Screening test for airflow limitation.

Forced expiratory time (FET), the time in seconds required to exhale the vital capacity forcefully, was examined as a self-test for airflow limitation. Following only written instructions, 180 subjects measured their own FET. Neither laboratory equipment nor personnel were used. Results were compared with usual spirometric measurements of airflow limitation. Correlation between FET and spirometric measurements was significant. No training effect was evident after a coached spirogram, indicating adequacy of effort and understanding in the performance of the FET test. An FET of greater than five seconds was significantly associate with spirometric abnormality. The FET test missed significant airflow limitation in 9% of subjects, and misclassified 14% of subjects as abnormal. This self-test FET is sensitive enough to warrant field trials.