Bariatric surgery is safe and induces substantial weight loss that reduces the need for diabetes medications, a Monash University and University of Sydney-led Australian study has found.
Published in the ANZ Journal of Surgery, the study used data collected from people who had bariatric surgery in Australia from 28 February 2012 until 31 December 2021. The 122,567 patients underwent a total of 134,625 completed bariatric procedures.
Five years post-surgery, those who underwent one-anastomosis gastric bypass had total body weight loss of 34.88 per cent, those who underwent roux-en-Y gastric bypass lost 30.73 per cent, those who had sleeve gastrectomy lost 26.5 per cent and those with adjustable gastric bands lost 17.6 per cent.
Of the participants, 13.6 per cent reported being treated for diabetes before surgery. Of the 58 per cent of those followed up, 71.6 per cent required no diabetes medication after 12 months. For the 22 per cent who were followed up after five years, the figure was 61 per cent.
Ninety days post-surgery, 3.6 per cent of patients had experienced adverse events such as unplanned readmission, intensive care admission, re-operation or death. This meant the surgery was considered safe, with similar adverse event rates to other keyhole surgery such as gallbladder removal.
First author and Chair of Monash University's Department of Surgery, School of Translational Medicine at Alfred Health, Professor Wendy Brown, said this was the first community-level data showing that bariatric surgery was safe, confirming findings from single centres and other trials.
"This should reassure patients, their loved ones and payers such as government and insurers that bariatric surgery is safe, effective and delivers great health improvement," Professor Brown said. "It will also help to inform more accurate patient consent, so patients have an idea of what they can realistically expect to achieve after an operation and what the risks are.
"This is the first time that it has been shown that the positive effects of bariatric surgery can be delivered in the general community, not just at expert centres, and the first time that the results have been shown to be durable at five years at a community level.
"The ability to have 61 per cent of people who were being treated for diabetes at the time of their bariatric surgery come off all medications at five years is a major benefit, not just for the individual, but also for our community in terms of health care expenditure."
Professor Brown said when assessing the suitability of someone living with obesity for bariatric surgery, she considered where excess fatty tissue was impacting their health, their quality of life and sense of wellbeing.
She said the low adverse event rate was "extraordinary" as obesity was traditionally considered a risk factor for anaesthetic and other surgery complications.
"The safety of bariatric surgery is reassuring as it means we can safely offer people a way to lose and keep off a substantial amount of weight, offering an opportunity to reverse or improve many health problems," she said. "Usually they will have tried other ways of losing weight prior to being offered surgery."
The longitudinal registry-based observation study used data from the Australia and New Zealand Bariatric Surgery Registry, which curates national data on the safety of bariatric surgery, weight loss and health improvement, using diabetes medication change as a measure of health. The pilot study began in 2012, with national rollout in Australia starting in 2014 and in Aoteoroa New Zealand in 2018. This report analysed outcomes from the first 122,567 participants who completed bariatric procedures and were enrolled in the registry's Australian arm.
Of these, 79 per cent were female and the mean age on the day of surgery was 44. The mean BMI was 41.7.
The research team now hopes to analyse revisional surgery, patterns of care and outcomes in people living with both obesity and diabetes in more detail. "Patient reported outcomes will also be included in the registry from 2025, further strengthening reporting," the researchers said.
A case study with lived experience of bariatric surgery is available to talk to the media.
About the Australia and New Zealand Bariatric Surgery Registry (BSR)
The BSR is a longitudinal community level national registry that aims to prospectively collect identifiable information from all people undergoing a primary or revisional metabolic bariatric surgical procedure in Australia, excluding endoscopic procedures performed with the intention of being reversed within a year. The most common primary procedure is Sleeve Gastrectomy (80 per cent) and the most common revisional conversion procedure was Roux-en-Y Gastric Bypass (21.8 per cent).
