Association between airflow limitation severity and reduced bone density in Japanese males

Background: To date, limited data exist on airflow limitation (COPD) and bone mineral density in Japan. Aims and Objectives: To assess the association between airflow limitation (AL) severity and reduced bone density in Japanese males. Methods: This cross-sectional study included 296 subjects (mean age 71.2, SD 12.7), who underwent a comprehensive health examination that included spirometry and measurement of bone mineral density (BMD) at the left femoral neck on DXA in 2016-2017 at Japanese Red Cross Kumamoto Health Care Center. AL was defined as FEV1 / FVC of < 0.7. Reversibility tests were not performed for this study. AL severity was defined in accordance with the Global Initiative for COPD criteria. BMD was classified as normal: 88.6% ≦ YAM (-1 SD ≦), osteopenia: 70% -2.5 SD), and osteoporosis: YAM ≦ 70% (≦ -2.5 SD) based on the young adult mean (YAM). Reduced bone density was defined as osteopenia, osteoporosis, or medication use for osteoporosis. Logistic regression analysis was used to assess the association between AL severity and reduced bone density. Results: The prevalence of reduced bone density in subjects with moderate-to-severe AL (76.2%) was significantly higher than those with normal lung function (44.6%) (p=0.019). In logistic regression models adjusted for age, BMI, Pack-year, physical activity, and alcohol drinking, the risk of reduced bone density (odds ratio 3.92; 95% confidence intervals 1.22-12.65; p=0.022) was significantly higher in subjects with moderate-to-severe AL compared to those with normal lung function. Conclusions: Present results suggest that reduced bone density is associated with AL severity in Japanese males.