Low bone mineral density in COPD patients with osteoporosis is related to low daily physical activity and high COPD assessment test scores

Abstract

Wen-Te Liu,1,2,* Han-Pin Kuo,3,* Tien-Hua Liao,4 Ling-Ling Chiang,1 Li-Fei Chen,3 Min-Fang Hsu,5 Hsiao-Chi Chuang,1 Kang-Yun Lee,2,6 Chien-Da Huang,3 Shu-Chuan Ho11School of Respiratory Therapy, College of Medicine, Taipei Medical University, 2Division of Pulmonary Medicine, Department of Internal Medicine, Shuang Ho Hospital, Taipei Medical University, 3Department of Thoracic Medicine, Chang Gung Memorial Hospital, Chang Gung University College of Medicine, 4Department of Respiratory Therapy, Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Taipei, 5Department of Healthcare Administration, Asia University, Wufeng, Taichung, 6Department of Internal Medicine, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan*These authors contributed equally to this workAbstract: COPD patients have an increased prevalence of osteoporosis (OP) compared with healthy people. Physical inactivity in COPD patients is a crucial risk factor for OP; the COPD assessment test (CAT) is the newest assessment tool for the health status and daily activities of COPD patients. This study investigated the relationship among daily physical activity (DPA), CAT scores, and bone mineral density (BMD) in COPD patients with or without OP. This study included 30 participants. Ambulatory DPA was measured using actigraphy and oxygen saturation by using a pulse oximeter. BMD was measured using dual-energy X-ray absorptiometry. OP was defined as a T-score (standard deviations from a young, sex-specific reference mean BMD) less than or equal to -2.5 SD for the lumbar spine, total hip, and femoral neck. We quantified oxygen desaturation during DPA by using a desaturation index and recorded all DPA, except during sleep. COPD patients with OP had lower DPA and higher CAT scores than those of patients without OP. DPA was significantly positively correlated with (lumbar spine, total hip, and femoral neck) BMD (r=0.399, 0.602, 0.438, respectively, all P<0.05) and T-score (r=0.471, 0.531, 0.459, respectively, all P<0.05), whereas CAT scores were significantly negatively correlated with (total hip and femoral neck) BMD (r=-0.412, -0.552, respectively, P<0.05) and (lumbar spine, total hip, and femoral neck) T-score (r=-0.389, -0.429, -0.543, respectively, P<0.05). Low femoral neck BMD in COPD patients was related to high CAT scores. Our results show no significant difference in desaturation index, low SpO2, and inflammatory markers (IL-6, TNF-α, IL-8/CXCL8, CRP, and 8-isoprostane) between the two groups. Chest physicians should be aware that COPD patients with OP have low DPA and high CAT scores.Keywords: chronic obstructive pulmonary disease, osteoporosis, daily physical activity, COPD assessment test, bone mineral density