Efficacy and safety of gefapixant, a P2X3 receptor antagonist, in refractory chronic cough and unexplained chronic cough (COUGH-1 and COUGH-2): Results from two double-blind, randomised, parallel-grou

COUGH-1 (n=730) and COUGH-2 (n=1314) were randomized, double-blind, placebo-controlled Phase 3 trials that evaluated the efficacy and safety of gefapixant in patients with refractory chronic cough and unexplained chronic cough. The primary endpoint was the placebo-adjusted mean change in 24-hour cough frequency (reported as coughs per hour) at 12 weeks (COUGH-1) or 24 weeks (COUGH-2); in both studies, 24-hour cough frequency was measured using the Vitalograph VitaloJAK ambulatory audio recording device. Secondary endpoints included change from baseline in awake cough and the proportion of patients with a ≥30% reduction in 24-hour cough frequency; the proportion of patients with a ≥1.3-point increase in Leicester Cough Questionnaire was an additional secondary outcome in COUGH-2.