Risk Factors for Frequent Asthma Exacerbation in Japanese Patients with Refractory Asthma

Abstract

IntroductionThe prevalence of asthma is increasing worldwide. In most patients, asthma can be controlled satisfactorily using a combination of anti-inflammatory drugs, including inhaled corticosteroids and bronchodilators 1 . However, even after treatment with maximum combination therapy, some patients continue to exhibit symptoms despite good compliance with medications and good inhalation technique. Such dif cult-to-control or refractory asthma accounts for approximately 5% of all cases 2 , but the exact prevalence of refractory asthma remains unknown because of the lack of a standardized de nition.Wenzel has proposed several mechanisms that may underlie refractory asthma, such as Abstract : Several endogenous and exogenous aggravating factors have been implicated in patients with refractory asthma. The aim of the present study was to identify which comorbid factors are associated with frequent asthma exacerbation in patients with refractory asthma. Thirteen clinical and environmental factors possibly associated with asthma exacerbation were analyzed using a systematic protocol in 63 patients with refractory asthma, as de ned by American Thoracic Society criteria, as well as in 65 patients with wellcontrolled asthma. Aspirin intolerance, psychological dysfunction, recurrent respiratory infection, and hormonal effects were significantly more prevalent in patients with refractory asthma compared with patients with well-controlled asthma. Factors found to be signi cantly associated with frequent exacerbation during the previous year in Japanese patients with refractory asthma were psychological dysfunction, aspirin intolerance, gastroesophageal re ux, and recurrent respiratory infection. Thus, rigorous treatment of these comorbid factors may result in improvements in refractory asthma.