Long-term trajectories of weight loss and health outcomes: protocol of the SCOOP-RNPC nationwide observational study

STRENGTHS AND LIMITATIONS OF THIS STUDY

  • Large (>10 000 participants), prospective cohort, real-world evidence.

  • Multicentric recruitment (92 centres) covering the whole of France.

  • Long-term (5-year) prospective follow-up.

  • Multidimensional longitudinal data (patient-reported outcome measures, comorbidities, medications, objective sleep data, sleep apnoea, physical activity, arterial stiffness).

  • Observational, non-randomised study.

Introduction

According to the WHO, 4 million people die every year as a consequence of being overweight or obese. Obesity is nowadays recognised as one of the most frequent chronic diseases of the 21st century.1 It is a major burden both on affected individuals, health systems and society as a whole.

Excess weight contributes significantly to the occurrence of chronic metabolic and cardiovascular diseases including hypertension, coronary heart disease, stroke, dyslipidaemia, type 2 diabetes, sleep apnoea syndrome and non-alcoholic steatohepatitis (NASH) as well as some specific cancers.2 It impacts on osteoarticular diseases, such as osteoarthritis, and psychological disorders such as depression and has a deleterious effect on quality of life. The risk of occurrence, accumulation and progression of these non-communicable diseases is exacerbated in overweight individuals compared to people of normal weight, with an exponentially increasing risk the greater the degree of obesity.3

The increase in the prevalence of overweight and obesity has major economic consequences because patients with obesity significantly impact health expenditures owing to their frequency of comorbidities, associated hospitalisations and emergency room visits.4 According to estimates issued in 2016 by the French Ministry of Economy and Finance, individuals with obesity, while representing only 15% of the population account for 22.1% of the burden put on health services and percentage of gross domestic product.5

All international recommendations advocate lifestyle and dietary measures as the first-line management for patients at high cardiometabolic risk6–8 with weight loss as the primary objective. Studies are consistent in demonstrating that even a modest weight loss, especially if maintained over time, can improve cardiometabolic risk. The percentage of remission for diseases like atrial fibrillation,9 diabetes,10 NASH11 and obstructive sleep apnoea syndrome (OSAS)12 increases with the percentage of weight loss, reaching almost 90% for a weight loss greater than 10–15%.

Sleep is also an important component in weight management as sleep restriction has been associated with body weight gain and obesity in numerous epidemiological studies.13 Sleep deprivation induces greater appetite and energy intake as well as less energy expenditure.14 Additionally, being overweight or obese increases the risk of developing OSAS.15 The combination of OSAS with obesity has a synergistic effect in aggravating cardiometabolic comorbidities.16 Weight loss correlates with reductions in severity and remission of OSAS.12

The French Nutritional Psycho-Behavioural Re-education Programme (RNPC for Rééducation Nutritionnelle et Psycho-Comportementale), weight loss programme, offers physicians a solution for delegating the management of their patients with overweight/obesity to qualified dietitians in a real-life setting. This national programme has already provided retrospectively collected data.17 Out of 12 179 individuals included in the RNPC Programme, 89% completed the weight loss phase of the programme in 105 days, losing 11% of their initial body weight.17 The analysis of data from the 2996 patients of the RNPC cohort who followed the entire programme (ie, the weight loss phase and the stabilisation phase) showed that these patients had lost another 6% of initial body weight during the stabilisation phase (ie, 17% in total, in 251 days17). In a retrospective study, we found overall improvements in most metabolic parameters demonstrating a better control of diseases associated with metabolic dysfunction, such as type 2 diabetes, cardiovascular diseases and NASH.18 Also, in a prospective study, we have demonstrated that such a weight loss programme produced a significant improvement in both OSAS symptoms and subjective daytime sleepiness, but objective data regarding apnoea-hypopnoea index measurements were not available after weight reduction.19

The main problem with weight loss diets is the high rate of weight regain after the initial loss.20 Real-world data on long-term (up to 5 years) weight loss, obesity-related complications, remission of comorbidities and sleep health after weight-loss rehabilitation programmes are currently limited.21 The primary objective of this study is to demonstrate the effectiveness of the national RNPC weight reduction programme in decreasing the need for drugs for comorbidities or continuous positive airway pressure (CPAP) treatment for sleep apnoea, and/or by inducing remission of comorbidities at the end of the stabilisation phase. The secondary objectives are shown in table 1.

