e.g., neuropathies, multiple sclerosis)
• Injuries of the spinal column (e.g. due to whiplash, vertebral body fractures, operations)

Or severe concurrent diagnosis of:

• Severe comorbid mental illness (e.g. addiction, severe depression)
• Severe comorbid physical illness (e.g. cancer diagnosis within the last 5 years, severe preexisting disease of the cardiovascular system, insufficiency of other organs (kidney, liver, etc.), acute febrile infection, other severe neurological diseases such as epilepsy)
• Pregnancy
• Current pension application (for work incapacity, occupational disability, reduction in earning capacity, severe disability)
• Simultaneous participation in other clinical trials

Data collectors will be blinded. Blinding of study participants is not possible due to the study design.