Dual-energy X-ray absorptiometry in the clinical evaluation of body composition and bone mineral density in patients with chronic obstructive pulmonary disease.

Background: Depletion of fat-free mass (FFM) occurs in a considerable number of patients with chronic obstructive pulmonary disease (COPD).

Objective: The goal of the study was to determine whether dual-energy X-ray absorptiometry (DXA) is an applicable method in the clinical evaluation of body composition in COPD.

Design: In a cross-sectional study in 79 COPD patients participating in a pulmonary inpatient program and in 23 healthy volunteers, DXA was compared with deuterium dilution (Deu) in the estimation of FFM. Bone mineral density (BMD), a DXA measurement, was also compared between the 2 groups.

Results: FFM(DXA) was highly related to FFM(Deu) in men (R2 = 0.93, P < 0.001) and women (R2 = 0.91, P < 0.001). On average, DXA resulted in higher FFM values than did Deu in COPD patients (3.4 kg; P < 0.001) and in healthy volunteers (2.1 kg; P < 0.001). Furthermore, the intramethod difference in FFM was higher in men than in women in the COPD group (P < 0.05) and in healthy volunteers (P < 0.001). BMD was lower in the COPD group than in the healthy, age-matched volunteers (P < 0.001). In 56% of the COPD patients, there were indications of bone mineral loss, defined as a BMD <1 SD of a matched reference population provided by the software. BMD was <2 SDs in 36% of the COPD patients.

Conclusions: DXA appears to be a suitable alternative method to Deu for assessing body composition and is also of value in identifying bone mineral loss in COPD patients, and is therefore applicable in the clinical evaluation of these patients.