Persistent swelling (chronic oedema), e.g. of the legs, is quite a common condition, which can cause a number of problems, including infections (cellulitis) in the swollen area and ulceration. It seems to be particularly common in people who are overweight but this has not been studied in detail. This study aims to address this gap in knowledge. It will take place in two stages, running in parallel to each other with different groups of patients. The first stage will determine how common persistent swelling is among patients attending weight management services at the Royal Derby Hospital and how it impacts on every day life. The second stage will determine whether weight loss surgery improves the swelling.

The results will inform future treatment guidelines for overweight patients who have swelling. They will also inform the design of future research that will investigate the effects of weight loss surgery in more detail, for example by testing out methods of measuring fluid changes in the legs.

All new patients attending the weight loss service will be eligible to take part in the first stage of the study, as long as they: give their informed consent to take part, and can speak English (or have someone with them who speaks English). Participants will not have had weight loss surgery previously. The Stage 1 assessment is expected to take about 40 minutes and consists of: a single clinical assessment for each participant to identify the presence of the swelling and its degree in each of the affected areas and, up to 3 questionnaires concerning their quality of life and mobility.

Patients attending the programme, who have been referred for bariatric surgery, will take part in the second stage of the study. Stage 2 will last approximately 13 months, during which time the participants will be assessed 4 times - once before surgery and at 3, 6, and 12-month intervals after surgery. Each Stage 2 assessment is expected to take about 50 minutes and consists of: a clinical assessment and up to 5 questionnaires.

The clinical assessments included in both stages of the study will identify the presence and severity of swelling in each of the affected areas. Each assessment will consist of a clinical examination of the patient's legs and abdomen to look for swelling and changes in the skin associated with this.

Assessments carried out in Stage 1 will include bioimpedance and tissue dielectric constant (TDC) techniques.

• Bioimpedance measures the total fluid within a limb. This test passes an extremely small electrical current through the participant's body and measures the resistance to the flow of this current. The participant will not feel anything when the measurement is carried out as the current is very small, similar to the strength of a watch battery. If the participant is able to, the test will be undertaken with the participant lying down on an examination couch or sitting in a chair. Small stickers will be placed on the participant's hands and feet, and clips attached to these.
• The TDC measures fluid levels at different points. In order to record these fluid levels, a probe will be placed against the participants' skin on their feet, lower legs, and thighs.

Assessments carried out in Stage 2 will include bioimpedance, TDC, and also perometry (or measuring using a tape measure).

- This test measures the size and shape of the participants' legs, and can be undertaken by one of two methods depending on their mobility. If they need to stay in a chair or examination couch during the assessment, the size of their legs will be measured at different points using a tape measure. However, if possible, a device called a perometer will be used. Participants will be asked to stand with one leg in the frame of the perometer while it is moved up and down the leg. The frame contains lights which are used to measure the size and shape of the limb.

None of the assessments included in either stage should cause any pain or discomfort.

The questionnaires, which will be completed in both stages, concern the participants' quality of life and mobility.

• The EQ-5D questionnaire compares quality of life over time well and can assess the health utility of the participants. The EQ-5D scores can be used to calculate quality-adjusted life years.
• The GAD-7 (Generalised Anxiety Disorder 7-item Scale) and PHQ-9 (Patient Health Questionnaire - 9) questionnaires will be used to assess the anxiety/depression of the participants. Stage 1 participants will have completed these before their study assessments so the study team will obtain these results from their clinical records. Stage 2 participants will complete the questionnaires as part of the study assessments.
• The SF-36 questionnaire will assess the mobility of the participants and give general health-related quality of life scores.
• The LYMQOL questionnaire, which will only be given to participants who have oedema, is a validated, condition-specific, quality of life instrument. It can be used both: to assess lymphoedema of the limbs and as an outcome measure.

Inclusion Criteria:

• Adults who have capacity to give informed consent.
• Ability to understand the assessment questionnaires in English.

Stage 1 - all patients accepted for referral. There are no co-morbidities that would exclude people.

Stage 2 - patients that undergo bariatric surgery.

Exclusion Criteria:

- Patients under the lower age limit of 18.

Stage 2 - By-Band-Sleeve study participants who are taking part in the randomisation part of the study.

Stage 1 will assess patients attending the Tier 3 weight management programme at the Royal Derby Hospital, who are accepted for referral and provide informed consent to take part in the study.

Stage 2 will assess patients attending the Tier 4 programme who undergo bariatric surgery.

Individual participant data will be sent out after the study has ended to participants who request them.