A new study by researchers in Northern Ireland has revealed that difficult-to-treat asthma often may have more to do with patients who do not take their medication as prescribed than ineffective medication.
"[A] significant proportion of patients with difficult asthma are poorly adherent to inhaled and oral corticosteroid therapy," said principal investigator, Dr. Liam Heaney, of Belfast City Hospital.
"Defining the scale and identifying non-adherence in this population is important given currently available and other imminent expensive biological therapies," Dr. Heaney added.
For the study, Dr. Heaney and colleagues obtained data from almost 200 patients who were referred to a tertiary referral clinic that specializes in treating difficult asthma.
To assess compliance with inhaled corticosteroid therapy (ICT), they compared patient prescription to the patient's actual refill usage. They used blood plasma prednisolone and cortisol levels to evaluate oral medication adherence.
Of the 182 consecutive patients, 35 percent filled fewer than half of their prescribed inhaled combination therapy (ICT), 21 percent filled more than they were prescribed and 45 percent filled between half and all of the medication they were prescribed.
Furthermore, in patients who were on a maintenance course of oral prednisolone, blood levels of cortisol and prednisolone showed that nearly half (45 percent) were not taking the medication as prescribed.
In follow-up conversations with the researchers, most admitted that they were inconsistent in the use of their medications. Of the 23 patients who were non-adherent to their oral prednisolone, 15-or 65 percent-were also non-adherent to their ICT.
"All subjects had initially denied poor medication adherence, and poor adherence only became apparent using a combination of surrogate and objective measures," said Dr. Heaney.
"Of these patients who were referred for assessment and treatment of difficult asthma, many are actually not taking their treatment as prescribed, which would suggest an important first course of action in assessing difficult asthma may actually be verifying the patient's adherence to his or her treatment protocol.
"Determining whether the patient is taking medications as prescribed is of utmost importance before moving to more aggressive and expensive treatments. It is also crucially important in understanding true refractory disease and assessing responses to novel therapies, either in clinical trials or clinical practice," Dr. Heaney added.
The results of the study were published in the November 1 issue of the American Journal of Respiratory and Critical Care Medicine, an official publication of the American Thoracic Society.