Prevalence of chronic obstructive pulmonary diseases in general clinics in terms of FEV1/FVC

The prevalence of chronic obstructive pulmonary disease (COPD) continues to increase all over the world. Nonetheless, COPD is often misdiagnosed in general clinics because of insufficient use of spirometry. To estimate the prevalence of COPD in general clinics in Japan, we performed spirometry to screen patients who consulted general clinics. Patients 40 years of age and older who consulted clinics in Nagasaki Prefecture, Japan, for non-respiratory diseases and who met certain inclusion criteria had their airflow limitation measured by spirometry. We defined COPD as forced expiratory volume in the first second (FEV1) over forced vital capacity (FVC) (FEV1/FVC) of < 70% in patients without active pulmonary disease, including physician-diagnosed asthma. Of the 1424 patients included in the study, 193 (13.6%) showed airflow limitation. Airflow limitation was significantly related to older age, male gender and cumulative pack-years. FEV1/FVC in patients with hypertension and chronic hepatitis were significantly lower than in patients without these diseases when adjusted for age, gender and pack-years. We showed that there are potentially a number of cases with COPD that are undiagnosed by general physicians in Japan. Measuring airflow limitation by spirometry in smokers with coexisting diseases, such as hypertension and chronic hepatitis, may be very beneficial because COPD is thought to be a systemic disease. The distribution of spirometers to general clinics is definitely needed to detect undiagnosed COPD.