Design of the Redefining Therapy in Early COPD Study

Redefining Therapy in Early COPD (RETHINC) is a 12-week multicenter, randomized, double-blind, placebo-controlled, parallel-group study to assess the efficacy and safety of indacaterol/glycopyrrolate 27.5/15.6 mcg inhaled twice daily in symptomatic current and former smokers with respiratory symptoms as defined by COPD Assessment Test (CAT) score ≥ 10 despite preserved spirometry defined by post-bronchodilator forced expiratory volume in 1 second (FEV₁) to forced vital capacity (FVC) ratio ≥ 0.70. Recruitment began in July 2017 with the goal of enrolling 580 participants. The baseline examination includes spirometry (with slow and forced maneuvers) and symptom questionnaires. A follow-up phone call at 4 weeks assesses symptoms and safety. The second and final visit at week 12 includes spirometry before and after study drug (hourly over 3 hours) and follow-up symptom questionnaires. The primary endpoint is the proportion of individuals who experience a 4-unit improvement in St George's Respiratory Questionnaire (SGRQ) score at 12 weeks without treatment failure, defined as an increase in lower respiratory symptoms necessitating treatment with active, long-acting inhaled bronchodilators, corticosteroids or antibiotics. Key secondary endpoints include the proportion of individuals with a 2-unit improvement in the CAT score; 1-unit improvement in the Baseline Dyspnea Index (BDI) and Transition Dyspnea Index (TDI), both a 4-unit improvement in SGRQ and a 1-unit improvement in BDI/TDI; and mean change in SGRQ, CAT and BDI/TDI. Other secondary endpoints include area under the curve 0-3 hours for FEV₁ after study drug, change from baseline in trough inspiratory capacity, forced expiratory flow 25%-75% of FVC (FEF_25-75) iso-volume FEF_25-75 and mean change in symptoms and rescue medication use based on daily diary. We anticipate results to be available in 2021. This paper describes the RETHINC study and explains the rationale behind it.