Table 1

Secondary objectives, description of endpoints and times of assessments

About 10 000 overweight or obese participants will be included over 2 years with a length of follow-up of up to 5 years.

Materials and methods

Study design

The SCOOP-RNPC is a prospective multicentre cohort study, conducted in real-life conditions. Participants follow a standardised nutritional rehabilitation programme conducted in 92 of the 110 RNPC centres distributed throughout France (see online supplemental figure S1 for geographical distribution of RNPC centres in France).

Supplemental material

Planned start and end dates

Ten thousand patients will be included over a period of 2 years starting 2 October 2023 and will be followed for 5 years. The estimated end of the study date is between 1 December 2028 and 1 September 2030, depending on the flow of inclusions.

Participants and setting

Selection criteria: inclusion in the prospective cohort is offered to all individuals coming to one of the participating French RNPC centres (on their own initiative or referred by their general practitioner), meeting the inclusion criteria and starting the nutritional rehabilitation programme. All adults (age between 18 and 85 years), overweight or obese (body mass index (BMI) greater than or equal to 25 kg/m²) and eager to follow the RNPC Programme in the RNPC investigator centres are potentially eligible for the study. Pregnant, parturient and breastfeeding women, persons with missing limb(s), people with an electrical medical device such as a pacemaker, battery operated implant, insulin pump, cochlear implant and people having any implanted metallic material, such as prostheses or screws, are not eligible for this study.

Sample size: the number of subjects required was calculated to show a significant difference in the evolution of the number of treatments and or dosage before and after the intervention (RNPC Programme) with an SD of 5 units and a weak correlation between the measurements (strong hypothesis). A sample size of 608 patients is necessary to compare the mean number of treatments in the subgroup with the lowest prevalence (dyslipidaemia). Taking into account participants who dropout over time, and to assess the long-term effect, a sample size of 700 patients for the dyslipidaemia subgroup is necessary. Considering a prevalence of this subgroup of 7%, the total group should consist of at least 10 000 patients.

In addition, within the main study cohort, different subgroups are created to address secondary objectives that require a particular measurement device outside of routine care (Sunrise device for OSAS, Body Comp scales for pulse wave velocity (PWV), and Sudoscan/EZscan for peripheral neuropathies).

  • To analyse the evolution of OSAS over time with the Sunrise device, a sample of 790 patients will be included to demonstrate a mean reduction in Apnoea-Hypopnea Index (AHI) of 10 events by hour with a SD of 30 including 20% of withdrawals. This sample considers a prevalence of OSAS of 50% at inclusion.

  • A PWV analysis will be based on a sample of 500 patients allowing to highlight a mean reduction of 1 m/s±7 with a power of 0.8.

  • For peripheric neuropathy measured by Sudoscan/EZscan, at least 100 patients with two measures will be included to demonstrate a difference in conductance of 20 µA with a SD of 50 µA compared with the initial measure with a power of 80%.

Feasibility

Given the selection criteria, participation in this study is offered to approximately half of the patients seen in the investigating centres as part of the routine care activity of French RNPC centres. For information, in year 2021, 10 137 new patients were treated in the RNPC network (at that time, made up of 85 centres).

In addition, the number of RNPC centres in France is expected to increase during the recruitment period. in October 2023, when recruitment began, the network was made up of more than 110 centres spread across France, 92 of which participated in the study. After 1 year of recruitment (summer 2024), an amendment to the protocol will be submitted to the ethics committee, so that around 10 other investigative centres can be involved in the recruitment of participants in this study.

Description of the intervention

The RNPC Programme has been previously fully described17 and is summarised elsewhere.19 Briefly, the method is based on a clinical protocol with three successive phases:

  1. A weight loss phase during which food intake is restricted to 800–1000 kcal per day, with a nutrient distribution of 60% protein, 25% carbohydrates and 15% lipids. Patients eat two meals a day consisting of meat/fish/eggs/shellfish and vegetables, supplemented by products enriched in proteins, vitamins and minerals and depleted in carbohydrates and lipids. The median (IQR) number of days to complete the weight loss phase is 105 (56; 175).

