Obesity and diabetes mellitus are two conditions that are constantly growing all over the world and are associated with a significant increase in morbidity and mortality. Both are often present in the same subject and are generally quite difficult to control with diet and drugs.
In selected patients, bariatric surgery techniques can be employed. Modifying the normal path of food within the gastrointestinal system they have been shown to be effective in treating obesity, reducing morbidity and improving the quality of life of severely obese patients.
A recent study, published in the journal JAMA, appears to reinforce the role of bariatric surgery, highlighting how it can also reduce major cardiovascular events in patients with type 2 diabetes and obesity.
Bariatric surgery began in the 1950s with the first intestinal bypass and then progressed, with vertical band gastroplasty and gastric bypass.
With the development of less invasive, laparoscopic surgery techniques, bariatric surgery has further developed leading to a growing demand for these procedures.
According to a survey by the International Federation for the Surgery of Obesity and Metabolic Disorders (IFSO), bariatric surgery has grown over 10 times worldwide over the past 20 years, with an increase from 40,000 procedures in 1997 to over 460,000 in 2013.
Due to the high incidence of obesity, the bariatric procedure has become the most commonly performed surgical procedure in the United States.
With its development, bariatric surgery has become increasingly safer. Recent data indicate a 30-day mortality of 0.012%.
Bariatric surgery techniques are varied and continue to evolve over time. In general, they can block the absorption of food, reducing the size of the stomach, but they can simply be restrictive, inducing a greater sense of satiety after a meal. Finally, there are mixed techniques, when these procedures coexist.
Over the time, intestinal bypass and vertical gastric band have been abandoned. Even the adjustable laparoscopic gastric band is less frequently performed.
In contrast, since 2014 laparoscopic sleeve gastrectomy has become the leading bariatric procedure in the United States. According to IFSO statistics, the most commonly performed procedure in the world in 2011 was the Roux-en-Y gastric bypass.
It is a simple observational study, with all the limitations connected with study design, but its results are very interesting. The researchers started from the assumption that there are well-defined data on the improvements induced by bariatric surgery on cardiometabolic risk factors, but its effectiveness in preventing cardiovascular events has not yet been clarified.
For this reason, they wanted to analyze the data of over 280,000 patients with type 2 diabetes, selecting among these 2,287 subjects (median age 52 years; BMI 45,1) who had undergone bariatric surgery.
They were paired to a control group consisting of 11.435 non-surgical patients with type 2 diabetes and obesity (median age 55 years; BMI 42.6).
The main outcome of the study was the incidence of major cardiovascular events: all-cause mortality, coronary events, cerebrovascular events, heart failure, nephropathy and atrial fibrillation.
The effects of bariatric surgery
At the end of follow-up period, the composite primary endpoint occurred in 385 patients in the surgical group and in 3,243 patients of the non-surgical group, with an incidence of 30.8% and 47.7% respectively (HR 0.61).
The analysis of the interactions with the confounding variables did not reveal heterogeneity induced by age, body mass index, HbA1c level, estimated glomerular filtration rate or use of insulin, sulfonylureas or lipid-lowering drugs.
In particular, all-cause mortality occurred with a 10% cumulative incidence in surgical patients and in 17.8% of patients included in the control group (HR 0.59).
Despite the limitations associated with the observational design of the study, the results obtained seem to be in favor of bariatric surgery compared to conventional treatments, in preventing the main cardiovascular events in obese patients with type 2 diabetes.
It should be emphasized that this study also showed that patients who underwent surgery subsequently required fewer drugs to treat diabetes and cardiovascular disease, such us insulin, oral antidiabetic agents, renin-angiotensin system inhibitors and other antihypertensive and lipid-lowering drugs.
The authors conclude hoping that their results will be confirmed in randomized clinical trials.
Ali Aminian, et al. Association of Metabolic Surgery with Major Adverse Cardiovascular Outcomes in Patients With Type 2 Diabetes and Obesity. JAMA. , 2019; 322 (13): 1271-1282.