We used dry rolling seal spirometers (Model 2130; SensorMedics, Yorba Linda, CA, USA) for pulmonary function test. We accepted the spirometry results, which showed two or more acceptable curves and satisfied reproducibility criteria of American Thoracic Society/European Respiratory Society.1 (link) The spirometry data were recorded on web-hard to be examined for quality control and quality confidence.
After spirometry in KNHANES-VI, eligible subjects with normal spirometry and chest X-ray findings were asked to take part in this study.
Participants who signed the written consent moved to 16 regional university hospitals located within an hour's distance from their households to repeat the spirometry. Spirometry was re-performed by expert technicians who performed the diffusing capacity test ≥ 200 times/year for 5 years or more at the university hospitals.12 (link) All technicians had undergone quality control training.
After spirometry in KNHANES-VI, eligible subjects with normal spirometry and chest X-ray findings were asked to take part in this study.
Participants who signed the written consent moved to 16 regional university hospitals located within an hour's distance from their households to repeat the spirometry. Spirometry was re-performed by expert technicians who performed the diffusing capacity test ≥ 200 times/year for 5 years or more at the university hospitals.12 (link) All technicians had undergone quality control training.