    Apart from any pathology requiring an adaptation of the dietary programme (renal insufficiency, which requires restriction in the amount of protein), this first phase of the dietary intervention is the same for all participants, regardless of the initial BMI. For information, initial BMIs of patients following the RNPC Programme are distributed as follows: 30% with BMI <30, 37% with BMI ≥30–<35, 21% with BMI ≥35–<40, 8% with BMI ≥40–<45 and 4% with BMI ≥45.18 Only the weight objective at the end of the first phase of the intervention is different.

  2. A stabilisation phase personalised for each patient according to their weight loss in phase 1 and their daily caloric needs, allowing them to gradually return to a balanced diet, with a nutrient distribution of 25% protein, 45% carbohydrates and 30% fats. During this phase, the consumption of meal supplements is gradually decreased. The median (IQR) number of days to complete the weight stabilisation phase is 251 (187; 350).

  3. A phase of return to dietary balance, unlimited in time, based on the precepts of the Mediterranean diet.

Each patient is followed every 14 days by a dietitian during the entire programme.

Study objectives and endpoints

The primary objective is to demonstrate the effectiveness of the national RNPC weight reduction programme in decreasing the need for drugs for comorbidities or CPAP treatment for sleep apnoea and/or by inducing remission of comorbidities at the end of the stabilisation phase (minimum duration of 6 months but not exceeding 1 year).

The primary endpoint of the SCOOP-RNPC study is a composite endpoint defined as the percentage of participants with at least one dose reduction or suppression of their initial medications for comorbidities and/or CPAP treatment for OSAS and/or remission of at least one comorbidity (hypertension, type 2 diabetes, dyslipidaemia or OSAS) at the end of the stabilisation phase.

The secondary objectives and endpoints are detailed in table 1.

Subgroup analyses will be performed for each comorbidity separately: hypertension, type 2 diabetes, dyslipidaemia and OSAS. Moreover, the different strategies of treatment over time will be assessed: (1) percentage of patients who had no change in their initial treatment during the follow-up (absence or presence of a treatment over time), (2) percentage of patients who have an increase in dose or number of treatments during the follow-up and (3) percentage of patients without initial treatment and who start a treatment during follow-up.

Data collection during the different visits

In this prospective observational cohort study, we collect clinical, anthropometric and analytical laboratory data, comorbidities, medications, body composition, patient-reported outcomes questionnaire responses, surrogate markers of cardiovascular risk (ie, blood pressure and arterial stiffness), rates of comorbidity remission and percentages of patients with reduction in diabetes, hypertension and lipid-lowering drugs.

A summary of data to be collected is shown in figure 1.

Figure 1
Figure 1

Overview of data collected. 1. Trajectories of overall state of heath (primary objective; in grey) 2. Trajectories of anthropometric and body composition parameters (in black) 3. Trajectories of biological parameters (in orange) 4. Trajectories of patient reported outcomes (in blue) 5. Trajectories of physical activity (in green) 6. Trajectories of sleep health (in purple) 7. Trajectories of surrogate markers of cardiometabolic risk (in red) 8. (Trajectories of subgroup with or without 10% reduction in initial weight). Data collected by two different means (sleep-related data and physical activity) are coloured in the two corresponding colours. ESS, Epworth Sleepiness Scale; FFQ, Food Frequency Questionnaire; HAD, Hospital Anxiety and Depression; ISI, Insomnia Severity Index; OSAS, obstructive sleep apnoea syndrome; PSQI, Pittsburgh Sleep Quality Index; PSS, Perceived Stress Scale; QOLOD, Quality Of Life, Obesity and Dietetics; TFEQ, Three-Factor Eating Questionnaire; VAS, Visual Analogue Scale.

Questionnaires to evaluate different dimensions of patient-reported outcome measures

All questionnaires are self-administered, so they are completed online at the patient’s home between two face-to-face consultations at the RNPC centre (table 2). Determination of completion rates will be made by the dietitians and a quality control of responses will be made by analysts.

Table 2

Summary of participant monitoring

Sleep-related questionnaires

The Epworth Sleepiness Scale22 (1), the Pittsburgh Sleep Quality Index23 (2), the Insomnia Severity Index24 (3) and the determination of Sleep Chronotype25 (4) will assess sleep-related parameters and profile.

