Upper airway cough syndrome may be the main cause of chronic cough in Japan: a cohort study.

BACKGROUND: Upper airway cough syndrome (UACS) is generally considered a common cause of chronic cough but remains poorly recognised in Japan.

OBJECTIVE: This study aimed to assess whether UACS was a common cause of chronic cough in Japan, as is true in other countries. Interview and examination items were evaluated for their potential use in UACS diagnosis.

METHODS: All patients with chronic cough were preliminarily diagnosed with bronchial asthma, UACS, gastroesophageal reflux disease, or postinfectious prolonged cough, based on interviews and examinations. Treatment centred on nasal steroids was administered to the UACS group and standard treatment to the other groups. The observation period lasted 4 weeks. The subjective cough score at first diagnosis was set at 10, and the final diagnosis was made based on the treatment administered at the time the cough score had decreased to ≤2. The associations between the presence or absence of UACS and interview and examination items were statistically evaluated.

RESULTS: Among 230 patients with chronic cough, 146 were diagnosed with UACS-only. Multivariate logistic regression revealed that the assessment items 'awareness of mucus accumulating in the back of the throat', 'presence of abnormal echography findings', 'absence of associated coughing when exercising' and 'presence of coughing persisting after onset' were significantly correlated with the presence or absence of UACS (p < 0.05).

CONCLUSIONS: UACS may be the most common cause of chronic cough in Japan and may be effectively treated with nasal corticosteroids. Diagnosing UACS might be possible by selecting appropriate interview and examination items.