NEW YORK (Reuters Health) - Computed tomography (CT) of the chest can serve a dual purpose in patients with chronic obstructive pulmonary disease (COPD), measuring both the severity of emphysema and vertebral bone density, physicians in Japan report.
Many features besides the lung are associated with COPD, indicating it is a systemic disease, Dr. Toyohiro Hirai and colleagues at Kyoto University note in the journal Chest; one such feature is osteoporosis. However, the association between the degree of lung involvement and loss of bone density is unclear.
The researchers conducted a survey of 65 clinically stable men with COPD and no history of bone disease or use of corticosteroid drug or other medicines that influence bone metabolism. The average patient age was 68.8 years old.
The average CT scan density of the thoracic vertebrae (T4, T7 and T10), the mid-chest area, was used to determine bone mineral density. The percentage of low-attenuation area in the lungs was used as a quantitative measure of pulmonary emphysema.
“Percentage of low-attenuation area in the lungs correlated with bone density more closely than other risk factors for osteoporosis,” such as age, body mass index, smoking and measures of lung function, Hirai’s group reports.
Moreover, their multiple regression analysis showed that only percentage of low-attenuation area in the lungs and BMI could predict bone density in these patients, indicating that COPD itself is a risk factor for osteoporosis.
CT scanning, they conclude, “is a useful tool for the management of COPD not only as a pulmonary disease, but also as a systemic disease,” with the potential for establishing new strategies to decrease osteoporotic fractures.
SOURCE: Chest, December 2008.