Predictors of low bone mineral density in elderly males with chronic obstructive pulmonary disease: the role of body mass index

OBJECTIVE: The aim of this study was to investigate the relationships between nutritional indices (Body mass index (BMI), serum albumin), sarcopenia, bone mineral density (BMD) and the severity of their pulmonary obstruction in elderly patients with chronic obstructive pulmonary disease (COPD). METHODS: The method involved was a prospective transversal study; 82 males >65 years old, 41 stable patients with COPD and 41 healthy elderly individuals (controls). All subjects underwent spirometry, biochemical analyses and dual energy X-ray absorptiometry. The significance of the differences between mean values and prevalence rates was tested. The relationships between BMD and independent predictors were analysed by multiple linear regressions. Logistic regression models were applied on dichotomised variables. RESULTS: In patients with COPD, the prevalence of osteoporosis was higher in subjects with sarcopenia (46% vs. 0%; p < 0.05) and with BMI < 25.1 kg/m(2) (58% vs. 15%; p < 0.02). Multiple regression analysis indicated that BMI, appendicular skeletal muscle mass (ASMM), albumin, and forced expiration volume after 1 s (FEV1) explained the 70% of BMD variability at the hip and 56% at the spine. Logistic regression showed that a BMI < 25.1 kg/m(2) was independently associated with osteoporosis risk (OR = 10.0; 95%CI 1.3-76); no independent effect emerged for FEV1% (<and 50%). CONCLUSION: In elderly males with COPD, the BMI values < or =25 kg/m(2) are more strongly related to low BMD levels than albumin values. Among those patients, BMI values within the normal range for younger adults might point out a higher risk of osteoporosis.