Nearly half of patients with mild-to-moderate asthma have non-eosinophilic phenotype
MONDAY, Jan. 23 (HealthDay News) -- Approximately half of all patients with mild-to-moderate asthma are persistently non-eosinophilic, according to a study published online Jan. 20 in the American Journal of Respiratory and Critical Care Medicine.
Kelly Wong McGrath, of the University of California in San Francisco, and colleagues analyzed data from clinical trials for 995 patients with mild-to-moderate asthma, to determine the prevalence and clinical characteristics of the non-eosinophilic phenotype. Participants underwent sputum induction and measures of sputum cytology as well as an evaluation of response to standardized treatments. Sputum eosinophilia was defined as having ≥2 percent eosinophils, and was classified as persistent, intermittent (at least one occasion), and persistently non-eosinophilic.
The researchers found that, in cross-sectional analyses, sputum eosinophilia was seen in 36 percent of those not taking an inhaled corticosteroid (ICS) versus 17 percent treated with an ICS. Eosinophilia absence was also seen in patients whose disease was suboptimally controlled. In repeated measures analyses of patients not taking an ICS, persistent eosinophilia, intermittent eosinophilia, and persistent non-eosinophilia were seen in 22, 31, and 47 percent of patients. Two weeks of treatment with the bronchodilator albuterol yielded similar results for eosinophilic and non-eosinophilic asthma; however, combined anti-inflammatory therapy resulted in significantly improved airway obstruction for those with eosinophilic asthma but not for non-eosinophilic patients.
"Approximately half of patients with mild-to-moderate asthma have persistently non-eosinophilic disease, a disease phenotype that responds poorly to currently available anti-inflammatory therapy," the authors write.