Characteristics of asthma resistant to moderate dose inhaled corticosteroid treatment on bronchial...

This study was performed to determine the clinical characteristics of asthmatics with bronchial hyperresponsiveness (BHR) that could not be normalized by 6 months of treatment with a moderate dose of an inhaled corticosteroid (ICS).

Thirty-four symptomatic patients with mild to moderate asthma, who had never received any ICS, were treated with 200 mug of inhaled fluticasone propionate twice a day for 6 months. Spirometry, BHR to methacholine, exhaled nitric oxide (NO) and eosinophils in induced sputum were examined before and 2 and 6 months after beginning treatment.

FEV1 was increased and bronchial responsiveness, exhaled NO and sputum eosinophilia were significantly decreased 2 and 6 months after starting ICS treatment. Bronchial responsiveness was further decreased at 6 months together with a further increase in FEV1. In 13 patients, BHR was not normalized despite the 6 months of treatment. This group showed a higher prevalence of males, those with a smoking history and airflow limitation, a higher eosinophil count in the sputum following 6 months of treatment and a longer history of asthma. Multiple, stepwise, linear regression analysis showed that sputum eosinophilia and lower FEV1/FVC following 6 months of treatment and a longer history of asthma were significant independent determinants for BHR after 6 months of ICS treatment.

These findings suggest that the resistance to a moderate dose of ICS for BHR in asthmatics may be significantly associated with remained airflow limitation, eosinophilic airway inflammation resistive to moderate dose of ICS, and delayed introduction of ICS therapy.