Contributions of 25-hydroxyvitamin D, co-morbidities and bone mass to mortality in Japanese postmenopausal women

It was reported that low bone mineral density (BMD), osteoporotic fractures and low serum 25-hydroxyvitamin D (25-OHVD) levels increase the risk of mortality in elderly Caucasian people. However, there is no data available on the relationship between bone mineral density or 25-OHVD levels and mortality in elderly Asian women. To determine whether or not low bone mineral density (BMD) or low 25-OHVD levels contribute to increased mortality risk, we conducted a prospective observational study in 1232 ambulatory postmenopausal female volunteers. Information was obtained from the subjects on baseline BMD, the serum levels of biochemical indices including 25-OHVD, prevalent fractures, co-morbidities and lifestyle variables. The participants were observed for a total of 6.9 ± 3.6 years (mean ± SD) and a total of 107 participants (8.7%) were dead during the observation. Mortality was assessed and confirmed on the certificates or hospital records or information from their family. In addition to traditional risks for mortality, such as age (Hazard ratio, 1.73, 95% CI, 1.51–1.98, P < 0.01), 25-OHVD level < 50 nmol/l (HR 2.17, 1.27–3.72, P = 0.01), prevalent malignancies (HR 5.60, 3.36–9.31, P < 0.01) and existing osteoporosis (HR 2.14, 1.22–3.75, P = 0.01) were found to be significant independent risk factors for all-cause mortality by using multivariate Cox's regression analysis. It is suggested that prevalent osteoporosis, prevalent malignancy or lower levels of 25-OHVD represent powerful risk factors for mortality.