Lifestyle Intervention in Overweight/Obese Chronic Low Back Pain (CLBP) Patients: an International Multi-center RCT

Rationale:

Chronic low back pain (CLBP) is the most common and important clinical, social, economic, and public health problem of all chronic pain disorders across the world. In addition to its high prevalence, CLBP is a severely disabling disorder characterized by tremendous personal and socioeconomic impact. Furthermore, it is the most common cause of work-related disability, generating long-term sick-leaves, and it causes the highest number of years lived with disability.

The most severe and debilitated CLBP patients often have comorbidities such as overweight and obesity. In fact, pain intensity and disability in people with CLBP show dose-responses to body mass index (BMI), waist circumference, percent fat and fat mass. Ample studies and several meta-analyses indeed confirm that overweight and obesity are associated with LBP, with overweight and obesity even being a risk factors for low back pain. Regarding socio-economic impact, overweight or obesity is not only related to LBP persistence, but also to higher rates of health care seeking for LBP. Obviously, people with CLBP who are overweight or obese, are likely to have more complex health needs requiring focus on lifestyle behavioral factors such as physical activity/exercise and diet.

CLBP is a complex disorder which is difficult to treat. Exercise therapy is an evidence-based treatment for CLBP both general exercises and cognition-targeted exercise therapy have shown beneficial effects on pain in patients with CLBP. Unfortunately, current treatments for CLBP apply a 'one-size-fits-all' approach and do not address comorbidities like obesity. This knowledge gap is now acknowledged internationally: overweight and obesity are increasingly recognized as a plausible therapeutic target for people with CLBP. Despite the growing body of scientific literature pointing towards the close interaction between overweight/obesity and CLBP few treatment programs for people with CLBP nowadays take overweight into account.

Few studies explored the added value of weight reduction to the management of people with CLBP. Yet, proof of concept for combining dietary changes with exercise therapy for patients with CLBP and comorbid overweight/obesity show promising results. Here we propose studying the added value of a behavioral weight reduction program (changes in diet, behavior, and physical exercise) to blended rehabilitation (PNE plus CTET) for overweight or obese people with CLBP. Both treatments are effective in their specific target population (i.e., behavioral weight reduction for overweight/obese people and PNE plus CTET for people with CLBP and normal BMI), but whether their combined approach is cumulative in overweight/obese people with CLBP is currently unknown and represents an important research priority.

Objectives:

The primary objective is to examine if a behavioral weight reduction program combined with Pain Neuroscience Education (PNE) and Cognition-Targeted Exercise Therapy (CTET) is superior to reduce pain at 12 months follow-up compared PNE and CTET alone, in overweight or obese people with CLBP.

Secondary objectives are to examine the effects of adding a behavioral weight reduction program combined with PNE and CTET, compared to PNE and CTET alone, on 1) other pain related outcomes (pain interference, pain distribution and pain beliefs), 2) on anthropometrics (body weight/composition, muscle thickness and fat distribution), 3) on energy balance related behavior (24h continuous activity monitoring, dietary intake and sleep) and finally 4) on health economics (heath care utilization, productivity loss and quality of life) at 12 months follow-up.

Interventions:

Both interventions (experimental and control) are organized equally: all participants will receive 18 treatment sessions over a 14-week period see table 2 for a detailed overview. Rather than practical, treatment arms will differ in content.

The control intervention will consist of a total of 18 treatment sessions distributed over 14 weeks. It comprises of only the chronic-pain-focused interventions: 3 sessions of PNE in the first 2 weeks \& secondly, 15 sessions of CTET in the remaining 12 weeks.

The experimental intervention will consist of a total of 18 treatment sessions distributed over 14 weeks. The first part will consist of chronic-pain-focused interventions: firstly, 3 sessions of PNE in the first 2 weeks \& secondly, 15 sessions of CTET in the remaining 12 weeks. The second part will consist of a more weight-reduction-focused intervention. The weight reduction intervention is a lifestyle approach that will be integrated in the CTET intervention, implying that grading daily physical activity and exercise levels will aim at reducing weight (i.e. together with a change in diet we aim at a caloric deficit of 500 to 700 kcal/day) and improving pain cognitions at the same time.

Study design:

Randomized controlled trial with follow-up assessments directly post-treatment (T1), 3 months post-treatment (T2), 6 months post-treatment (T3), 9 months post-treatment (T4) and 12 months post-treatment (T5).

• Brief Pain Inventory - Pain intensity (Average, worst, least, now) [Time frame: This outcome will be assessed at Baseline, directly post-treatment, 3 months post-treatment, 6 months post-treatment and 12 months past-treatment]
• Brief Pain Inventory - Pain interference on functioning [Time frame: This outcome will be assessed at Baseline, directly post-treatment, 3 months post-treatment, 6 months post-treatment and 12 months past-treatment]
• Pain distribution and pain extent by pain drawings [Time frame: This outcome will be assessed at Baseline, directly post-treatment, and 12 months past-treatment]
• Tampa Scale for Kinesiophobia (TSK) [Time frame: This outcome will be assessed at Baseline, directly post-treatment, 3 months post-treatment, 6 months post-treatment and 12 months past-treatment]
• Fear Avoidance Belief Questionnaire [Time frame: This outcome will be assessed at Baseline, directly post-treatment, 3 months post-treatment, 6 months post-treatment and 12 months past-treatment]
• Body weight - Tanita [Time frame: This outcome will be assessed at Baseline, directly post-treatment, and 12 months past-treatment]
• BMI - Tanita [Time frame: This outcome will be assessed at Baseline, directly post-treatment, and 12 months past-treatment]
• Fat mass - Tanita [Time frame: This outcome will be assessed at Baseline, directly post-treatment, and 12 months past-treatment]
• Fat free mass - Tanita [Time frame: This outcome will be assessed at Baseline, directly post-treatment, and 12 months past-treatment]
• Muscle mass - Tanita [Time frame: This outcome will be assessed at Baseline, directly post-treatment, and 12 months past-treatment]
• Body Water - Tanita [Time frame: This outcome will be assessed at Baseline, directly post-treatment, and 12 months past-treatment]
• Waist-hip circumference [Time frame: This outcome will be assessed at Baseline, directly post-treatment, and 12 months past-treatment]