In this community-based study, the research team studied the records of patients treated between 1990 and 2003. Those records included 197 patients with advanced degrees of obesity (body mass index (BMI) of 40 and above, or BMI above 35 with multiple cardiac risks) who underwent Roux-en-Y (pronounced ROO-en-Y) bypass surgery, the most common weight-reduction surgery in the United States. The control group included 163 patients enrolled in a weight-reduction program. With an average follow-up time of 3.3 years, the researchers recorded changes in cardiovascular risk factors such as blood pressure, diabetes indicators, cholesterol levels and BMIs.
Researchers were surprised by the findings, says John Batsis, M.D., lead author of the study. The researchers' estimated 10-year risk for death or cardiovascular events, such as a heart attack, in the surgical group decreased from 37 percent to 18 percent as a result of the study but remained the same for the control group (30 percent), he says.
"We believed the surgical patients would have a modest reduced risk, but instead we discovered there are significant and long-lasting heart benefits for this group," Dr. Batsis says.
When data from both groups was compared, those who underwent bariatric surgery had a more significant improvement in all cardiac risk parameters, such as body weight, lipid levels, systolic and diastolic blood pressure and fasting glucose levels, despite a reduction in medications for diabetes, high blood pressure and high cholesterol, Dr. Batsis says.
Applying the finding about change in risk factors, the authors calculated the 10-year risk for death or cardiovascular events using risk models derived from the National Health and Nutrition Surveys. The researchers estimated that for every 100 patients, the surgery likely would prevent 16 cardiovascular events and 4 overall deaths, as compared with the control group. This study was based on outcomes at Mayo Clinic, which performs a large volume of bariatric surgeries and has a very low peri-operative mortality rate.
Previous studies have assessed the effect of bariatric surgery on heart disease risk factors, but this is the first community-based study with a control group, a long-term follow-up for this patient population, and includes only Roux-en-Y surgery. This is also the first study estimating the risk reduction for death or heart complications.
Francisco Lopez-Jimenez, M.D., a cardiologist at Mayo Clinic and senior author of this project, believes this study has major public health implications because it approaches two epidemics: obesity and heart disease. "This study proves that major weight loss is followed by an impressive reduction in risk factors for heart disease and a significant reduction in the use of medications for diabetes, cholesterol and blood pressure," he says.
Co-authors of the paper are Abel Romero-Corral, M.D.; Maria L. Collazo-Clavell, M.D.; Michael G. Sarr, M.D.; Virend Somers, M.D., Ph.D., all of Mayo Clinic, Rochester, Minn.; and Lee Brekke, Ph.D., of Brekke Associates, Minneapolis.
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