Analysis of One Second Forced Expiratory Volume/Forced Vital Capacity Ratio in Japanese Never-Smokers Undergoing General Health Evaluation

Background Under diagnosis of obstructive lung diseases (OLD) throughout the world suggests the need for wide spread use of spirometry which would also enable early detection of these diseases. As part of Japan's program of general health evaluation spirometry is performed routinely on asymptomatic subjects permitting early detection of airflow limitation before it is clinically apparent. Methods We analyzed the one second forced expiratory volume/forced vital capacity (FEV1/FVC) ratio in 8825 (3887 men and 4938 women) never-smokers undergoing general health evaluation at Tokai University Health Examination and Promotion Center. Results We found that the FEV1/FVC ratio declined with age with a general prevalence of airflow limitation of 5.35% which increased with age in men and women as previously reported. In comparison with the standard values of the Japanese Respiratory Society (JRS), the FEV1/FVC ratio at our center was lower than that of the JRS due possibly to the exclusion of pre-surgical patients with airflow limitation in the JRS population or to the influence of passive smoking and/or environmental pollutants in ours. Conclusion These data encourage us to detect airflow limitation in asymptomatic subjects for early referral to pulmonary physicians before OLD is clinically apparent and moderately advanced.