A new study sheds light on the differences in the way asthma patients respond to inhaled steroid therapy. This study conducted by the National Heart, Lung and Blood Institute’s Asthma Clinical Research Network demonstrated that low to medium doses of inhaled steroids are usually sufficient to improve lung function in patients with persistent asthma.
Increasing to high doses of the inhaled steroids failed to achieve greater improvement in lung function but increased the potential risk for adverse effects. Surprisingly, about a third of the patients (eight of 21 evaluated) in the study showed minimal improvement in lung function at any dose of inhaled steroid. The findings, published in the March issue of the Journal of Allergy and Clinical Immunology, also introduce methods that could be used to identify those who will and will not respond to inhaled steroids.
“Inhaled steroids have greatly improved the overall care and management of asthma during the past 10 years,” said Stanley Szefler, M.D., lead author on the paper and Head of Pediatric Clinical Pharmacology at National Jewish Medical and Research Center. “But we must realize that individual patients respond quite differently to inhaled steroids, and consider other therapies if low to medium doses are not providing a clear benefit.”
Dr. Szefler recommends that doctors whose patients do not respond with low to medium doses of inhaled steroids consider supplementing them with non-steroidal medications, such as long-acting beta agonists and leukotriene modifiers, before prescribing high doses of inhaled steroids. When high doses of steroids are used for several years, they may be associated with an increased risk for adverse effects, such as osteoporosis, cataracts and glaucoma. However, higher doses of inhaled steroids may still be needed to help some patients control their asthma, said Dr. Szefler. He advises doctors to monitor any patients taking high doses to determine whether the benefits outweigh the risk for adverse effects. The new findings indicate that benefits vary widely for individual patients.
The research team studied 30 patients with persistent asthma. The patients received three different doses of an inhaled steroid, each administered for six weeks at a time. The researchers examined two inhaled steroids in this study, fluticasone propionate (FloventTM), and beclomethasone dipropionate (VancerilTM) both in the canister form along with a spacer device. They evaluated benefits primarily by measuring lung function and airway sensitivity. Cortisol levels were measured to gauge the effect of the inhaled steroid on the body’s normal function and the risk for adverse effects.
To the research team’s surprise, eight of the 21 patients (38%) who completed all lung function tests showed less than a 5% increase in lung function at any dose, much less than expected. Five (23%) had a 5% to 15% percent increase in lung function, while eight (38%) had more than 15% improvement in lung function. A similar degree of variability in response was shown for the change in measures of airway sensitivity.
The study team identified certain characteristics, such as exhaled nitric oxide and lung function before treatment, that could be associated with the level of response to the medication. They are conducting further studies in a larger set of patients to test whether these characteristics could be used to predict patient response. This could be a useful clinical tool for selecting treatments for individual patients.
The low to medium doses of each of the two inhaled steroids studied had the greatest effect on lung function with a minimal effect on cortisol levels. The higher doses of both steroids failed to improve lung function or reduce airway sensitivity more than the low to medium doses but they did result in the adverse effect of lower cortisol levels. Dr. Szefler said too few patients were studied to demonstrate differences between the two medications.
“We must test other measures of asthma control, such as the prevention of significant asthma exacerbations, to see if this pattern holds,” said Szefler. “This initial study is important since it highlights the significant variation in response to medications and prompts a whole new area of research that could improve our management of asthma.”
Journal
Journal of Allergy and Clinical Immunology