Previous clinical trials have suggested that bariatric surgery is effective for producing clinically significant weight loss in patients with a BMI of 40 or higher.

However, surgical intervention is not without risk: the 30-day mortality rate following gastric bypass surgery has been reported to be 0-2%, and this figure may be much higher in certain patient groups, such as older patients or those with co-morbid conditions.

For this latest study published in Archives of Surgery, University of Cincinnati researchers used a computer model to evaluate the benefits and risks of gastric bypass surgery for obese individuals, with a view to optimising patient selection for surgery. The model used data from over 400,000 patients.

The researchers found that an average 42-year-old woman with a BMI of 45 would gain an additional three years of life following surgery. A 44-year old man with the same BMI would live an additional 2.6 years.

The benefits of surgery were particularly high for younger patients. ‘Younger patients have lower surgical risk and more time over which to realise the benefits of surgery,' the authors wrote. ‘For older patients, the gain is smaller, and for some, gastric bypass surgery will decrease life expectancy.'

‘While not all patients are guaranteed a good outcome, our model indicates that gastric bypass increases life expectancy for most patient subgroups,' the researchers concluded. ‘However, for those at high surgical risk or in whom efficacy of surgery is likely to be low, benefit will be minimal.'

The researchers believe that the results of this analysis could be used to inform decisions about whether to opt for gastric bypass surgery.