Short summary

Chronic back pain is one of the most expensive and disabling conditions worldwide with few effective treatment options. More than 50% of chronic back pain patients also have insomnia. This randomized controlled trial intends to investigate the pain relieving potential of Melatonin for chronic back pain, a widely used drug for treatment of sleep disorders and jetlag with a favourable safety profile.

Rationale

Chronic back pain is a public health problem associated with reduced quality of life, disabling conditions and increasing socioeconomic burden worldwide. According to the World Health Organization (WHO) Global Burden of Disease study, back pain is one of the leading causes of disability worldwide, but the amounts of available and effective treatments for patients with chronic back pain are few. The analgesic use, such as paracetamol, non-steroidal anti-inflammatory drugs (NSAIDs), muscle relaxants and opioids, in patients with chronic back pain are extensive compared to the limited evidence of efficacy, where the effects are generally less than 10 points on a 0-100 pain scale. Furthermore, these analgesics, especially NSAIDs and opioids, are associated with a risk of adverse effects such as gastrointestinal side effects for NSAIDs and addiction for opiods. Furthermore, insomnia is reported by more than 50 % of patients with chronic back pain, and it has been reported that insomnia has a negative impact on pain processing - it has been reported to reduce the pain threshold. A reciprocal relationship between pain and insomnia has been described in the literature, where the evidence suggests insomnia to be a better predictor of pain than the other way. Therefore, treatment of sleep could be a possible pathway to improve pain. Melatonin is a hormone excreted by the pineal gland and has an important role in the circadian rhythm. Melatonin is widely used to treat jetlag and insomia11 and it has a favorable safety profile regarding clinical adverse events, which is a big advantage compared to other drugs used for pain treatment. A recently published meta-analysis has reported the pain reducing effect of melatonin in non-musculoskeletal chronic pain such as irritable bowel syndrome, burning mouth syndrome and migraine). Results from previous small non-controlled clinical trials suggests that melatonin could have a pain relieving effect on chronic musculoskeletal pain and fibromyalgia, however this needs to be further investigated The aim of this randomized double-blind placebo controlled clinical superiority trial is to investigate the efficacy of 10 mg/daily Melatonin for 6 weeks compared with placebo on pain intensity for patients with chronic back pain.

Description of the cohort

220 adult participants with chronic backpain will be included through advertisements, and social media. The inclusion and exclusion assessment will be done at the Pain Center, Department of Anesthesiology and Intensive Care Medicine, University Hospital Odense.

Data and biological material

1. Questionnaire data on pain, sleep, and health-related quality of life. 2. Sleep data from ear electroencephalography (EEG) device (subgroup of 60 patients). 3. Measurement of pressure pain threshold (pain sensitivity).

Collaborating researchers and departments

Department of Anesthesiology and Intensive Care Medicine, Odense University Hospital, and Department of Clinical Research, Faculty of Health Sciences, University of Southern Denmark.

• Professor and co-supervisor, Henrik Bjarke Vægter
• Consultant, and PhD, Karin Due Bruun

Research Unit for General Practice, Department of Public Health, University of Southern Denmark and Department for General Practice, Erasmus University Medical Center, Rotterdam, The Netherlands

• Bart Willem Koes, Professor and co-supervisor

Center for Muscle and Joint Health, Department of Sports Science and Clinical Biomechanics, and Research Unit for General Practice, Department of Public Health, University of Southern Denmark

• Professor and co-supervisor, Jonas Bloch Thorlund

Department of Electrical and Computer Engineering, Aarhus University.

• Professor, Preben Kidmose

Center for Muscle and Joint Health, Department of Sports Science and Clinical Biomechanics, University of Southern Denmark and Chiropractic Knowledge Hub, Odense, Denmark

• Professor, Jan Hartvigsen

Research Unit for General Practice, Department of Public Health, University of Southern Denmark

• Professor, Jens Søndergaard