Study Overview

How the study works

The By-Band-Sleeve Study is currently in follow-up at twelve hospitals: Royal Bournemouth and Christchurch Hospitals, St James University Hospital, Leeds, University Hospital Southampton, Sunderland Royal Hospital, Musgrove Park Hospital, Taunton, Royal Cornwall Hospital, Truro, Heartlands Hospital, Birmingham, Queen Alexandra Hospital, Portsmouth, Royal Derby Hospital, Derby, Homerton Hospital, London, St Mary’s Hospital Imperial College, London and Southmead Hospital, Bristol.

Adults who were referred for bariatric surgery at any of these hospitals were able to take part in the study. Patients were given some information to read about the study and the chance to discuss it with the health professionals on the team. Those who agreed to take part had an equal chance of being assigned a gastric band, a gastric bypass, or a gastric sleeve. This allows the three types of operations to be compared in a balanced way. Participants were told which operation they had been assigned to several weeks before their actual operation date. In September 2019 the study recruited to target, randomising 1341 patients.

After surgery, participants will be followed up carefully, including regular weight checks. They will be asked to complete questionnaires about their quality of life and use of healthcare. Some participants will also be interviewed about their experience. Researchers will also ask participants to provide two blood samples for future research into obesity, in addition to the samples people would give as part of their normal care. All participants will be followed up by the study team for three years.
The study is coordinated from the Bristol Trials Centre (formerly the Clinical Trials and Evaluation Centre) at the University of Bristol and involves a team of experts, including researchers from the Universities of Bristol, Birmingham, Oxford, and Southampton, and health professionals from each of the study hospitals. The study started in 2012 and will end when the final patient has completed follow up and all data has been analysed. The study is funded by the National Institute for Health Research Health Technology Assessment Programme (ref: 09/127/53).


The By-Band-Sleeve study is aiming to compare the three different types of operations to find out which is most effective. The results of this study will be used to improve the information available to people considering bariatric surgery in the future, which will help with decision-making between health professionals and patients. The results will also be used to inform NHS commissioners about the most effective and cost-effective operation.

Study Status

The By Band Sleeve study team were pleased to reach their target recruitment of 1341 patients in September 2019. Currently not all participants have had their surgery, but we are closely monitoring all patients as they move through the study. The study is now in a phase of follow-up and data gathering will continue until the very last patient completes their final follow up appointment.