Bronchial Thermoplasty for Refractory Asthma Update
Even with maximal treatment with medications, some patients with severe asthma remain symptomatic with impaired lung function and quality of life. Bronchial thermoplasty is a new treatment approved by the FDA in 2010 as a therapy for severe asthma not controlled by inhaled corticosteroids and long-acting beta agonists.
Bronchial thermoplasty essentially burns the smooth muscle in the airways by delivering thermal energy through the Alair radiofrequency (RF) catheter during three sequential bronchoscopies. It is theorized that the reduced smooth muscle mass results in reduced asthma symptoms, but the actual mechanism of any benefit of bronchial thermoplasty is unknown.
From randomized trial data, bronchial thermoplasty does not improve lung function (FEV1) or reduce airway hyperresponsiveness. However, patients undergoing bronchial thermoplasty in randomized trials (the largest, AIR-2, published in AJRCCM in 2010) had fewer severe asthma exacerbations, visits to the emergency room, and fewer lost days from work or school.
Bronchial thermoplasty is expensive, and few insurance companies have so far approved payment for the procedure. However, the Centers for Medicare and Medicaid Services agreed in 2012 to pay for the disposable catheters used during bronchial thermoplasty, and other insurers may follow. This could make bronchial thermoplasty a common (and for pulmonologists, probably quite lucrative) outpatient procedure.
Does Bronchial Thermoplasty Work? Evidence from Randomized Trials
Bronchial thermoplasty has been shown in multiple randomized trials to improve asthma symptoms and quality of life, but not FEV1 or airway hyperresponsiveness [1, 2, 3]. The first two of these trials (AIR and RISA) enrolled 244 patients total and did not have sham placebo groups as controls, raising the criticism that the improvement in symptoms among people getting bronchial thermoplasty was purely due to a placebo effect after undergoing an invasive procedure.
The AIR2 trial then randomized 288 people from 30 centers with uncontrolled asthma to undergo either bronchial thermoplasty or a sham bronchoscopic procedure. Patients treated with bronchial thermoplasty had a slight 0.19 point improvement in Asthma Quality of Life Questionnaire (AQLQ) scores (1.35 vs. 1.16 with sham procedure), falling well short of the cutoff of 0.5 points for a “clinically meaningful” improvement in the AQLQ over the sham group. Moreover, both the sham and bronchial thermoplasty groups experienced a clinically meaningful improvement in AQLQ, again raising the question of whether it was the experience of undergoing an invasive procedure that led to the patient-perceived benefits.
No differences were noted between the groups in FEV1, peak flow, or rescue medication use. However, the patients treated with bronchial thermoplasty had significantly fewer emergency room visits, severe exacerbations, and days missed from school or work. These benefits persisted on follow-up studies at 2 years, although the sham group was not followed for comparison.
The AIR2 trial was also criticized because of its approach to patient selection: the average FEV1 was ~78% predicted, although <60% is considered representative of severe asthma by the NAEPP. Patients with more severe asthma (low FEV1, >2 exacerbations or pneumonias in the previous year, or >3 oral steroid bursts in the previous year) were excluded, opening questions about extrapolations of any benefits of bronchial thermoplasty to these patients.
Is Bronchial Thermoplasty Safe? Adverse Events
Bronchial thermoplasty appears generally safe. Temporary increase in airway inflammation after the procedure is common and may require increase in asthma medical treatment. No severe adverse events have been attributed to bronchial thermoplasty.
8% of patients in the AIR2 trial were hospitalized after bronchial thermoplasty, compared to 2% after the sham treatment.
Follow-up studies of the patients in the three clinical trials demonstrate no late-occurring adverse events after up to 5 years of follow up.
Cost of Bronchial Thermoplasty
Like any new product or service in U.S. health care, the precise costs of bronchial thermoplasty are difficult to determine, but probably run into the tens of thousands of dollars per procedure, including three bronchoscopies using three disposable, proprietary catheters that reportedly cost at least $1,500 each.
Only a handful of insurance companies are paying for bronchial thermoplasty, but the Centers for Medicare and Medicaid Services agreed in 2012 to pay for the Alair catheters used during bronchial thermoplasty, which suggests other insurers may follow suit. This could make bronchial thermoplasty a common (and for pulmonologists, probably quite lucrative) outpatient procedure. The Alair RF system reportedly costs $30,000 as a one-time, up-front purchase.
Wahidi MM, Kraft M. Bronchial Thermoplasty for Severe Asthma. Am J Respir Crit Care Med 2012;185:709-714.