Risk factors of osteoporosis in healthy elderly with unrecognized obstructive sleep apnea: role of physical activity

Abstract

ObjectiveSeveral studies suggest a relationship between bone mineral density (BMD) anthropometric and metabolic variables, and obstructive sleep apnea (OSA); all of these factors have an effect on osteoporosis (OS) risk. This cross-sectional study explores these associations in a large sample of older subjects with and without OSA. MethodsVolunteers were recruited from the PROgnostic indicator OF cardiovascular and cerebrovascular events survey. A total of 461 subjects, aged 68.7 ± 0.8 years, were examined, blood samples were taken, and they were subjected to home polygraphy, assessment of daily energy expenditure (DEE), and dual-energy X-ray absorptiometry. ResultsOsteopenia (OP) was detected in 44% of subjects at the femoral and 39% at the vertebral level, while the prevalence of OS was lower at the femoral (4%) and vertebral (12%) levels. As expected, women had a higher prevalence of OP and OS. Subjects with OP and OS had a tendency to have lower DEE and values of obesity, apnea–hypopnea index (AHI), and indices of hypoxemia (ODI). At the correlation analyses, anthropometric factors and DEE were significantly related to BMD with a slight effect of indices of OSA severity. After adjustment for confounding variables, univariate and multivariate regression analyses showed a strong significant association between femoral and lumbar BMD and T-score and DEE without contribution of metabolic data and with a slight negative effect of respiratory factors. ConclusionsIn this sample of the elderly, physical activity was the best predictor of OS with a slight effect of body mass index. The indices of OSA confirm their protective effect on bone mineral density.