Table 1.

Baseline characteristics of the subjects

Data are presented as mean ± standard deviation. Numbers in parentheses are percentage of subjects. ^*Physician-diagnosed gastroesophageal reflux disease. Modified MRC, Modified Medical Research Council; FEV1, Forced expiratory volume in 1 second; FVC, Forced vital capacity; Emphysema index, the volume fraction of the lung below -950 Hounsfield Units (HU) at full inspiration. Wall area, % = wall area/(wall area + lumen area) × 100. Airtrapping index = ratio of mean lung density on expiration and inspiration × 100.