Bariatric surgery appears to cut risks for serious asthma-related events

A study led by Massachusetts General Hospital (MGH) investigators suggests that bariatric surgery can significantly reduce the risk of asthma attacks - also called exacerbations - in obese patients with asthma. Their report, published online in the Journal of Allergy and Clinical Immunology, is the first to find that significant weight reduction can reduce serious asthma-associated events.

“We found that, in obese patients with asthma, the risk of emergency department visits and hospitalizations for asthma exacerbations decreased by half in the two years after bariatric surgery,” says Kohei Hasegawa, MD, MPH, MGH Department of Emergency Medicine, the lead author of the study. “Although previous studies of non-surgical weight loss interventions failed to show consistent results regarding asthma risks, our result strongly suggests that the kind of significant weight loss that often results from bariatric surgery can reduce adverse asthma events.”

Both obesity and asthma are serious public health problems at historically high levels in the U.S., the authors note, and many researchers have associated obesity with the development of asthma and with an increased risk for asthma exacerbations. While previous studies investigating whether weight loss could reduce asthma risks showed little or no benefit, participants in those studies lost only modest amounts of weight. The current study was designed to investigate whether bariatric surgery - regarded as the most effective option for morbidly obese patients - might have a greater effect on asthma-associated risks.

Using available databases reflecting the utilization of health services in California, Florida and Nebraska - all three of which give access to deidentified information on individual patients - the research team identified 2,261 obese patients with asthma who underwent bariatric surgery from 2007 to 2009 and for whom information covering the two years before and after their surgery was available.

This design, in which participants essentially act as their own controls, reduces the need to control for additional factors - such as age, gender, genetic background and physical activity - that might bias the results.

The analysis showed that, during the two years prior to surgery, around 22 percent of the studied patients had at least one emergency department (ED) visit or hospitalization in each one-year period. In the two years after surgery, only 11 percent needed an ED visit or hospital admission in each year. Looking at hospitalization alone showed an even greater risk reduction, from around 7 percent per year to less than 3 percent. A comparison with patients who had other types of abdominal surgery showed that non-bariatric procedures had no impact on asthma exacerbation risk.

Asthma and Obesity
Obesity is on the rise in the United States. It’s well known that obesity can cause diabetes and heart disease, but studies show that it also leads to higher rates of asthma. Asthma is already a very common disease, but obese people are at an even higher risk. In Michigan, 13% of obese adults say they have asthma, but only 8% of non-obese adults say they have asthma.

Just how common is obesity in Michigan? In 2009, 30% of Michigan adults were obese and 12% of children were obese. More Michiganders are now obese than 10 years ago. Obesity is defined as having a Body Mass Index (BMI) of 30 or greater. Overweight is defined as a BMI of 25-29. Follow these links to calculate your BMI for children and adults.

Asthma and Obesity
The link between asthma and obesity has been shown in many studies. Asthma is a complex disease and there may be many reasons that it is linked with obesity. Asthma is affected by our behavior as well as our genes. One thing seems certain about the link: having asthma does not mean you are more likely to become obese.

Obesity causes chronic inflammation throughout the body, including the lungs. Asthma is caused by inflammation in the lungs. Inflammation from obesity can cause problems in the rest of the body as well.

Eating an unhealthy diet may make asthma and obesity worse. Even a mother’s poor diet during pregnancy can increase her child’s risk of asthma. Eating processed food high in calories and fats may add to obesity and asthma. It’s important to eat plenty of fruit, vegetables, and fish because they can help prevent asthma and obesity. Studies have shown that adults who eat more fruit are less likely to have asthma symptoms. Even if you are not obese, eating right is important for all people with asthma. Our bodies need vitamins, minerals, and antioxidants to help lungs stay healthy.

Experts also think that a lack of physical activity linked with obesity may make asthma worse. Exercise stretches muscle in the lungs and may help protect against asthma. Getting regular exercise is one of the best things you can do to improve lung health. It has even more benefits if you are obese.

One theory is that some of the genes that lead to obesity also lead to asthma. Some people’s DNA may make them more likely to be obese and more likely to have asthma. Since DNA can’t be changed, doctors advise trying to live as healthy as possible with asthma and obesity.

Bariatric surgery appears to cut risks for serious asthma-related events While the mechanism by which a significant weight loss can reduce asthma-associated risks is unknown, studies have linked obesity to increased inflammation, higher prevalence of gastroesophageal reflux disease, and physical changes in the airway - all of which could contribute to asthma severity. Hasegawa notes that a reduction or reversal of these mechanisms by bariatric surgery is plausible.

“The databases we had access to did not include the actual amount of weight lost by these patients, but it is well documented that bariatric surgery results in substantial weight loss, averaging around 35 percent of presurgical weight,” he says. “While we can’t currently say how much weight loss would be needed to reduce asthma risks, previous studies of non-surgical interventions indicate that modest weight loss is not enough.”

“Bariatric surgery is a costly procedure that carries its own risks, factors that may offset the benefits regarding the risk of asthma exacerbation for some patients,” Hasegawa adds. “To decrease asthma-related adverse events in the millions of obese individuals with asthma, we probably will need to develop safe, effective non-surgical approaches to achieve major weight loss.”

Overweight and obese kids are more likely to struggle with asthma than kids of normal weight, according to a new review of more than 623,000 children.

Researchers found that children carrying extra weight are between 1.16 to 1.37 times more likely to develop asthma than normal-weight kids, with the risk growing as their body-mass index—a measure of body fat encompassing height and weight—increases.

Obese children also experience more frequent and severe episodes of asthma, requiring more medical attention and drug therapy, found the study in the Aug. 7 issue of the American Journal of Epidemiology.

For example, heavier kids required more visits to the doctor to treat their asthma, and needed to use inhalers more often to help restore normal breathing.

Inflammation caused by body fat is suspected to be one factor in the kids’ increased risk of asthma, said study lead author Mary Helen Black, of the department of research and evaluation at Kaiser Permanente Southern California.

The extra pounds also might affect the severity of asthma by placing additional weight on a child’s chest, Black said.

Overweight and obese youths have greater perceived symptoms of asthma,” she said. “When they have difficulty breathing, it seems more extreme to them than to kids with normal weight.” This could be due to the added weight constricting their breathing.

Asthma is the most common chronic childhood illness in the United States, affecting one of every 10 kids, according to study background information.


Hasegawa is an assistant professor of Emergency Medicine at Harvard Medical School. Additional co-authors of the Journal of Allergy and Clinical Immunology paper are senior author Carlos Camargo, MD, DrPH, MGH Emergency Medicine; Yuchiao Chang, PhD, MGH Department of Medicine; and Yusuke Tsugawa, MD, MPH, Harvard Interfaculty Initiative in Health Policy. The study was supported in part by an Eleanor and Miles Shore Fellowship grant from Harvard Medical School.

Massachusetts General Hospital , founded in 1811, is the original and largest teaching hospital of Harvard Medical School. The MGH conducts the largest hospital-based research program in the United States, with an annual research budget of more than $760 million and major research centers in HIV/AIDS, cardiovascular research, cancer, computational and integrative biology, cutaneous biology, human genetics, medical imaging, neurodegenerative disorders, regenerative medicine, reproductive biology, systems biology, transplantation biology and photomedicine.


Cassandra Aviles
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