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New clinical trial

BY-BAND trial hopes to impact UK surgery

Trial to examine gastric bypass surgery vs. gastric banding
Two primary outcome measure are better quality of life and weight loss
Results could have "enormous impact” on bariatric practice in the UK
Jane Blazeby

The chief investigator of a three-year trial, which plans to determine whether gastric bypass surgery leads to better quality of life and weight loss than gastric banding, is hopeful that the study will have an “enormous impact” on bariatric practice.

Professor Jane Blazeby, professor of surgery at the University of Bristol, said she hoped that if her study, named “Gastric BYpass or adjustable gastric BANDing surgery to treat morbid obesity” (BY-BAND; ISRCTN00786323), confirms its hypothesis when it publishes its results it would inform future NHS commissioning and potentially influence international bariatric practice.

The BY-BAND trial, has received more than £2.8m in funding from the National Institute for Health Research Health Technology Assessment Programme and will begin recruitment in April this year, plans to establish two points: firstly, whether bypass leads to better quality of life than banding, and secondly, whether it is at least as good as banding for weight loss. If both are met at three years after randomisation, then the investigators will conclude that bypass is the superior operation.

“If we can achieve what we hope to achieve – if we can really answer the question as to which operation is the most effective and cost-effective – it’s going to have an enormous impact,” said Blazeby. “It will put obesity surgery right up there on the political agenda.”

“We desperately need to know”

The investigators initiated the trial after observing a lack of good comparative evidence on the two procedures. “We desperately need to know which operation is better, because we need more operations that are cheaper,” said Blazeby. “We think that BY-BAND will provide those answers.”

A systematic literature review carried out by the investigators identified 26 randomised clinical trials comparing different bariatric procedures, only two of which directly compared gastric bypass to banding. They also found methodological issues in those that were carried out, making their randomisation questionable. 

In one well-known study, there were statistically significant differences in both the average age (41.4 ± 11 years vs 45.8 ± 9.8 years; p < 0.01) and average BMI (47.5 ± 5.5 vs 45.5 ± 5.4; p = 0.01) between the bypass and band cohorts, meaning that differences in outcome could be attributed to differences between the patient groups instead of the differences in operations. 

It also allowed patients to cross over between cohorts and did not subsequently undertake an intention to treat analysis, further compromising the trial’s randomisation. “At this point, there’s almost no point doing a long-term analysis,” said Blazeby of the study.

While non-randomised studies have produced a wealth of data, she said, the fact that patients were deliberately chosen for different operations means that differences between patients confounds any potential conclusions as to the two operations and their efficacy.

The lack of firm evidence as to the superior procedure has led to enormous variation in the type of operations carried out, with the decision often coming down to the surgeon’s preference. “There’s variation in the rates between centres in which the procedures are done,” said Blazeby “It’s not as if all surgeons know which one to select; there’s just this massive variation.” 


BY-BAND aims to randomise around 726 patients, into either the LAGB or RYGB cohorts. An initial pilot phase will take place at two hospitals in Taunton and Southampton; once this is complete, the trial will be extended to six further hospitals. The randomisation procedure, which will conceal the patients’ allocation from the investigators, will reduce the opportunity for selection bias.

The investigators decided to exclude sleeve gastrectomy from the trial as there is currently insufficient long and medium term data on its use, and because it currently only makes up around 10% of bariatric procedures in the UK. The fact that the surgical technique is still changing due to the procedure’s relative novelty also means that it is not suitable for a long-term comparative study.

Patients will be selected for BY-BAND if they are:

  • Over 18 years of age; 
  • Referred for bariatric surgery according to NICE guidelines;
  • Willing to receive intensive management in a specialist obesity service;
  • Fit for anaesthesia and surgery; they are committed to follow-up and able to complete quality of life questionnaires; and
  • Able to provide written informed consent.

Patients will be excluded if:

  • They have a history of gastric or obesity surgery;
  • They have a large abdominal ventral hernia;
  • They have a hiatus hernia more than 5cm;
  • They are pregnant;
  • They have Chron’s disease;
  • They have liver cirrhosis and portal hypertention;
  • They have systemic lupus erythematosis;
  • They have a known silicone allergy; or
  • If their surgeon is unwilling for the patient to be randomised.

The two primary outcome measures are quality of life, measured by their EQ-5D health state score at three years, and weight loss, measured by the proportion achieving loss of greater than 50% excess weight at three years. The investigators will also be studying a number of secondary outcomes, including time between 50% EWL and first relapse, resource use, nutritional blood tests, binge eating behaviour, adverse health events, and resolution of co-morbidities.

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