Food intake, eating behaviour questionnaires

As part of a dietary intervention where food intake is controlled, it seems essential to accurately determine calorie intake, and use of macronutrients (proteins, carbohydrates, lipids, fibres) and micronutrients (vitamins and minerals) over the year before the weight-loss programme initiation using the Food Frequency Questionnaire26 (5). This questionnaire contains no less than 183 questions and requires an average response time of 45 min, which represents a significant constraint for participants. Thus, we chose to submit this questionnaire to them only once, before the intervention.

Eating disorders, which can play a role in the ability to maintain weight loss after a dietary intervention, will be determined by the Three-Factor Eating Questionnaire27 28 (6).

Physical activity and energy expenditure questionnaires

Like food intake, energy expenditure is a determining factor in weight regulation and needs to be considered in the analysis of weight trajectories. The Baecke questionnaire29(7) will help to determine the level of overall daily physical activity of the participant during the RNPC programme.

Emotional state, anxiety and depression

The links between the emotional state (anxiety, depression) and weight regulation are fully demonstrated. The Perceived Stress Scale30 (8) and the Hospital Anxiety and Depression scale31 (9) will be used to assess these aspects in the SCOOP-RNPC participants.

Characterisation of patient ecosystem, quality of life questionnaires and patient-reported outcome measures

A general questionnaire (10) written for the purposes of the study will provide relevant information on the participant’s living environment, their family situation and socioeconomic level, which have been suggested as determining factors for weight status at a population level. Participants will respond to this questionnaire once after the inclusion visit and every year after the end of the intervention during the 5 years of follow-up.

Quality-of-life questionnaires are essential for the evaluation of the impact of an intervention at both the individual and societal levels. Two quality-of-life assessment questionnaires have been selected for this study: the EQ-5D-5L 32 (11), a relatively short and concise general questionnaire, and the Quality of Life, Obesity and Dietetics (or EQVOD for Échelle Qualité de Vie, Obésité et Diététique) questionnaire 33 (12), a French-specific questionnaire for overweight patients.

Pain assessment

The association between obesity and osteoarthritis, and specifically the role of obesity as a risk factor for osteoarthritis has been well documented.34 Every month, the subjects will self-assess their sensation of osteoarthritis-related pain and shortness of breath using a visual analogue scale. This self-reported pain scale has been shown to be sensitive, reproducible and reliable and has been validated in both acute and chronic pain situations.35

Alcohol and tobacco consumption

Information regarding alcohol and tobacco consumption will be collected by the dietitian, at each visit.

Clinical data and objective measurements of the different health dimensions

Anthropometrics, body composition, comorbidities and medications

All clinical parameters, comorbidities and medications will be collected at each visit via an electronic research file.

The patient’s height will be measured during their first visit to the RNPC centre. At each visit, every 14 days, the subject will be weighed on an impedance balance (Beurer BF-1000), making it possible to evaluate the percentages of lean, fat and water masses and to calculate the BMI. Waist circumference, obtained by measuring abdominal circumference with a tape measure, is an indicator of visceral adiposity related to prognosis. Neck circumference, a predictor of sleep apnoea, will also be measured.

Comorbidities will be recorded as ICD-10 codes and medications as Anatomical Therapeutic Chemical (ATC) codes with the dosages.

Biological parameters

Biological data will be obtained from fasting blood and urine samples collected on three occasions during the protocol (table 2). Analyses will include complete blood cell count, erythrocyte sedimentation rate, fasting blood glucose and insulin, HbA1c, lipid profile, creatininemia, creatininuria, microalbuminuria, plasma ionogram, uricemia, uremia, transaminases such as aspartate aminotransferase (AST), alanine aminotransferase (ALT) and gamma-glutamyl transferase (GGT), thyroid-stimulating hormone (TSH) and ferritinemia.

Objective measures of sleep health

The Sunrise medical device (Sunrise) will be used to objectively investigate sleep at the participants’ home. It consists of a sensor placed on the chin, allowing a complete evaluation of sleep and sleep apnoea severity. The performance of the device has been extensively validated in different clinical settings.36 37

Surrogate markers of cardiometabolic risk

Blood pressure

Blood pressure will be measured repeatedly three consecutive times38 at each RNPC centre visit using a blood pressure self-measurement device (OMRON, model M6W) and under the supervision of a trained dietitian.

Number of steps and distance covered

The investigating dietitian will ask the participant to download a pedometer application onto their smartphone so as to collect, at each visit, the number of steps and the distance covered during the past week.

