Prevalence of airflow limitation in patients diagnosed and treated for symptoms of chronic bronchitis by general practitioners in Tochigi Prefecture, Japan.

Objective: Physicians have provided care to only 0.2 million of the 5.3 million Japanese over the age of 40 years old who have chronic obstructive pulmonary disease (COPD). Among such individuals, many patients with respiratory symptoms diagnosed as chronic bronchitis (CB) are prescribed mainly expectorants. To determine the current status of COPD subjects diagnosed with and treated for CB, we investigated the prevalence of airflow limitation (AFL) in CB patients diagnosed by general practitioners (GPs) and the therapies administered to them.

Methods: Patients receiving treatment by GPs as CB completed a questionnaire and the FEV(1)/FEV(6) ratio was measured by their GPs with a Piko-6. The prevalence of AFL (FEV(1)/FEV(6) <73%) and the correlation between FEV(1)/FEV(6) and FEV(1)/FVC were examined. Prescription behavior and comorbid lifestyle diseases were also examined.

Results: Data from 197 patients with CB were analyzed. Among those who underwent spirometry, the correlation between FEV(1)/FVC and FEV(1)/FEV(6) was r(2)=0.38 (p<0.0001), and the sensitivity and specificity of the Piko-6 were 85.7% and 61.1%, respectively. The prevalence of AFL was 47.2% and increased to 54.1% among patients aged 70-79 years. Expectorants were prescribed for 39.8% of CB patients with AFL, but inhaled bronchodilators were prescribed for only 22.6%. Smoking history and age were significantly higher in the group with AFL than in those without AFL (p<0.05). The prevalence of comorbid lifestyle diseases was 73.1% in patients with AFL.

Conclusion: AFL was prevalent among patients with CB. Therefore, GPs should test pulmonary function in CB patients to ensure that the appropriate therapy is administered.