Bone mineral density in patients with chronic obstructive pulmonary disease

Abstract

Osteoporosis is one of extrapulmonary features of COPD. This study was aimed to evaluate bone mineral density (BMD) and its correlation to risk factors in patients with COPD. Forty six patients (28 postmenopausal females, 18 males, the average age, 64.3 ± 7.8 yrs) with different COPD stages participated in the study. Fifteen patients have received inhaled corticosteroids (ICS) 500 to 2000 μg of beclomethasone equivalent daily for 5 to 8 yrs. The controls were 38 non COPD patients (35 postmenopausal females, 3 males) comparable to age, smoking history, and co morbidity. BMD was measured in lumbar vertebrae and proximal parts of right and left hips using X ray dual energy absorptiometry. Osteopenia was found in 20 COPD patients (43.48 %) and osteoporosis was in 11 (23.91 %) ones. The mean T criterion in lumbar vertebrae and both femoral necks of COPD patients was significantly lower compared to controls (р = 0.0010–0.0024). BMD in lumbar vertebrae (р = 0.0005–0.006) and femoral necks (р = 0–0,007) was also lower in COPD patients. Lumbar vertebra height did not differ in COPD patients and the controls. We also analyzed sub-groups of severe (FEV₁ < 50 %_pred.) and mild to moderate COPD patients separately. Those with severe COPD had osteopenia and osteoporosis more often (52.6 % vs 37 % and 36.8 % vs 14.8 %, respectively) and T criterion and BMD in both sites reliably lower. These results suppose a role of hypoxia in development of osteoporosis. Both T criterion and BMD in all sites correlated with body mass index (r = 0,453–0,743, p = 0; and r = 0,425–0,663; р = 0, respectively). There was no correlation between cumulative dose of ICS and BMD. No gender differences of BMD in COPD patients indicated that the loss of BMD in COPD could be relevant to chronic pulmonary disease but not to hormonal disorders. We conclude that loss of BMD is one of the systemic effects of COPD.