Combination inhalers are wildly overprescribed for patients with asthma, and despite best intentions the practice may actually be counterproductive in protecting against exacerbations, respiratory experts say.
Most asthmatic patients in Australia are prescribed a combination long-acting beta agonist and corticosteroid inhaler, despite only a “tiny percentage” needing one, according to respiratory physician Emeritus Professor Craig Mellis.
Writing in Australian Prescriber, respiratory experts Professor Helen Reddel and Professor Nicholas Zwar warned that the higher cost of these combination inhaler therapies could, in part, explain asthma patients’ notoriously poor adherence to their treatment.
While doctors think they are doing the right thing by giving patients all the possible tools they could need, the added financial burden was likely to not only lead to minimal use of the combination inhaler, but also result in patients missing out on their effective preventer medication, they said.
Most patients with asthma could be properly controlled with a very low dose inhaled steroid, Professor Mellis said.
“But it’s become a bit of a reflex for people to assume that asthma equals a combination aerosol,” he said, likening it to prescribing antibiotics for a head cold.
“It’s a mistake, but when you argue with people they take an almost religious stance.”
This well-meaning practice drives up costs for both the patient and the government, with asthma drugs among the highest costs to the PBS.
“Patients may not necessarily be comfortable telling a doctor their concerns about prescription costs, but pharmacists frequently see cost-related decisions being made at the point of purchase,” Professors Reddel and Zwar said.
This was a particular problem when short-acting reliever inhalers were cheaper than inhaled corticosteroids, they said.
“Reliance on reliever inhalers, especially without a preventer, increases the risks of severe asthma exacerbations.”
The authors provided a table outlining the average costs of different drugs, saying many doctors were not aware that most low-dose corticosteroid-only preventers were “substantially” cheaper than combination therapy.
“As clinicians, we need to be aware of the contribution out-of-pocket costs have to patients’ day-to-day adherence, and to know the cost implications of what we prescribe.
“For some patients, offering a more affordable option may make the difference between their choosing to take a regular preventer inhaler, and ‘making do’ with a reliever alone, with the attendant risk of worse outcomes.”
While the combination therapy can reduce exacerbations by 20%, they said that “contrary to expectations, adding a long-acting beta agonist has surprisingly little effect on the use of reliever inhalers”.
The use of combination corticosteroids and long-acting beta agonists had been controversial for decades, Professor Mellis explained.
“If you are on a long-acting beta agonist you are effectively using Ventolin every four hours, 24 hours a day, seven days a week, because that’s exactly how long it sits on the receptor,” he explained.
“Which means that should you have an attack of asthma, you’re not going to respond to Ventolin.”
Because of this tolerance to the beta agonist, more asthmatic patients wound up in the emergency department, he said.
“If you look at the guidelines worldwide they all say the same thing: that this combination should be reserved for patients who are uncontrolled on moderate dose inhaled steroids, where we’re sure they’re taking it, and where we’re sure they’ve got the right inhalation technique and where they’re sure that they have actually got asthma rather than COPD or something else,” Professor Mellis said.
Ensuring patients correctly used their inhaler was another way of saving costs for the patient, as incorrect technique led to wasted medicine and the need to purchase new inhalers more frequently, Professor Reddel said.
“[Incorrect inhaler technique] is the case for such a high proportion of patients (up to 80%) that inhaler technique can be assumed to be incorrect until proven otherwise.”