Risk Factors Associated With Persistent Airflow Limitation in Severe or Difficult- to-Treat Asthma* Insights From the TENOR Study

Regimens study is among the largest to assess persistent airflow limitation and the first to evaluate a wide range of potential risk factors in high-risk patients with severe or difficult-to-treat asthma. A better understanding is needed regarding factors associated with persistent airway obstruction; this study was performed to determine demographic and clinical characteristics associated with persistent airflow limitation. Methods: Data from adult patients (> 18 years old) with severe or difficult-to-treat asthma were evaluated. Patients with COPD, obesity with a restrictive respiratory pattern, or a> 30 pack-year history of smoking were excluded. Patients with persistent airflow limitation (postbronchodilator FEV1/FVC ratio < 70 % at two annual consecutive visits) and normal postbronchodilator FEV1/ FVC ratio (75 to 85%) were compared. Multivariate analysis identified factors independently associated with persistent airflow limitation. Results: Of 1,017 patients, 612 patients (60%) showed evidence of persistent airflow limitation. Risk factors were as follows: older age (odds ratio [OR] per 10 years, 1.4; 95 % confidence interva