By Nina Flanagan
"We found that risk of an emergency department visit or hospitalization for asthma exacerbation decreased by half after bariatric [weight-loss] surgery and remained significantly lower for at least 2 years," the study authors wrote in the report.
The study relied on weight-loss surgery as an "instrument of substantial weight loss," according to the study's lead author Dr. Kohei Hasegawa, an attending physician in the emergency department of Massachusetts General Hospital in Boston. But, the study didn't have any specific information on the patients' weights before and after surgery, according to Hasegawa.
So it's not clear how much weight needs to be lost to make a difference in serious asthma symptoms, or if losing greater amounts of weight was linked to an even greater reduction in asthma flare-ups.
It's also important to note that this study was designed only to find an association between weight-loss surgery and fewer asthma flare-ups; it cannot show that surgery or expected weight loss from the surgery actually caused the reduction in serious asthma symptoms.
Findings from the study were published online recently in the Journal of Allergy and Clinical Immunology.
Asthma is a chronic disease caused by inflamed, narrowed airways. Symptoms of the disease include difficulty breathing, wheezing and coughing. About 25 million people in the United States have asthma, according to the U.S. National Heart, Lung, and Blood Institute.
Weight-loss surgery is generally only recommended for people who are severely obese, according to the U.S. National Institute of Diabetes and Digestive and Kidney Diseases.
There are a variety of weight-loss surgeries available. The three most common are: gastric bypass; gastric sleeve; and the lap band. The first two procedures are the most effective, with 70 to 80 percent of extra weight lost; and the lap band reduces excess weight by about 40 percent, according to Dr. John Morton, chief of bariatric and minimally invasive surgery at Stanford University School of Medicine in California.
The current study analyzed databases from three states: California, Florida and Nebraska. These databases included almost 2,300 obese patients with asthma. They were between the ages of 18 and 54. All had weight-loss surgery between 2007 and 2009.
The researchers found that one to two years before surgery, 22 percent of the group had at least one emergency department visit or hospitalization due to asthma. This was reduced to only 11 percent during the two years following surgery, the study found.
The authors pointed out that they only looked at asthma symptoms severe enough to send someone to the emergency department or hospital. So it's not known what effect weight-loss surgery might have on better-controlled asthma.
Hasegawa, an attending physician in the emergency department of Massachusetts General Hospital in Boston, said his study is important because there has been confusion in the literature looking at the effects of nonsurgical weight loss on asthma.
"Previous studies with modest weight loss show no consistent effectiveness," he explained.
But, combined with the current findings, "these data suggest substantial weight loss is needed to lower the asthma risk," he said.
So, how could weight-loss surgery reduce the number of severe asthma flare-ups?
The study authors noted that previous research has shown that obesity causes inflammation from chemicals called interleukins that are released from excess fat cells. Asthma has also been linked to inflammation.
"Obesity affects so many health variables that can influence asthma: GERD (gastroesophageal reflux disease); activity/exercise; and the need for additional medications for diabetes, pain, etc.," said Dr. Jennifer Appleyard, chief of allergy at St. John Hospital and Medical Center in Detroit.
GERD is a condition where stomach acid backs up into the esophagus, and it's been linked to asthma. "It's important to understand how much these two common and significant diseases are influenced by each other and how important it is to address them both to break that link," Appleyard commented.
This study, she said, "doesn't really address the details of and impact on the 'obesity-asthma link,' which would be something new."
Still, Hasegawa contended that "it's plausible that bariatric surgery-associated weight loss reversed the obesity-asthma link."
However, he cautioned that bariatric surgery isn't a simple fix, and that surgery can be associated with multiple complications. "There is no great nonsurgical weight-loss intervention in this population to date. This should be an important focus for future investigations," Hasegawa pointed out.
But, Morton said, the complication rates for weight-loss surgery aren't much different from other surgeries. "Many people think this is a high-risk surgery, but it has the same low mortality rate [less than one percent] as gallbladder surgery, and advances in laparoscopy have reduced hospitalization to only a two-day stay," explained Morton.
For those considering surgery, he advised people to have bariatric surgery only at an accredited center that provides extensive patient education and pre- and post-surgery support.