Details regarding the grouping strategy and variables (age, gender, BMI, smoking history, smoking cessation, forced expiratory volume in a second (FEV1)%pred, residual capacity (RV)%pred, ratio of RV to total lung capacity (RV/TLC)%, percentage of emphysema assessed by computed tomography (CT emphysema)%, AE, frequent AE, FETUB, fibrinogen, 78 kDa glucose-regulated protein GRP-78, diabetes mellitus, hyperlipidermia, hepatitis, hypertension, abnormal alanine aminotransferase (ALT) and abnormal aspartate aminotransferase (AST)) are presented in Table 1. Here, GPT is linked to hepatitis A virus infection.