Body Mass Index Related to Risk of Asthma:
Study Shows Association between Obesity and Asthma

CHICAGO - Increasing levels of body mass index (measure of weight relative to height) are related to the risk of having asthma, according to an article in the July 9 issue of the Archives of Internal Medicine, a member of the JAMA family of journals.

Sylvia Y. N. Young, M.D., M.P.H., of the Department of Epidemiology, Navy Environmental and Preventive Medicine Unit, Sigonella, Italy, and Anne McTiernan, M.D., Ph.D., of the University of Washington School of Public Health and Community Medicine, Seattle, and colleagues conducted a study to examine the association between asthma and obesity.

The researchers selected a random sample of 1,000 asthma cases and 1,000 controls from a military managed health care program encompassing Washington, Oregon, and northern Idaho. The enrollees, aged 17 to 96 years, were linked to a computerized military health record system to verify if medications indicated for asthma therapy were prescribed.

After excluding cases not prescribed bronchodilator medications and excluding controls prescribed bronchodilator medications or steroids, the authors used logistic regression to estimate associations among asthma, body mass index (body weight in kilograms divided by the square of height in meters), and demographic, lifestyle, and comorbid risk factors in 386 verified cases and 744 verified controls.

The researchers found that increasing body mass index, younger age, female sex, non-active duty beneficiary status and arthritis were significant predictors of asthma prevalence in both the larger analysis and the verified substudy. They also determined that stomach ulcer, depression, hypertension, and white race were also predictors of asthma prevalence.

According to background information in the article, patients with asthma commonly have other medical problems such as obesity, but it is unclear if obesity independently relates to asthma occurrence.

In 1990, health care expenditures for illness related to asthma were estimated at $6.2 billion or nearly 1 percent of all U.S. health care costs. Asthma affects approximately 5.6 percent of the general population(10.3 million persons). In the U.S. population, 54.9 percent of adults are overweight (BMI greater than/equal to 25.0) and 22 percent are obese (BMI greater than/equal to 30.0).

"In summary, increasing BMI is a key factor predicting prevalence of asthma and, if determined to be etiologically related to asthma incidence, is a potentially modifiable risk factor for this disease," the authors write. "Prospective cohort data are needed to sort out issues of causality, i.e., does obesity lead to asthma or vice versa. Future studies may include interventional trials to determine if a decrease in weight will cause a decrease in asthma symptoms for overweight asthma patients."

"Instead of parents or clinicians discouraging strenuous exercise in obese children or patients with 'exercise-induced bronchospasm' to manage asthma symptoms, better management may prove to be a program stressing reduced energy intake and increased physical activity aimed at achieving an ideal body weight, thereby reducing asthma symptoms," the authors conclude.

Arch Intern Med. 2001;161:1605-1611; available post-embargo at archinternmed.com) For more information: contact the JAMA/Archives Media Relations Department at 312/464-5374.

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