Obesity surgery ‘halves risk of death’ compared to lifestyle changes alone

Latest study of long-term impact of bariatric surgery lends support to experts who say more operations should be carried out in UK

Bariatric surgery reduces the size of the patient’s stomach. It is cost-effective and leads to substantial weight-loss as well as helping to tackle type 2 diabetes.


Bariatric surgery reduces the size of the patient’s stomach. It is cost-effective and leads to substantial weight-loss as well as helping to tackle type 2 diabetes. Photograph: Murdo Macleod for the Guardian

Obese patients undergoing stomach-shrinking surgery have half the risk of death in the years that follow compared with those tackling their weight through diet and behaviour alone, new research suggests.

Experts say obesity surgery is cost-effective, leads to substantial weight loss and can help tackle type 2 diabetes. But surgeons say not enough of the stomach-shrinking surgeries are carried out in the UK, with figures currently lagging behind other European countries, including France and Belgium – despite the latter having a smaller population.

“We don’t think this [new study] alone is sufficient to conclude that obese patients should push for bariatric surgery, but this additional information certainly seems to provide additional support,” said Philip Greenland, co-author of the latest study from Northwestern University.

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In the new study, one of several on obesity surgery published in the Journal of the American Medical Association, researchers sought to explore whether stomach-shrinking operations, known as bariatric surgery, had a long-term impact on the risk of death among obese individuals, compared with non-surgical approaches to weight loss.

In total, more than 33,500 participants were involved in the study – 8,385 of whom had one of three types of bariatric surgery between 2005 and 2014. The majority of participants had a BMI greater than 35; obesity is defined as a BMI of 30 or higher.

The researchers followed up the participants over the years that followed their surgery until death, or the end of the follow-up period in December 2015, comparing the number of deaths and other metrics with those for obese patients who had not had surgery but were given dietary and behavioural help. Each surgery patient was compared to three who did not have surgery, but had similar characteristics such as age and sex, and were also followed until they too had surgery, died or the study ended.

The results reveal that the death rate during the study was 1.3% for those who had any form of bariatric surgery, while among those who had not had surgery it was 2.3%, although the length of follow-up period varied considerably from patient to patient.

Once other factors including age, sex and related diseases were taken into account, the team found those who did not have stomach-shrinking surgery had just over twice the risk of death compared to those who had, with all three types of surgery linked to lower mortality.

What’s more, the group which had surgery showed a greater reduction in BMI, lower rates of new diabetes diagnoses, improved blood pressure, and a greater proportion of diabetic individuals going into remission.

But the team add that a small proportion of surgery patients required further surgery, while they note the study was observational so cannot prove bariatric surgery itself reduced the risk of death since patients were not randomised, meaning it is possible that those who did not have surgery were in poorer health.

A second, smaller study in the same journal also highlighted benefits of bariatric surgery, comparing diabetes-related markers in obese adults who had lived with a diagnosis of type 2 diabetes for an average of nine years. Participants either received two years of intensive diet, exercise and medical management or, in addition, had bariatric surgery.

The results from 113 participants reveal that complications were more common among those who had had bariatric surgery, but that one year after the study began they had lost more weight on average, with a greater proportion having reached the combined targets for cholesterol, systolic blood pressure and a marker of glucose.

While this proportion fell for both groups after five years – at which point 98 patients were still providing data – those who had had bariatric surgery maintained the edge, with 23% reaching the combined targets, compared to just 4% of those offered lifestyle and medical interventions alone.

Francesco Rubino, professor of metabolic and bariatric surgery at King’s College London, who was not involved in the studies, said misunderstandings and stigma were holding back greater use of such operations in the UK. While Rubino noted that surgery is not for everyone, he added “This is a conversation GPs and doctors should have with patients more often.”

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