GPT and chronic obstructive pulmonary disease: COPD, chronic obstructive pulmonary disease; CAD, coronary artery disease; HIWS, healthy individuals with smoking; ALT, alanine transaminase; AS, aspartate transaminase; BMI, body mass index; CRP, C-reactive protein; MLR, monocyte-to-lymphocyte ratio; NLR, neutrophil-to-lymphocyte ratio; PLR, platelet-to-lymphocyte ratio