Association of Adiponectin with COPD Subtypes Based on Airway Wall Thickening, Emphysema and Thoracic Bone Mineral Density

초록

Adiponectin levels have been separately associated with both osteoporosis and COPD. Osteoporosis is common in COPD subjects particularly with more severe lung disease and emphysema. We hypothesized that adiponectin would show unique associations with bone disease and lung imaging characteristics in COPD subjects and could be used to define subtypes of COPD based on categories of bone disease, airway disease and emphysema. We investigated 425 subjects from the COPDGene study who had quantitative CT measurements of bone density from the thoracic vertebrae and adiponectin levels. Adiponectin levels were measured using a multiplex biomarker assay. Bone disease was categorized as normal, intermediate low bone density and severe low bone density. We identified eight subtypes of combined lung and bone disease based on low/ high values of emphysema, WA% and BMD categories and tested the association of those groups to adiponectin levels with and without adjustment for age, gender, current smoking and BMI using multiple regression analysis. Adiponectin was significantly associated with the subtypes of COPD based on emphysema, WA% and osteoporosis. In particular, adiponectin levels are significantly increased in the group with airway disease and osteoporosis (high WA%, low emphysema and low BMD) ( β = 0.3482, SE = 0.1077, adjusted P-value = 0.0012), in the group with emphysema and osteoporosis (low WA%, high emphysema and low BMD) ( β = 0.4447, SE = 0.1162, adjusted P-value = 0.0001), and in the group with airway disease, emphysema and osteoporosis (high WA%, high emphysema and low BMD) ( β = 0.4135, SE = 0.1044, adjusted P-value < 0.0001). Increased emphysema and osteporosis with or without airway disease in smokers have the highest levels of adiponectin. Our findings suggest that the combination of osteoporosis and lung disease (either emphysema and/or airway disease) associates with higher levels of adiponectin than with bone or lung disease alone in COPD patients.