Arterial stiffness, heart rate and peripheral neuropathies

The Body Comp impedance scale (Withings) will be used to measure PWV, by the contact of the feet on the scales.39 PWV, which depends on the age of the subject, reflects arterial stiffness and makes it possible to assess cardiovascular risk. Other collected data include weight, BMI, fat mass (in kg and %), bone mass (in kg and %), muscle mass (in kg and %), percentage of body water, heart rate and signs of peripheral neuropathies.

Sudoscan/EZscan technology (Withings) will be used to measure the ability of autonomic sweat glands to release chloride ions in response to an electrochemical stimulus, with chloride conductance (measured in microsiemens) serving as a biomarker for the early detection of peripheral neuropathies. The device also makes it possible to identify people at increased risk of diabetes (including pre-diabetes),40 based on a score expressed as a percentage of risk, ranging from 0% to 100%.

Study flow

The sequence of visits during the study as well as the timing of the different examinations is shown in table 2.

Within the framework of the RNPC weight management programme, the medical follow-up is carried out by one or more doctors (GP and/or specialist) that the patient is used to consulting. The dietitians are solely responsible for collecting the data for monitoring patients as part of the RNPC Programme.

Preselection

To follow the RNPC Programme, patients generally contact the RNPC centre of their choice by telephone. The preselection phone call is quite brief. Dietitians ask patients their age, height and weight to calculate their BMI, their known pathologies and their contact details to send them the list of biological analyses to be carried out before the day of the appointment at the centre. These few questions by telephone make it possible to find out whether they are eligible to (1) follow the RNPC programme and (2) to participate in the study (the age and/or BMI of certain people allow them to follow the programme without being eligible to participate in the study). If the patient can at least follow the programme, a visit to the centre is scheduled.

Selection and inclusion visit

Individuals must obtain authorisation from their GP to start the RNPC Programme as well as a prescription for the study biological analyses, including an evaluation of renal function (creatininemia). We request a routine kidney function assessment as part of monitoring the RNPC Programme for several reasons.

On the one hand, this is a safety measure. In fact, the diet during the weight loss phase is moderately enriched in protein. However, the amount of dietary protein must be strictly controlled and adapted in people with kidney failure, which dietitians do by following the national recommendations of good clinical practice. On the other hand, excess weight, in particular visceral fat that is localised in the abdominal cavity, is a significant risk factor for kidney failure, as is type 2 diabetes and high blood pressure, two comorbidities of overweight/obesity. Like blood pressure and fasting glycaemia, estimated glomerular filtration rate (eGFR) can improve with weight loss.41 It, therefore, seems important to us to evaluate the proportion of participants suffering from renal insufficiency and the evolution of this disease with weight loss.

During the initial visit, the patient is welcomed at the RNPC centre by the dietitian who presents the modalities of RNPC care and gives a detailed explanation of the rationale and the protocol of the RNPC Programme, in a face-to-face interview. The dietitian performs a clinical examination and collects details on medical history, lifestyle, previous and current medical treatments, etc, and records the data from the biological assessment. This visit lasts between 1.5 and 2 hours. All information and data collected at this point are part of normal RNPC monitoring.

At the end of the visit, the investigating dietitian will verify that the subject meets the eligibility criteria, invite him/her to participate in the SCOOP-RNPC study and obtains their signed informed consent. If eligible, depending on the RNPC centre and with the patient’s agreement, he/she may be included in one of the subgroups: ‘OSAS’ subgroup with sleep assessment and diagnosis of OSAS (if applicable) using the Sunrise device, the ‘Connected Objects’ subgroup with use of the Body Comp connected scales for measurement of anthropometric parameters and evaluation of arterial stiffness, or the ‘Neuropathies’ subgroup with use of the Sudoscan/EZscan device for assessment of peripheral neuropathies on inclusion as well as at certain key times during follow-up.

Follow-up visits

As part of the routine care of the RNPC centres, each patient will be followed every 14 days (visits of 30 min) by a qualified dietitian during the entire programme.

End of weight-loss phase visit

As part of the routine care of the RNPC centres, this visit corresponds to when the patient reaches their target weight. A 1-hour visit is then scheduled 14 days later to explain to the patient the terms of the stabilisation phase protocol (minimum duration of 2 months but not exceeding 8 months).

