Obesity is a major public health problem in our region and constitutes a priority of the Canary Islands Health Plan. Bariatric surgery is the most effective intervention in the treatment of obesity and its complications. However, people with obesity have high surgical risk and long-term outcomes are related to pre-surgical weight loss.

In patients currently on the bariatric surgery waiting list, a randomized controlled trial will be performed in which two group interventions will be compared. One of the interventions (standard), will consist of educational modules in food and exercise, combined with cognitive-behavioral therapy. In the other, a specific training (prehabilitation) will be added to encourage physical activity and the conditioning of inspiratory muscles.

The pre-surgical weight loss (principal outcome) will be compared between groups, as well as the evolution of the complications of obesity, the functional status of the patients, their physical activity, quality of life, immediate complications of surgery and days of admission.

Obesity is a major public health problem, responsible for an increased risk of hypertension, obesity, dyslipidemia, type 2 diabetes, cardiovascular disease, some types of cancer, psychiatric diseases and mortality.

Bariatric surgery has proven to be the most effective method for reducing weight and related comorbidities in patients with morbid obesity. However, pre-surgical weight loss reduces postsurgical complications. In addition, weight loss before surgery seems to be the only factor positively associated with post-surgical weight loss, and this effect seems to be more pronounced in patients with BMI> 45 kg / m2.

Pre-operative physical conditioning (prehabilitation) can improve the patient's functional capacity before major surgery. Most studies showing this have been conducted in orthopedic surgery and abdominal cancer surgery. There are very few studies that evaluate prehabilitation in patients undergoing bariatric surgery.

Objective

Comparison of a multidisciplinary group intervention with another one to which specific training focused on increasing physical activity is added, in patients on the surgical waiting list for bariatric surgery in a randomized controlled trial.

Methods

Design Randomized, controlled parallel group, clinical trial.

Intervention Duration: 4-month intervention, with biweekly 2,5-hour group sessions, followed by a monthly reinforcement session of 1h until surgery.

Intervention A: Educational program and cognitive-behavioral intervention (control group)

Intervention B: Educational program and cognitive-behavioral intervention, with specific training aimed at increasing physical activity, functional capacity and conditioning of the respiratory muscles (intervention group).

Study population The recruitment of the participants will be made from the waiting list of bariatric surgery (obesity II-IV), selecting patients with estimated waiting time above 4 months. Patients will be excluded if any reason for inadequate follow-up is identified, according to the investigators criteria.

Ethical aspects The design and execution of this study will be done in accordance with the Declaration of Helsinki and the homogenized European guidelines of good clinical practice. Before their participation, the patients will sign an informed consent form. The protocol has been approved by the local ethics committee

Sample size Based on the size of the waiting list for bariatric surgery, with a mean duration of 17 months, and that the intervention is considered feasible on two groups of 10 people, in parallel, in each branch, (a weekly session of 2h per nutrition nurse, with support from additional professional). Starting with a pilot group of each intervention and taking into account an overlap between them, in 18 months about 60-80 patients could be included in total.

With 80 patients included, without losses, and assuming a standard deviation of weight of 11Kg, and for a bilateral p <0.05 a difference between groups of 7 and 8Kg, with a statistical power of 80 and 90%, respectively. If we assume a standard deviation of 6Kg, as shown by other studies, the detectable difference would be reduced to about 4Kg.

Statistical analysis A descriptive analysis of the baseline situation will be made. The qualitative variables are expressed as a percentage, quantitative, as mean (SD) or median, according to if its distribution is normal or not, respectively. Comparisons will be made between treatment groups, using chi squared for qualitative variables and Student's t or Mann Whitney's U for quantitative variables. The analysis of results will be done by intention to treat analysis. That is, all patients who have baseline data and have been randomized, will be included, regardless of their subsequent attendance to the Program.

Inclusion Criteria:

• People with obesity (type II-IV), on the waiting list for bariatric surgery in the Complejo Hospitalario Universitario Materno-infantil de Las Palmas

Exclusion Criteria:

• any factor that, in the opinion of the researchers, limits the ability to monitor the intervention (language barrier, ...).

Anonymized data will be shared upon request

After publication of the results

Reasonable plan, acknowledgement of original investigators

A person external to the monitoring and evaluation of the patients will generate a random sequence (by computer), to assign the participants to their corresponding treatment group. The intervention sequence will be transcribed to cards that will be introduced in an envelope each. The envelopes will be opaque, sealed and numbered consecutively. Each time a patient agrees to participate in the trial, he/she signs the informed consent and we verify that he/she meets the inclusion criteria, but not the exclusion criteria, the corresponding envelope will be opened in correlative order.

Patients will be assigned to one of two group interventions, unaware of the components in each group. The assessment of most of the outcomes will be blinded, too.