Novel Procedure May Improve Asthma Control

Key Point

An experimental procedure that delivers controlled thermal energy to the airway wall—used in conjunction with medication—may help improve asthma control.

Bronchial thermoplasty, a novel asthma therapy that works by decreasing the smooth muscle mass in the airway, was compared with conventional treatment in a randomized trial conducted at 11 centers in four countries. Evidence of improved asthma control among study participants using this therapy as an adjunct to medication “provide[s] the basis for mounting a placebo-controlled trial involving the use of sham bronchial thermoplasty,” said Gerard Cox, MB, and colleagues reporting in the March 29 New England Journal of Medicine. During bronchial thermoplasty, controlled thermal energy is delivered to the airway wall during a series of bronchoscopies.

In their study, 56 controls were treated with inhaled corticosteroids plus long-acting b2-adrenergic agonists (LABAs), noted the researchers—members of the multinational AIR (Asthma Intervention Research) Trial Group. The 56 subjects in the bronchial thermoplasty group received the novel treatment in addition to inhaled corticosteroids and LABAs. The primary outcome was frequency of mild exacerbations, calculated during three scheduled two-week periods of abstinence from LABAs at three, six, and 12 months. Exacerbations were defined as reduced morning PEF of at least 20% below the average, the need for three or more additional puffs of rescue medication, and/or nocturnal awakening caused by asthma symptoms. Participants ranged in age from 18 to 65 and had moderate or severe persistent asthma that required medication to maintain reasonable asthma control. All subjects kept daily diaries.

From baseline to 12 months, the mean number of mild exacerbations in the bronchial thermoplasty group decreased from 0.35 to 0.18 per subject per week, respectively; in the control group, the respective change in the number of mild exacerbations from baseline to 12 months was nonsignificant (0.28 vs 0.31). “The difference between the two groups in the change from baseline was significant at three months and at 12 months … but not at six months,” the authors noted. The number of severe exacerbations at baseline and 12 months, respectively, was 0.07 and 0.01 in the bronchial thermoplasty group and 0.09 and 0.06 among controls. Among the subgroup of subjects requiring high maintenance doses of inhaled corticosteroids (> 1,000 µg of beclomethasone or the equivalent) showed the greatest difference between the bronchial thermoplasty group and controls.

Patients who received bronchial thermoplasty experienced an increase in adverse respiratory events immediately after the procedure, the authors related. However, the number of adverse events returned to normal during the posttreatment period.

“The interpretation of our results is confounded by the nonblinded study design,” the authors acknowledged. “This limitation is important, given that bronchial thermoplasty is a procedure that may increase the potential for a strong placebo effect”; however, the magnitude and persistence of the beneficial effect seen in their study gives credence to their findings, the researchers added.            

—Adriene Marshall

Reference
Cox G, Thomson NC, Rubin AS, et al. Asthma control during the year after bronchial thermoplasty. N Engl J Med. 2007;356:1327-1337.

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