Factors Associated with Indacaterol Response in Tuberculosis-Destroyed Lung with Airflow Limitation

BACKGROUND: Pulmonary tuberculosis can result in anatomical sequelae, and cause airflow limitation. However, there are no treatment guidelines for patients with a tuberculosis-destroyed lung. Recently, indacaterol effectiveness in chronic obstructive pulmonary disease (COPD) patients with Tuberculosis history (INFINITY) study revealed indacaterol provided bronchodilation and symptom improvement in COPD patients with a tuberculosis-destroyed lung. METHODS: We conducted a post-hoc subgroup analysis of the randomized controlled trial, the INFINITY study, to determine factors associated with indacaterol response in a tuberculosis-destroyed lung with airflow limitation. Data from 68 patients treated with inhaled indacaterol, were extracted and analyzed. Factors associated with the response of forced expiratory volume in one second (FEV(1)) to indacaterol treatment, were determined using linear regression analysis. RESULTS: Of 62 patients included, 68% were male, and 52% had history of cigarette smoking. Patients revealed mean FEV(1) of 50.5% of predicted value with mean improvement of 81.3 mL in FEV(1) after indacaterol treatment for 8 weeks. Linear regression analysis revealed factors associated with response of FEV(1) to indacaterol included a short duration of smoking history, and high short-acting bronchodilator response. When patients with history of smoking were excluded, factors associated with response of FEV(1) to indacaterol included high short-acting bronchodilator response, and poor healthrelated quality of life score as measured by St. George's Respiratory Questionnaire for COPD. CONCLUSION: In a tuberculosis-destroyed lung with airflow limitation, short-acting bronchodilator response and smoking history can play a critical role in predicting outcomes of indacaterol treatment.