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Inhaled corticosteroids have been the mainstay of treatment for persistent asthma for decades. A new trial suggests that for the ~50% of asthma patients with low sputum eosinophils, inhaled steroids are no better than placebo, and neither was tiotropium.
Treatment with the inhaled glucocorticoid mometasone or the long-acting muscarinic antagonist tiotropium resulted in similar outcomes among the majority of patients with mild asthma who had low (less than 2%) sputum eosinophil levels. Results from the SIENA trial were published in the New England Journal of Medicine and presented at a society conference.
The study used a randomized, double-blind, placebo controlled crossover design enrolling 295 patients. No significant improvements in asthma outcomes (treatment failure, asthma control days, and the forced expiratory volume in 1 second) were seen with either mometasone or tiotropium relative to placebo, among the patients with low sputum eosinophils.
Those with sputum eosinophilia >2% did respond well to mometasone over placebo, while those receiving tiotropium did not.
Existing asthma treatment guidelines advise inhaled corticosteroids for all patients with persistent asthma. If the SIENA results reflect reality, as many as 50% of such patients will not have sputum eosinophilia and would not benefit from inhaled steroids.
Pediatric pulmonary specialist Andrew Bush, MD, of Imperial College London, who was not involved with the study, told MedPage Today,
The gospel has been that patients with asthma need inhaled steroids -- end of discussion. This study adds to the evidence that this might not be the case, but it is still proof of concept. There is not enough evidence to say you can junk inhaled steroids in this group, but there is enough to warrant a definitive trial to determine if we can do that."
Routine testing for sputum eosinophilia is not feasible on a large scale in the U.S. today, where 26 million people are believed to have asthma. Inhaled nitric oxide testing has been proposed as a surrogate for detection of airway inflammation, but has not entered widespread use.
The trial was small and inconclusive, and its immediate effect will be to open the door to the design of larger trials randomizing patients with mild persistent asthma and absence of sputum eosinophilia to long-acting muscarinic antagonists or inhaled steroids vs. placebo.
The SIENA trial was funded by the National Heart, Lung, and Blood Institute.