Bariatric surgery reduces heart risk and diabetes

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Bariatric (weight-loss) surgery can reduce the risk of developing serious health conditions such as heart attacks and type 2 diabetes, as well improve existing conditions, according to a new study. The project is the largest comprehensive study of longer-term outcomes post bariatric surgery in the UK. It suggests that widening the availability of bariatric surgery could boost the health prospects for thousands of people who are very obese (body mass index/BMI of 40 kg/m2 or more).

The research was led by the London School of Hygiene & Tropical Medicine in partnership with University College London and the UCLH Bariatric Centre for Weight Management and Metabolic Surgery. Using primary care records, the researchers compared weight, BMI, and obesity-related illnesses between 3,882 bariatric surgery patients and similar control patients who did not have surgery, over an average period of three and a half years. They found that weight-loss surgery can significantly improve existing type 2 diabetes and reduce abnormally high blood pressure.

They also applied the findings to estimate that if the 1.4m people believed to be morbidly obese in the UK had bariatric surgery, it could prevent 80,000 cases of hypertension, 40,000 cases of type 2 diabetes, and 5,000 heart attacks over a four year period. Furthermore, 110,000 people with type 2 diabetes and 13,000 people with hypertension could significantly improve their condition.

Additionally, the study confirmed that the procedures stimulate dramatic and substantial weight loss which is sustained for at least four years, and suggested that gastric bypass and sleeve gastrectomy promote the most weight loss out of the different types of surgery.

Bariatric surgery is used to treat people who are very obese, for example, a woman of average height (162cm, 5 feet 5 inches), with type-2 diabetes and weighing 96 kg/15 stone, which equates to a BMI of 35. It is available on the NHS to treat people when other options, such as lifestyle changes, have not been successful.

Lead author Dr Ian Douglas, from the London School of Hygiene & Tropical Medicine, said: "Obesity is one of the biggest health problems of our generation. Rates of cardiovascular disease, although slowly declining, are still alarmingly high while type 2 diabetes is on the rise, affecting 3.5m people in Britain. Finding effective ways to tackle the obesity crisis is therefore a key public health strategy.

"Whilst effective prevention is clearly needed, our findings show that as well as helping patients substantially lose weight, bariatric surgery improves serious obesity-related illnesses as well as reducing the risk of developing them. People having weight-loss surgery were 70% less likely to have a heart attack, and those with type 2 diabetes were nine times more likely to see major improvements in their diabetes. We also found positive effects on angina and the debilitating condition obstructive sleep apnoea."

The study also indicated which type of surgery might be most effective for losing weight. Estimated average four year weight loss was 38 kg/six stone for gastric bypass, 31 kg/five stone for sleeve gastrectomy, and 20 kg/three stone for gastric band.

Study co-author Professor Rachel Batterham, head of the UCLH Bariatric Centre for Weight Management and Metabolic Surgery and the UCL Centre for Obesity Research, said: "Bariatric surgery is safe and produces unrivalled health benefits that are life-changing for patients and cost-saving for the NHS. Unfortunately, less than 1% of the patients who could benefit from this surgery currently receive surgery. This represents a major missed opportunity in terms of improving health and economic savings. Action is now needed to remedy this situation."

The researchers note that the accuracy of these findings may be limited by the incomplete recording of some outcomes in primary care patient management records. They were also unable to look in detail at short-term adverse outcomes associated with bariatric surgery, but noted that nationally collected data suggests such complications are rare.

Abstract
Background
Bariatric surgery is becoming a more widespread treatment for obesity. Comprehensive evidence of the long-term effects of contemporary surgery on a broad range of clinical outcomes in large populations treated in routine clinical practice is lacking. The objective of this study was to measure the association between bariatric surgery, weight, body mass index, and obesity-related co-morbidities.
Methods and Findings
This was an observational retrospective cohort study using data from the United Kingdom Clinical Practice Research Datalink. All 3,882 patients registered in the database and with bariatric surgery on or before 31 December 2014 were included and matched by propensity score to 3,882 obese patients without surgery. The main outcome measures were change in weight and body mass index over 4 y; incident diagnoses of type 2 diabetes mellitus (T2DM), hypertension, angina, myocardial infarction (MI), stroke, fractures, obstructive sleep apnoea, and cancer; mortality; and resolution of hypertension and T2DM. Weight measures were available for 3,847 patients between 1 and 4 mo, 2,884 patients between 5 and 12 mo, and 2,258 patients between 13 and 48 mo post-procedure. Bariatric surgery patients exhibited rapid weight loss for the first four postoperative months, at a rate of 4.98 kg/mo (95% CI 4.88–5.08). Slower weight loss was sustained to the end of 4 y. Gastric bypass (6.56 kg/mo) and sleeve gastrectomy (6.29 kg/mo) were associated with greater initial weight reduction than gastric banding (2.77 kg/mo). Protective hazard ratios (HRs) were detected for bariatric surgery for incident T2DM, 0.68 (95% CI 0.55–0.83); hypertension, 0.35 (95% CI 0.27–0.45); angina, 0.59 (95% CI 0.40–0.87);MI, 0.28 (95% CI 0.10–0.74); and obstructive sleep apnoea, 0.55 (95% CI 0.40–0.87). Strong associations were found between bariatric surgery and the resolution of T2DM, with a HR of 9.29 (95% CI 6.84–12.62), and between bariatric surgery and the resolution of hypertension, with a HR of 5.64 (95% CI 2.65–11.99). No association was detected between bariatric surgery and fractures, cancer, or stroke. Effect estimates for mortality found no protective association with bariatric surgery overall, with a HR of 0.97 (95% CI 0.66–1.43). The data used were recorded for the management of patients in primary care and may be subject to inaccuracy, which would tend to lead to underestimates of true relative effect sizes.
Conclusions
Bariatric surgery as delivered in the UK healthcare system is associated with dramatic weight loss, sustained at least 4 y after surgery. This weight loss is accompanied by substantial improvements in pre-existing T2DM and hypertension, as well as a reduced risk of incident T2DM, hypertension, angina, MI, and obstructive sleep apnoea. Widening the availability of bariatric surgery could lead to substantial health benefits for many people who are morbidly obese.

London School of Hygiene & Tropical Medicine material PLOS Medicine abstract

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