In the first asthma study that controls for risk factors such as smoking, medication, gastroesophageal reflux, and demographics, researchers from Kaiser Permanente have found that hospitalization for asthma is about five times as likely for obese people than for non-obese people. The findings are published in the September issue of the Journal of Allergy and Clinical Immunology.

Asthma is a condition characterized by airway passage constriction and breathing difficulties that affects over 20 million Americans. Further, about 33% of adults with asthma are also considered obese – defined as having a body mass index (BMI) of 30 or higher. There have been several risk factors that researchers have used to explain the link between obesity and asthma such as smoking, use of oral or inhaled corticosteroid medications, gastroesophageal reflux disorder, and demographics. This new study controls for these factors and builds on the previous research that has found obese people to be more likely to suffer asthma and to have more severe asthma than non-obese people.

Investigators from Kaiser Permanente Center for Health Research in both Portland, OR and Denver, CO surveyed a sample of 1,113 patients in Oregon, Washington, and Colorado who were at least 35 years old and who have persistent asthma. Data were collected about weight, height, smoking habits, other illnesses, treatment and their asthma-specific quality of life, asthma control, and any asthma-related hospitalizations.

Lead author David M. Mosen, Ph.D., MPH (Kaiser Permanente Center for Health Research) notes that, “The big finding here is that even after adjusting for risk factors, obese adults were nearly five times more likely to be hospitalized for their asthma.” Mosen added: “Given that nearly 30 percent of our country is obese, this study is yet another example of the long-term dangers of obesity, along with heart disease, diabetes, stroke and dementia.”

The study also revealed that obese people with asthma used more oral corticosteroids and had a higher incidence of gastroesophageal reflux disorder. In addition, participants who were obese and had asthma were younger and less educated than non-obese people with asthma. This group also had significantly worse asthma control, lower asthma-related quality of life, and a 4.6 times increased risk of asthma-related hospitalizations than non-obese people with asthma.

“The take-home message of this study for clinicians is that obese people with asthma need to be followed more carefully because it’s harder to control their asthma, so they are more likely to end up in the hospital,” said study co-author Dr. Michael Schatz (Chief of Allergy at Kaiser Permanente San Diego Medical Center). “My advice for obese asthmatics is: be vigilant to keep your asthma symptoms in check, make sure you know what to do when your symptoms worsen, and do whatever you can to lose weight.”

Journal of Allergy and Clinical Immunology (2008).
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Written by: Peter M Crosta