GRONINGEN, THE NETHERLANDS—Some young adults outgrow asthma, but many others remain asthmatic or develop irreversible airway obstruction (IAO) in later life. A recent Dutch study followed more than 200 asthma patients for 21 to 33 years.[1] The researchers found that a surprisingly high percentage of patients develop irreversible obstruction or reduced carbon monoxide transfer coefficient—but only a few patients acquire both of these characteristics associated with chronic obstructive pulmonary disease (COPD).

“We looked at individuals who had asthma and wanted to know what their prognoses were in the long-term,” said principal author Dirkje S. Postma, MD, PhD. She and her colleagues also sought to determine what factors present in early adulthood might predict the disease’s course later in life.

Surprisingly, IAO and reduced transfer coefficient in later life were each associated with distinct risk factors in young adult asthma patients: Risk for future IAO, which is characteristic of both chronic asthma and COPD, was linked with lower forced expiratory volume in one second (FEV1), less reversibility of airway obstruction, and less severe bronchial hyperresponsiveness during the initial screening. In contrast, the risk for reduced transfer coefficient, suggesting diffusion capacity defects associated with emphysema, was linked with smoking and female sex.

The researchers recruited 228 asthma patients treated at one Dutch clinic between 1962 and 1970. At that time, the patients, whose ages ranged from 13 to 44, had symptoms of asthma, reversible airway obstruction, and a greater than 20% drop in FEV1 following histamine challenge.

Between 1991 and 1998, the patients were reexamined. Lung function and histamine responsiveness were reassessed; additionally, carbon monoxide transfer coefficients were determined for 165 patients. At follow-up, 93 patients (41%) had no evidence of airway obstruction, 97 (43%) had reversible obstruction, and 35 (16%) had IAO. In addition, 38 (23%) of the patients whose transfer coefficients were determined showed reductions suggestive of emphysema. Only nine patients had both IAO and reduced transfer coefficients. Thus, among patients initially diagnosed with asthma, a substantial number later have evidence of COPD, noted Dr. Postma, who is a Professor of Pulmonology at University Hospital in Groningen, the Netherlands.

Patients with reversible airway obstruction reported dyspnea, wheeze, and asthma attacks more frequently than did patients without airway obstruction. In contrast, patients with IAO were more likely to report cough, dyspnea, and phlegm production.

Patients who later developed IAO had lower FEV1 and poorer reversibility of their airway obstruction during their initial examinations. At follow-up, about 50% of patients were not using corticosteroids; these patients were more likely to be diagnosed with IAO than were users. “So, it’s very important [to] treat asthma at an early age,” Dr. Postma said. Unfortunately, inhaled steroids were unavailable when this study started

—Mimi Zucker, PhD