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UK bariatric surgery – confirmed clinical outcome benefits

Bariatric surgery as delivered in the UK healthcare system is associated with dramatic weight loss, and benefits in cardiometabolic co-morbidities, according to a recent study conducted by workers from the London School of Hygiene and University College London.1 Widening the availability of bariatric surgery could lead to substantial health benefits for many people who are morbidly obese, the invesitgators conclude.

The weight loss, which is sustained at least four years after surgery, is accompanied by substantial improvements in pre-existing type 2 diabetes (T2DM) and hypertension, as well as a reduced risk of incident T2DM, hypertension, angina, myocardial infarction, and obstructive sleep apnoea.

The researchers used the UK Clinical Practice Research Datalink (UKCPRD), which contains anonymised clinical information about patients provided by general practitioners, to identify 3,882 patients who had had bariatric surgery.

They matched each patient (average BMI 44.7 kg/m2), according to the patient’s medications and constellation of risk factors, to an obese individual from the dataset who had not had bariatric surgery. This “propensity matching” technique is used in studies where patients are not allocated at random to receive a treatment, and is meant to control for confounding – the possibility that patients who receive the treatment may be otherwise distinct from patients who do not.

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Professor Rachel Batterham (University College London)

According to this analysis, patients who had had bariatric surgery lost weight rapidly during the first four post-operative months (4.98 kg/month); their weight loss was sustained at a slower rate for up to four years. By contrast, there were no weight changes in the patients who did not have surgery.

While bariatric surgery was associated with health benefits, over an average of 3.4 years of follow-up, there was no evidence of any difference in the risk of death.

BJC Arrhythmia Watch Interviewed one of the study authors, Professor Rachel Batterham, Head of UCLH Obesity & Bariatric Services and Head of the Centre for Obesity Research, Department of Medicine, University College London.

What is the most acceptable working hypothesis on why significant weight loss is independently associated with CHD benefits in obese patients.

“We didn’t actually show that it is independently associated with reduced risk. What we’ve shown is that people who have surgery lose weight and they also have lower CHD risk. We haven’t looked at whether people who lose more weight have a better CHD prognosis than people who lose less weight”.

What sort of observation period would be needed to possibly show an overall mortality benefit with this surgery?

“It’s possible the benefit is seen quite early, e.g. after the first year. Our data suggest this is possible, with an average follow up of 3.4 years, but we’d need a bigger sample of surgery patients, rather than a longer period to confirm this”.

What is the main clinical message from the results of the study e.g, should we encourage more referrals for this surgery in high risk groups?

“Surgery as delivered in routine clinical care in the UK is leading to both dramatic weight loss and major health benefits, particularly with respect to type 2 diabetes and cardiovascular disease. Bearing in mind the statistics for obesity in the UK there is very little surgery currently being performed, mostly due to a lack of referral and funding for people who are already deemed eligible according to nice guidance. Our results suggest there are major savings to be made by making surgery more accessible; not just in terms of financial cost, but also a reduction in disease burden for individual patients”.

Does your study show particular benefits for certain types of bariatric intervention e.g. bands versus sleeve procedures.

“Our results suggest weight loss may be greatest with gastric bypass than other types of surgery. Both gastric bypass and sleeve gastrectomy performed better than gastric band in terms of both weight loss and resolution of type 2 diabetes and hypertension”.

Are such interventions cost-effective in terms of QALYs and is there sufficient access (availability) for this surgery in the UK?

“We were unable to directly calculate the long term costs associated with treating or not treating people with bariatric surgery. But we do know from work that others have done in the UK that surgery is cost effective: there are large costs associated with treating type 2 diabetes and cardiovascular disease, which are likely to be offset relatively soon after surgery, given the beneficial effects we’ve seen on these 2 diseases alone”.

Forthcoming clinical meeting

The first UK national symposium focusing on the management of medical problems relating to severe and complex obesity, will be held at Nottingham Belfry Hotel of 26th April 2016.

Created in association with The East-Midlands Bariatric & Metabolic Institute (EMBMI) presentations will be from experts across multiple specialties in the field, including General Practice, Endocrinology, Respiratory, Hepatology, Cardiology and Gynaecology.

The meeting has been designed to appeal to GPs, nurses, commissioners and specialist obesity physicians.

Further details from:


1. Douglas IJ, Bhaskaran K, Batterham RL, Smeeth L. Bariatric surgery in the United Kingdom: a cohort study of weight loss and clinical outcomes in routine clinical care. PLoS Med 2015;12:e1001925.

Published on: January 14, 2016

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