Asthma Branching

Research Indicates Stronger Connection Between Obesity, Incidence of Asthma

A study published in April by the American Thoracic Society showed that the incidence of asthma increases by 50 percent for overweight or obese individuals. Put into context: this means that since 65 percent of U.S. adults are either overweight or obese, the connection could have a tremendous impact on public health.

“Based on what we know about the numbers of new asthma cases that occur in adults and the effect of weight, if you were able to take everybody in this country and make them of normal body mass index, then perhaps you could prevent 500,000 new cases of asthma per year in adults,” says David A. Beuther, M.D., lead author of the study and assistant professor in the Department of Medicine at National Jewish Medical and Research Center, University of Colorado at Denver and Health Sciences Center.

What’s the Connection?
While the connection between obesity and asthma is known, the science behind the correlation is still unclear. Several theories suggest that obesity causes the airway diameter to narrow, which in turn damages the smooth muscles of the airway and mimics asthma.

Others suggest that the connection might be the result of inflammation.

“In other words, obesity is a systemic inflammatory disease,” says Beuther. “That has been well-established and been thought to be the reason why obesity can cause coronary disease, arthritis and other diseases. The fat cells don’t just store fat; they actually make a lot of inflammatory chemicals that presumably could effect the lung as well.”

Bariatric physician Mary Vernon, M.D., FAAFP, CMD, president of the American Society of Bariatric Physicians, Lawrence, Kan., also attributes the prevalence of asthma in obese patients to an increased production of inflammatory chemicals. These chemicals signal the brain to constrict the bronchodilators, which in turn causes the lungs to constrict more, she says.

“Both the metabolism of being obese and the metabolism that helps you get obese generate increased inflammatory chemicals that make any inflammation or irritation worse,” says Vernon.

Perhaps the best evidence of the connection between bariatrics and asthma, Vernon says, is that she has seen marked improvement in asthma, to the point of not requiring medications, after her patients have lost weight.

Several other theories suggest that sleep apnea and gastric esophageal reflux — two conditions prevalent among obese individuals — could be at the root for asthma onset.

“That stomach acid when it gets up into the esophagus can cause problems with asthma,” says Beuther. “It may be that as you aspirate, some of that acid gets into the lung and causes inflammation in the lung (or it) may be a neurological sort of thing that it causes irritation in the esophagus and then nerve pathways cause the airways to constrict. But it’s interesting that asthma tends to worsen at night and reflux tends to worsen at night.”

Market Changes Straight Ahead
While researchers continue to study the mechanisms behind the link between obesity and asthma, the connection could cause a major shift in the respiratory market.

“There are studies out there showing that there is a correlation between obesity and patient asthma and that would then by nature drive up the nebulizers (market),” says Respironics’ Gretchen Jezerc.

ResMed’s Ann Tisthammer also speculates that asthma and obesity will be more closely linked in the future. “Asthma is another market that I forecast will be higher on everyone’s radar in another two to four years. Currently there are physicians and clinicians experimenting with it, probably more so with pediatric patients,” she says.

Certainly, the association with childhood obesity could have the greatest impact on the nebulizer market in the years ahead.

What is known is that childhood obesity is on the rise and the prevalence of asthma among children is already high. The goal for researchers will be to link the increase in asthma rates with the increase in obesity. Beuther says doing so will prove to be difficult because of the hormonal and developmental issues among children.

That being said, a University of Melbourne study released in March looked at childhood obesity and the diagnoses of adult-onset asthma. According to the study, women who were overweight as children more than tripled their risk of developing adult-onset asthma.

“I think the importance of all this is that the direction of this relationship is a two-way street,” says Beuther. “Yes, asthma can cause obesity, but obesity can cause asthma.”

The good news for the bariatric market is that the federal government is taking notice. Already bariatric home medical equipment outside of respiratory has been given unique reimbursement codes in the Medicare system, and the opportunities for bariatric surgery are increasing. Task forces have been formed to address the obesity epidemic, and that will likely fuel research efforts in the future.

“Over the past five to six years, bariatric medical devices have become more requested than ever before,” says Allison Stackpole, director of home care business development, Graham-Field Health Products, Atlanta. “Bariatrics seems to be more popular than it has been, and it’s tied to the fact that we have finally seen the federal government acknowledge that it is an epidemic and there are people who need costly medical devices to be safe and independent in their own home.”

It’s only a matter of time before those efforts trickle down to the respiratory segment.

This article originally appeared in the Respiratory Management May/June 2007 issue of HME Business.

About the Author

Elisha Bury is the editor of Respiratory Management.

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