Characterization of Patients With Refractory or Unexplained Chronic Cough Participating in a Phase 2 Clinical Trial of the P2X3-Receptor Antagonist Gefapixant

Alyn H Morice, Surinder S Birring, Jaclyn A Smith, Lorcan P McGarvey, Jonathan Schelfhout, Allison Martin Nguyen, Zhi Jin Xu, Wen-Chi Wu, David R Muccino, Mandel R Sher

Research output: Contribution to journalArticlepeer-review


PURPOSE: This analysis assesses clinical characteristics of patients with refractory chronic cough (RCC) or unexplained chronic cough (UCC) enrolled in a phase 2 study to better understand this patient population.

METHODS: Patients with RCC/UCC lasting for ≥ 1 year and cough severity visual analog scale (VAS) score of > 40 mm at screening were eligible. Demographics, clinical characteristics, and medical history were collected at baseline. Cough-related measures included cough severity VAS, Cough Severity Diary (CSD), Leicester Cough Questionnaire (LCQ), and a structured cough-trigger questionnaire. Medication history included all medications 30 days before screening and chronic cough treatments within 1 year before screening. Data were summarized using descriptive statistics.

RESULTS: Patients (N = 253; female, 76%; mean age, 60 years) had severe (mean cough severity VAS, 57.5 mm) and long-lasting (median duration, 11 years) cough. The most burdensome self-reported aspects included psychological and social factors (LCQ) and cough frequency and intensity (CSD). Patient-reported triggers were consistent with cough hypersensitivity (e.g., 95% to 96% reported irritation or tickle in throat). Common reported comorbidities included gastroesophageal reflux disease (GERD; 56%), allergic rhinitis (47%), and asthma (30%); 12% of patients had been diagnosed with all 3 conditions. The most common prior medications included inhaled or oral steroids (21%), antihistamines (15%), and antacids (15%).

CONCLUSION: Patients with RCC/UCC had severe, long-lasting, and burdensome cough with clinical features of cough hypersensitivity. Many patients had been diagnosed with GERD, allergic rhinitis, and asthma but had a persistent cough despite treatment of these conditions.

TRIAL REGISTRATION:, NCT02612610; registered November 20, 2015.

Original languageEnglish
Pages (from-to)121-129
Number of pages9
Issue number2
Publication statusPublished - 1 Apr 2021


  • Cough hypersensitivity syndrome
  • Idiopathic chronic cough
  • Persistent cough
  • Refractory cough
  • Troublesome cough


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