What community measurements can be used to predict bone disease in patients with COPD?

Osteoporosis is common in patients with COPD. Previously we have reported that loss of fat-free mass (FFM), measured by dual X-ray absorptiometry (DXA) is associated with loss of bone mineral density (BMD). In addition, in patients with a low body mass index (BMI) and a low FFM, all had evidence of bone thinning, 50% having osteopenia and 50% osteoporosis. We explored the utility of different anthropometric measures in detecting osteoporosis in a community-based COPD population.

Patients with confirmed COPD and not on long-term oral corticosteroids (n=58) performed spirometry. They underwent nutritional assessment by skinfold anthropometry, midarm circumference, calculation of both % ideal body weight (IBW) and BMI. All had DXA assessment of BMD.

A total of 58 COPD patients had anthropometric measurements taken, with a mean age of 66.8 (SD 8.7) years, 31 (58%) were male, with a forced expiratory volume in 1s (FEV(1)) of 54.17 (20.18)% predicted. Osteoporosis was present at either the hip or lumbar region in 14 patients (24%). The useful anthropometric measurements identifying those with osteoporosis were both % IBW and BMI. The adjusted odds ratio for %IBW was 0.93 (95% confidence interval (CI) 0.87, 0.99), p=0.016 and for BMI: 0.79 (0.64-0.98), p=0.03. The receiver operating characteristics (ROC) score for both was 0.88, indicating a good fit.

Osteoporosis is common, even in patients with mild airways obstruction. Nutritional assessment, incorporating a calculation of their BMI or %IBW may confer an additional benefit in detecting those at risk of osteoporosis and guide referral for BMD measurement.