Background: Many patients visit primary care clinics or local hospitals with a complaint of prolonged/chronic cough. Among the different types of chronic cough, cough variant asthma (CVA) and postinfectious cough may be the most common types, and their differential diagnosis is difficult. Some physicians tend to prescribe inhaled corticosteroids before establishing a definitive diagnosis.
Methods: We retrospectively investigated useful findings for diagnosis in 77 patients with a complaint of prolonged/ chronic cough to detect meaningful findings for differential diagnosis and to identify problems associated with diagnosis in clinical practice.
Results: CVA was diagnosed in 39 patients, and postinfectious cough was diagnosed in 19. Compared with postinfectious cough, CVA was associated with significant characteristics such as "diurnal variation of symptoms," "response to inhalation of short acting β2 agonist (SABA)," and "recurrent episodes of symptoms." CVA was associated with high FeNO levels as well, and high FeNO levels were specific to CVA. However, these useful characteristics were not significant in the patients who had been prescribed ICS before visiting our hospital.
Conclusions: Medical examination and determination of FeNO levels are useful for the differential diagnosis of prolonged/chronic cough, before treatment with ICS.
Keywords: chronic cough; cough variant asthma; fractional exhaled nitric oxide; inhaled corticosteroid; prolonged cough.