Risk factors of osteoporosis in institutionalized older Thai people

There are very few published studies on osteoporosis among the institutionalized elderly in Asian countries, where the incidence of osteoporosis is increasing rapidly. Our objectives were to determine both the prevalence and risk factors of osteoporosis, as assessed by calcaneal bone mineral density (BMD) measurements, in a Thai nursing home.

Activities of daily living, the Mini-Mental State Examination, blood chemistry, body composition analysis, calcaneal quantitative ultrasound (QUS) and serum C-terminal telopeptides of type I collagen (serum beta-CTx) were assessed in 108 older people living in the largest nursing home for the elderly in Bangkok. Calcaneal BMD was measured by dual-energy X-ray absorptiometry (DXA).

The prevalence of osteoporosis, as defined by a calcaneal BMD T-score <1.6, was 79.6%. The prevalence of low bone mass, as defined by a T-score of broadband ultrasound attenuation <1.0, was 80.6%. The prevalence of osteoporosis detected by these two methods was not significantly different (p=1.00). The prevalence of increased bone turnover [with the cutoff point being the mean + 2 standard deviation (SD) of the serum beta-CTx level of a sex- and age-matched control group] was 13.9%. In multiple linear regression analysis, five risk factors -- serum beta-CTx, mental health, mobility index, height and lean body mass -- were able to predict calcaneal BMD at a coefficient of determination R(2)) of 0.54.

These results indicate the importance of mental health and self-care ability as factors associated with osteoporosis. Increased bone turnover was also a significant risk factor of low bone mass. Calcaneal QUS was a useful screening tool for diagnosing osteoporosis in this population and was comparable to calcaneal DXA.