In 2025, bariatric surgery combined with nutritional and psychological support is one of the most effective treatments for patients with morbid obesity. (2)(3)

However, it causes various deficiencies, such as vitamin and iron deficiencies, which justify lifelong personalised vitamin supplementation and, consequently, lifelong medical supervision. The latest recommendations from the French National Authority for Health (Haute Autorité de Santé) clearly state that patients must commit to lifelong medical follow-up after bariatric surgery. (HAS, February 2024, R94). R94. Regular biological monitoring after bariatric surgery is recommended: three times in the first year and then once or twice a year thereafter.

Within the OBESEPI cohort (clinical trial number NCT02663388), which comprises patients who underwent surgery at Nancy University Hospital between 2013 and 2018, we observed that over 50% of patients were lost to follow-up five years after surgery.

Duration of the inclusion period: 3 months Duration of subject participation (from inclusion to the last visit for the same subject): 30 minutes (time required to complete the questionnaire) Total duration of the research: 9 months

Patients with obesity who met the HAS (French high health authority) criteria for surgical treatment were recruited.

This corresponds to patients with a BMI > 35 kg/m2 with obesity-related complications (hypertension and/or diabetes and/or dyslipidemia and/or obstructive apnea syndrom ) and patients with a BMI > 40 with or without obesity-related complications.

These patients, who were candidates for scheduled bariatric surgery, were recruited by a surgeon involved in the protocol during preoperative consultations in the Metabolic, Visceral and oncologic department of surgery ; Department at Nancy University Hospital; between 2013 and 2018 (the OBESEPI-ALDEPI cohort - clinical trial NCT02663388) ). All patients met the HAS's eligibility criteria previously cited for bariatric surgery.

Two groups could be studied:

Patients who underwent surgery and were lost to follow-up five years after after bariatric surgery

The second group comprised patients who underwent surgery and were still being monitored at Nancy University Hospital five years after their inclusion.

Patients were considered lost to follow-up if there was no record of them visiting the Metabolic, Visceral and oncologic department of surgery five years after their inclusion, as determined using the DXCare software (which contain medical file).

A questionnaire is used to collect all data. This is completed by telephone or sent by email to patients who have been lost to follow-up.

This questionnaire contains questions designed to help us achieve the main and secondary objectives described in the dedicated section.

Statistical analysis :

All data will be presented as numbers and percentages for qualitative variables, and as means, standard deviations, medians, quartiles, and extreme values for quantitative variables.

The characteristics of patients lost to follow-up from the OBESPI cohort will be compared with those still being followed up using Fisher's exact test, Chi-squared test or Wilcoxon's rank sum test.

To meet the objectives, these tests will also be used to compare patients lost to follow-up with those still being followed.

Assessment of research benefits:

Methods for monitoring patients lost to follow-up should be assessed in order to develop training for general practitioners in the Lorraine region, enabling them to provide appropriate follow-up care to patients who have undergone bariatric surgery.

Train general practitioners to prevent nutritional complications of bariatric surgery.

Train general practitioners to recognise the warning signs that require referral to a specialist centre.

There is major interest in improving healthcare practices, given that 60,000 bariatric surgeries are performed annually in France, with 800,000 patients having undergone surgery in 2019.

Inclusion Criteria:

• > Patients included in the OBESEPI cohort;

  • Individuals who have received complete information about the organisation of the research and have not objected to their participation and the use of their data;
  • Affiliation with a social security scheme.

Exclusion Criteria:

• >Patient who objects to participating in this research;

  • Pregnant and breastfeeding women;
  • Patients under legal guardianship or curatorship;
  • Patients deprived of their liberty by a judicial or administrative decision.

These patients were obese with BMI> 35kg/m2. These patients, who were candidates for scheduled bariatric surgery, were recruited during preoperative consultations by surgeons involved in the protocol at the Digestive, Hepatobiliary, Endocrine and Oncology Surgery Department at Nancy University Hospital between 2013 and 2018 (the OBESEPI cohort).