Table 1. Diagnostic criteria of chronic cough.

Causes	Diagnostic criteria
Upper airway cough syndrome	(I) Presence of postnasal discharge, nasal mucosal edema, hyperemia, and faintness; (II) response to an antihistamine, nasal saline, and/or nasal steroid therapy in 2 to 4 weeks
Cough-variant asthma	(I) An isolated chronic, nonproductive cough lasting for more than 4 weeks; (II) airflow limitation demonstrated by bronchodilator responsiveness and/or response to inhaled steroid (budesonide, 400 µg/d) within 4 weeks
Gastroesophageal reflux cough	(I) Esophageal pH monitoring showed that the esophageal pH was <4 for more than 5% of the total monitoring time; (II) response to treatment with a proton pump inhibitor within 2 to 4 weeks
Eosinophilic bronchitis	(I) Normal spirometry with normal airway responsiveness; (II) eosinophil count >3% in non-squamous cell sputum; (III) response to glucocorticosteroids
Protracted bronchitis	(I) A history of chronic moist cough; (II) response to antibiotic therapy (clarithromycin, 15 mg/kg/d for 10 days) with resolution of cough within 2 to 4 weeks
Tic disorders	(I) A neuropsychiatric disorder characterized by a waxing and waning pattern of motor and vocal tics which occur several times a day, nearly every day or intermittently, over the span of more than a year