Leicester Cough Questionnaire validation and clinically important thresholds for change in refractory or unexplained chronic cough.

"Conflict of interest statement: The authors declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: AMN, JS, DM, and CLR are employees of Merck Sharp & Dohme LLC, a subsidiary of Merck & Co., Inc., Rahway, NJ USA, who may own stock and/or hold stock options in Merck & Co., Inc., Rahway, NJ, USA EDB is an employee of Evidera, which provides consulting and other research services to pharmaceutical, medical device, and related organizations. In her salaried position, she works with a variety of companies and organizations and is precluded from receiving payment or honoraria directly from these organizations for services rendered. Evidera received funding from Merck & Co., Inc., Rahway, NJ USA, to participate in the study and the development of this manuscript. MV reports nonfinancial support from Merck & Co., Inc., Rahway, NJ USA, and personal fees from Evidera during the conduct of the study. SSB reports grants from Merck & Co., Inc., Rahway, NJ USA; being a developer of the LCQ; personal fees for advisory board work from Bayer, Bellus, GSK, Menlo, Merck & Co., Inc., Rahway, NJ USA, Nocion, Sanofi, and Shionogi; and reimbursement for travel expenses from Boehringer Ingelheim."

"Funding: The authors disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: Funding for this research was provided by Merck Sharp & Dohme LLC, a subsidiary of Merck & Co., Inc., Rahway, NJ, USA."