2.3 Survey development
Each of the patients underwent the following procedures for the investigation of the cause of cough: 1) recording of medical history including symptoms and history of ear, nose, throat, respiratory tract, and digestive tract problems; 2) detailed physical examination with the targeted evaluation of throat congestion, follicular hyperplasia, and retropharyngeal postnasal drip; and 3) chest X-ray examination, bronchodilator test, methacholine-challenge test, CT imaging of the sinuses, or endoscopy in patients with suspicious symptoms or signs.