MLR analysis was performed with drug resistance in TB patients as the dependent variable (yes = 1, no = 0) and the following variables as independent variables: smoking status (yes = 1, no = 0), presence of COPD (yes = 1, no = 0), presence of lung cavities (yes = 1, no = 0), history of TB exposure (yes = 1, no = 0), treatment interruption (yes = 1, no = 0), and serum levels of ANKRD22 and SERPING1. Here, SERPING1 is linked to chronic obstructive pulmonary disease.