Study Raises Doubts About 'Outgrowing' Asthma

Peggy Peck

May 22, 2003

May 21, 2003 (Seattle) — As many as one in three people who had childhood asthma who were asymptomatic at age 18 years are likely to have recurrent, symptomatic disease by age 26 years, according to findings reported here in a poster session at the American Thoracic Society (ATS) 99th International Conference.

Robin R. Taylor, MD, of the University of Otago School of Medicine in Dunedin, New Zealand, told Medscape that "the results suggest that once one has asthma there is no guarantee that the person can be rid of it." Dr. Taylor said his study contradicts the notion that "one can simply outgrow asthma."

Dr. Taylor and colleagues have followed a birth cohort of 1,037 New Zealanders for more than 26 years. Detailed respiratory histories were obtained every two years until age 15 years and then again at ages 18, 21, and 26 years. Of the 1,037 study participants, 176 reported physician-diagnosed asthma when interviewed at age 9, 11, 13, or 15 years, he said.

Sixty-eight of the 176 study enrollees with an asthma history were asymptomatic at age 18 years.

"But by age 21, 16 of these asymptomatic young adults had relapsed to current symptomatic asthma and by age 26, eight more developed symptoms. So we had a recurrence rate of 35%," Dr. Taylor said.

Homer A. Boushey, Jr., MD, professor of medicine and chief of the division of allergy/immunology and director of the Asthma Clinical Research Center at the University of California, San Francisco, told Medscape that the study suggests "that people really don't grow out of asthma." Many clinicians thought that "simple geometry could diminish asthma: as the body grows, the airway grows and a bigger airway is less likely to be prone to obstruction." But he said that theory has diminished in recent years.

"In this study, they are reporting an incidence of about 16%, that is actually much higher than in the United States where we estimate asthma at about 5.5%, so that is a significant difference that might reflect some environmental factors," said Dr. Boushey, who is president-elect of ATS.

Some researchers have found that a biopsy of persons who have been asymptomatic for a year or more "find the same number of inflammatory cells as are found in persons with symptomatic asthma," Dr. Boushey said. Those findings suggest that asthma can persist as a low-grade, subclinical condition, which may explain the high "recurrence" rate reported by Dr. Taylor, he said.

Dr. Taylor said that in New Zealand, police, fire departments, and the military "want to know if someone who has a past history of asthma in remission is at risk for recurrence." Dr. Boushey said he was puzzled by this concern. "Asthma is a very treatable condition. I think we need to be very careful to avoid stigmatizing people with asthma."

While Dr. Boushey said risk of asthma recurrence should not be considered as a barrier to any career, he did agree with Dr. Taylor that asymptomatic adults with a history of childhood asthma should be cautioned about smoking. "No one should smoke, but these are patients who need to have that message really driven home," said Dr. Boushey. Dr. Taylor said it is possible that smoking might increase the risk for recurrence of asthma or "it is possible that these people are at risk for [chronic obstructive pulmonary disease] and smoking will increase that risk."

The study was funded by the Health Research Council of New Zealand.

ATS 99th International Conference: Abstract 304. Presented May 21, 2003.

Reviewed by Gary D. Vogin, MD

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