Factors Associated with Dysfunctional Breathing in Patients with Difficult to Treat Asthma

Background: Understanding of dysfunctional breathing in patients with difficult asthma who remain symptomatic despite maximal inhaler therapy is limited. Objective: We characterized the pattern of dysfunctional breathing in patients with difficult asthma and identified possible contributory factors. Methods: Dysfunctional breathing was identified in patients with difficult asthma using the Nijmegen Questionnaire (score >23). Demographic characteristics, asthma variables, and comorbidities were assessed. Multivariate logistic regression was performed for dysfunctional breathing, adjusted for age, sex, body mass index, and airflow obstruction. Results: Of 157 patients with difficult asthma, 73 (47%) had dysfunctional breathing. Compared with patients without dysfunctional breathing, those with dysfunctional breathing experienced poorer asthma status (symptom control, quality of life, and exacerbation rates) and greater unemployment. In addition, more frequently they had elevated sino-nasal outcome test scores, anxiety, depression, sleep apnea, and gastroesophageal reflux. On multivariate analysis, anxiety (odds ratio [OR], 3.26; 95% CI, 1.18-9.01; P =.02), depression (OR, 2.8; 95% CI, 1.14-6.9; P =.03), and 22-item sino-nasal outcome test score (OR, 1.03; 95% CI, 1.003-1.05; P =.03) were independent risk factors for dysfunctional breathing. Conclusions: Dysfunctional breathing is common in difficult asthma and associated with worse asthma status and unemployment. The independent association with psychological disorders and nasal obstruction highlight an important interaction between comorbid treatable traits in difficult asthma.