End of stabilisation phase visit

As part of the routine care of the RNPC centres, the end of the stabilisation phase visit corresponds to the end of the usual RNPC Programme (minimum duration of 6 months but not exceeding 1 year).

After the end of the dietary intervention phases, SCOOP-RNPC participants will benefit from the care usually provided by RNPC centres as part of programme follow-up. Usually, subsequent visits to the centre are strongly recommended but optional, the frequency being decided by the patient.

Long-term follow-up of weight-loss maintenance

At the end of the RNPC Programme, study participants will remain in the study for 5 years and will be asked to visit their RNPC centre, at least once a year. They may, if they wish, visit their RNPC centre more frequently. The visit at 1 year and after the end of the stabilisation phase (as well as the following visits) is required and corresponds to the ‘long-term’ evaluation point. There is no exclusion period at the end of this study.

During long-term follow-up visits, the evolution of weight, waist circumference and the occurrence of any medical events will be monitored. Every year, study participants will be asked to complete the study questionnaires, online. Participants will be contacted directly through the study electronic mailing list, and in the absence of feedback, a telephone call may be made by a member of the coordinating centre of the ‘Groupe Éthique et Santé’ to collect the information necessary for long-term follow-up.

Statistical analysis

A description of the data will be made using the median and IQR for quantitative data and the number and percentage for qualitative data. For all objectives, a detailed statistical analysis plan will be defined including consideration of missing data.

For the analysis of the primary objective, the prevalence of the number of patients with a reduction or suppression of their drug and/or device treatments will be calculated with its 95% CI. A comparison of the number of drugs or a medical device before and after the programme will be carried out using a paired Student’s t-test. Subgroup analyses will be performed to assess the primary objective by considering different levels of BMI at baseline, sex, age and comorbidities. To take into account the initial level of treatment and the potential confounding factors (initial weight, age, sex, time between measures, geographical region, etc), a generalised linear model with a mixed effect (random patient effect or even centre effect in addition) will be carried out with a binomial distribution to evaluate the effect of time on the success of the programme defined by the fact of having a decrease in treatment. Finally, other approaches could be applied with a more highly developed statistical analysis plan.

For the analysis of secondary objectives:

  • The analysis of the evolution of anthropometric parameters will be carried out using a generalised linear mixed effects model (patient random effect).

  • The factors associated with the resolution of the objective of a 10% loss in weight will be defined using a predictive approach based on random forest or penalised regression approaches. The objective will be to identify, among all the data collected at the beginning of the programme (quantitative and qualitative, from the interview with the dietitian and the patients’ questionnaires), the factors that can predict success of the programme, that is, a 10% wt reduction after the weight loss phase. All the objectives will be studied by comparing two weight loss groups (10% or more vs less than 10% of initial body weight).

  • The percentage of patients who changed their BMI category at the end of each phase of the programme and its CI will be calculated. Multivariate methods will be used to identify the determinants of these changes.

  • A generalised linear regression model with a mixed effect (patient random effect) will be used to evaluate the associations between weight loss and the evolution of different parameters (pain, biological parameters, blood pressure, sleep quality, OSAS, quality-of-life, eating behaviour, physical activity, stress, anxiety, depression, individual well-being, arterial stiffness, peripheral neuropathy). A search for confounding factors will be performed to allow model adjustment.

Each objective will be the subject of a detailed analysis plan taking into account the amount of missing data and identifying potential imputation strategies. The methods used will also be based on trajectory analysis or clustering approaches allowing the identification of distinct patient profiles and their impact on the results criteria. Trajectory will be defined by weight evolution from baseline, through the stabilisation phase and to the end of the programme. In addition, the analysis of the questionnaires will be subjected to the application of longitudinal data analysis methods applied to qualitative variables.

Patient and public involvement statement

Patients and the public were not involved in the design and planning of the study.

Discussion

Knowledge acquired thanks to the SCOOP-RNPC cohort will have benefits for individual participants, for the scientific community, and for society with better understanding of the impact of weight-loss management on general health at short, medium and long-term.

Responding to the major public health issue represented by growing sections of the population being overweight and obese, this prospective cohort will make it possible to evaluate, in real-life conditions, the effects of weight loss obtained by patients enrolled in the RNPC Programme in the short, medium and long term on biological parameters predictive of cardiometabolic risk, drug consumption, quality of life, diet and eating behaviour, sleep, physical activity, stress/anxiety as well as depression.

