Low-Dose Aspirin Lowers Risk Of Asthma Diagnosis

In a large, randomized, placebo-controlled study of 22,071 healthy male physicians, taking a low-dose of aspirin every other day lowered the risk of receiving an initial asthma diagnosis by 22 percent.

These findings, based on data from the double-blind Physicians' Health Study, appear in the second issue for January 2007 of the American Journal of Respiratory and Critical Care Medicine, published by the American Thoracic Society.

Tobias Kurth, M.D., Sc.D., of the Division of Aging at Brigham and Women's Hospital in Massachusetts, and five associates studied physicians, ages 40 to 84, over a period of 4.9 years. Among the 11,037 individuals who took aspirin, 113 new cases of asthma were diagnosed, as contrasted to 145 in the placebo group.

Asthma is a chronic inflammatory disease that causes potentially reversible obstructive lung problems. Breathing difficulties from asthma usually occur during "attacks," which involve narrowing of the airways, swelling of the lining, tightening of respiratory muscles and an increased secretion of mucus. In 2004, more than 20 million Americans were estimated to have asthma.

"Aspirin reduced the risk by 22 percent of newly-diagnosed adult-onset asthma," said Dr. Kurth. "These results suggest that aspirin may reduce the development of asthma in adults. They do not imply that aspirin improves symptoms in patients with asthma."

"Indeed, asthma can cause severe bronchospasm in some patients who have asthma," he continued. "Because asthma was not the primary endpoint of the U. S. Public Health Service study, additional randomized trials would be helpful to confirm the apparent reduction in asthma incidence caused by aspirin."

The Physicians Health Study, which began in 1982, was terminated after 4.9 years when results showed a 44-percent reduction in the risk of a first heart attack among those randomly assigned to aspirin.

"Physicians could self-report an asthma diagnosis on questionnaires at baseline, at six months and annually thereafter," said Dr. Kurth. "Asthma was not the original deductive endpoint of the trial."

According to the authors, the 22-percent lower risk of newly-diagnosed asthma among those assigned to the low-dose aspirin group was not affected by participant characteristics like smoking, body mass index or age.

They noted that aspirin-intolerant asthma, a problem in which aspirin exacerbates the disease, affects only a small minority of asthma patients. In three large population-based studies, that difficulty affected only four to 11 percent of the groups. In children, however, the proportion affected by aspirin intolerant asthma was significantly smaller.

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Contact: Suzy Martin
American Thoracic Society