Chronic obstructive pulmonary disease (COPD) is a chronic inflammatory airway disease associated with various systemic comorbidities including osteoporosis. Osteoporosis and its related fractures are common and have significant impacts on quality of life and even respiratory function in patients with COPD. COPD-associated osteoporosis is however extremely undertreated. Recent studies have suggested that both decreased bone mineral density (BMD) and impaired bone quality contribute to bone fragility, causing fractures in COPD patients. Various clinical risk factors of osteoporosis in COPD patients, including older age, emaciation, physical inactivity, and vitamin D deficiency, have also been described. It is critically important for pulmonologists to be aware of the high prevalence of osteoporosis in COPD patients and evaluate them for such fracture risks. Routine screening for osteoporosis will enable physicians to diagnose COPD patients with comorbid osteoporosis at an early stage and give them appropriate treatment to prevent fracture, which may lead to improved quality of life as well as better long-term prognosis.

Osteoporosis has recently been recognized as a major comorbidity in chronic obstructive pulmonary disease (COPD). We conducted a cross-sectional study in a cohort of 136 Japanese males with COPD to evaluate the prevalence of vertebral fracture (VF) and to explore its relationship with pulmonary function parameters. VFs were present in 108 (79.4%); multiple and severe (SQ grade 2 or 3) VFs were found in 77 (56.6%) and 25 (18.4%), respectively. Multivariate logistic regression analyses revealed that decrease in forced expiratory volume in one second (FEV1.0)/forced vital capacity (FVC) [odds ratio (OR) 0.963, 95% confidence interval (CI) 0.929-998, p = 0.036] was associated with the presence of VF after adjustment for age and that FVC (OR 0.462, 95% CI 0.220-0.968, p = 0.041) and current smoking (OR 2.992, 95% CI 1.128-7.940, p = 0.028) were associated with VF severity (grade 2-3 vs. 1). We also found that FEV1.0 was the sole independent determinant of the number of VFs by stepwise multivariate linear regression (p < 0.001). Bone mineral density (BMD) values were available in 49 subjects. Mean T scores were -2.0 ± 1.2 in femoral neck, -1.4 ± 1.2 in total hip and -1.1 ± 1.4 in lumbar spine. Nineteen patients (38.8%) had a BMD T score less than -2.5. BMD Z scores of all the sites showed a progressive decrease as GOLD stage of COPD advanced (p < 0.05). Our results indicate a high prevalence of osteoporosis in Japanese male COPD patients and a strong inter-relationship between the two diseases, re-emphasizing the urgent need for appropriate intervention to maintain both bone and lung health.

Recent epidemiological studies have revealed that osteoporosis is closely associated with common chronic diseases including diabetes, hypertension, chronic kidney disorders, and chronic obstructive pulmonary disease (COPD). COPD is a chronic inflammatory airway disease but now well known to be associated with various systemic comorbidities including osteoporosis. Osteoporosis and osteoporotic fractures are extremely common in COPD patients, which have significant impacts on their quality of life (QOL), activities of daily life (ADL), respiratory function, and possibly their prognosis. COPD-associated osteoporosis is however extremely under-recognized, hence undertreated. Recent studies have suggested that both decreased bone mineral density (BMD) and impaired bone quality compromise bone strength causing fractures in COPD. In COPD patients, various general clinical risk factors for osteoporosis are present including smoking, older age, low body weight, and physical inactivity. In addition, disease-related risk factors such as decreased pulmonary function, inflammation, glucocorticoid use and vitamin D deficiency/insufficiency have been linked to the development of osteoporosis in COPD. Increased awareness of osteoporosis in COPD, especially that of high prevalence of vertebral fractures is called upon among general physicians as well as pulmonologists. Routine screening for osteoporosis and risk assessment of fractures will enable physicians to diagnose COPD patients with comorbid osteoporosis at an early stage. Timely prevention of developing osteoporosis together with appropriate treatment of established osteoporosis may improve QOL and ADL of the COPD patients, preserve their lung function and eventually result in better prognosis in these patients.

Diminished FVC was associated with prevalent vertebral fractures and decreased BMD in Japanese postmenopausal women without apparent pulmonary diseases. Mechanism of such association between pulmonary function and bone status remains to be determined.

Both BMD and TBS were independently associated with grade 2 or 3 vertebral fracture in COPD male subjects, involving distinct mechanisms. Systemic inflammation, as reflected by increased hsCRP levels, may be involved in deterioration of the trabecular microarchitecture in COPD-associated osteoporosis, whereas BMD decline is most strongly associated with weight loss.