This cohort will make it possible to identify clinical phenotypes and biomarkers to optimise the personalisation of the management of overweight or obese patients, in particular those at risk of developing comorbidities associated with excess weight.

Run by a multidisciplinary team (dietitians, metabolic disease and sleep specialists) and profiting from the constitution of an unprecedented collection of data in this field, this project offers the perspective of personalisation in the management of the overweight and obese as well as improving our understanding of the impact of weight loss on the overall health of patients and their quality of life.

A strength of this study is its size (N=10 000) and the long follow-up (5 years). The challenge is not only to evaluate the anthropometric parameters but also to identify the factors that can impact the success or failure of a weight-loss programme in the short, medium and long term. These factors can be medical (presence of comorbidities, anthropometric measurements), personal (family environment, personal situation, housing, motivation) or linked to quality of life. A more detailed understanding of these determinants would make it possible to better identify the profiles of patients entering a weight-loss programme of the same type as the one evaluated, and to identify how these profiles can change over time.

As an essential component in weight gain and loss, we chose to explore sleep from various different angles, thanks to a set of qualitative and quantitative evaluations (questionnaires, connected device, etc), allowing collection of both subjective and objective data. This multidimensional data collection will allow us to document sleep duration/privation, sleep quality, sleep disorders and patient sleep chronotype, providing extensive and complementary information on sleep behaviours and associated sleep disorders.

We aim to extensively document the participants profile in order to account for the maximum number of possible confounders in the evolution of cardiometabolic parameters with weight loss. To measure the evolution of OSAS, PWV and peripheral neuropathies on a routine basis, there are nowadays scientifically validated connected devices that are relatively easy to use in prospective cohorts. We chose to use these innovative tools in subgroups of participants to complete their cardiometabolic profile evaluation and analyse the evolution of less traditionally studied parameters.

One of the main limitations of this study is the absence of a control group made up of overweight or obese people who receive no advice or only general advice to loose weight, without any other specific intervention. Another limitation is the constraint that participation in this study requires, in particular, the completion of the 12 online questionnaires at the start of the intervention as well as the use of connected devices by the subgroups of participants concerned, even though the devices are provided for free. The observational nature of the study might also impact the rate of non-adherence to the study and the dropout rate during the study. Besides, while a preliminary statistical analysis took into account the RNPC Programme’s dropout rate, estimated at 25%, a significant underestimate of this figure could compromise the results of the study.

One of the main issues in the management of weight loss is to reduce the burden of comorbidities, in particular arterial hypertension, diabetes, dyslipidaemia, sleep apnoea syndrome, metabolic steatohepatitis, renal insufficiency and depressive syndromes. By reducing the burden of these comorbidities, a weight-loss programme should normally lead to a reduction or even the elimination of associated therapeutic treatments. This could be: (1) a modification of the drug management (which translates, either by a reduction in the dosage or the number of treatments prescribed for chronic pathologies or by a change of the molecule prescribed during time), (2) stoppage of treatment by a medical device, for example, continuous positive airway pressure.

Ethics and dissemination

The study protocol was approved by the French Ethics committee (Comité de Protection des Personnes) Sud-Est I of Saint-Etienne University Hospital Centre (SI number: 23.00174.000237), on February 6th, 2023. As an observational study without changes in standard patient care or management, potential participants are provided with information about the study. Those who do not object to the use of their data for the study are included, in accordance with French law and European General Data Protection Regulations (GDPR).

The study follows the ethical principles for medical research involving human subjects of the Declaration of Helsinki, adopted by the 18th General Assembly of the World Medical Association (World Medical Association, 1964), which were last revised at the association’s 64th General Assembly, in Fortaleza, Brazil, in October 2013. All participants provide signed written informed consent to participate. ClinicalTrials.gov Identifier: NCT05857319.

SCOOP-RNPC results will be disseminated to all study participants via the study internet site: https://scoop-rnpc.fr/ and via annual webinars. The authors will disseminate the results via conference presentations and peer-reviewed scientific research articles.

Ethics statements

Patient consent for publication

Acknowledgments

We thank Alison Foote, PhD (an independent medical writer based in Grenoble, France), for critically reading, suggesting revisions, and editing the manuscript.

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