Bronchial thermoplasty improves quality of life and reduces exacerbations in patients with severe asthma — and its effects appear to be long lasting, Martin Phillips from Sir Charles Gairdner Hospital has told TSANZSRS 2015.
Taking delegates through the procedure, Phillips said the idea behind it was that smooth muscle played a role in asthma and by reducing it symptoms should improve.
“One may think that heating up the airways causes a lot of problems but interestingly when you’ve done the procedure it’s actually quite hard to see where you’ve been…when you go back three weeks later you have no idea that you’ve been there,” he said.
Showing the audience a video which illustrated positive outcomes from the procedure Phillips acknowledged that while this was encouraging the proof of the pudding was in the eating.
“The pudding isn’t exactly a sticky date pudding that you’d enjoy with a bit of ice-cream it’s a different type of pudding — it’s probably the entrails of an animal or a pig, stuffed with mincemeat, suet, oatmeal and various other things,” he told the conference.
There were five studies on the effects of the procedure, one of which was the AIR2 study that randomised 297 patients with severe asthma in a 2:1 ratio to treatment or sham procedure.
The study found a significant difference in the primary outcome measure of AQLQ score between the groups, with nearly 80 percent of patients who were treated achieved a clinically significant increase in that score.
There was also a marked improvement in those who received sham therapy, highlighting that treatment and attention can have a profound effect.
Nevertheless, the difference between the sham and treatment group still remained significant, Phillips said.
What was perhaps unexpected, and maybe not predictable from the thesis underlying the role of bronchial thermoplasty, was its effect upon health utilisation, he said.
There was a 66% reduction in severe exacerbations in the treatment group a 23% reduction of unscheduled visits to the physician, a 84% reduction in emergency room attendance and a 73% reduction in hospitalisations.
“That’s quite impressive but the question would be whether that was persistent,” he said.
“And in fact it did persist certainly into year two, and actually more recently up to five years”.
Noting a lack of a sham control (patients in the sham group were offered treatment after a year), Phillips said it was hard to think of a placebo effect that is persistent for so long.
“But clearly, we don’t have a direct comparator,” he said.
The procedure appeared to be safe, and there had been no deaths or significant adverse effects. Patients who required a course of steroids for exacerbations following the procedure tended to do well, he said.
If the procedure were to be accepted as an effective therapy it would not be suitable for every patient with asthma, he said.
“We certainly shouldn’t be offering it to patients who are well controlled.. it might be just some 5-10% of the asthma population” he said.
One of the problems was that it was unclear at this stage who was the right phenotype to receive the treatment.
The mechanism of action was also unclear, he said.
“Early on it appeared to be quite straightforward and had an effect upon smooth muscle but I don’t know, maybe there are other effects..maybe it has an effect on inflammatory response”.
“I think that the pudding is worth eating even if at this stage perhaps we haven’t yet determined the constituents of it,” he concluded.
The bottom line:
- Sham treatment clearly has a significant placebo effect
- Bronchothermoplasty does appear to improve quality of life and reduces exacerbations and health utilisation
- These effects appear to be long lasting
- The ideal phenotype is not clear