Prevalence of sarcopenia in Japanese women with osteopenia and osteoporosis

Sarcopenia and osteoporosis are both significant health burdens among postmenopausal women. This study examined associations between sarcopenia and osteopenia/osteoporosis in Japanese women and evaluated the prevalence of sarcopenia in women with osteopenia and osteoporosis. A total of 2400 Japanese women aged 40–88 years underwent dual-energy x-ray absorptiometry (DXA) scans of the whole body, lumbar spine, and total hip. Osteopenia and osteoporosis were defined according to World Health Organization criteria using bone mineral density (BMD) of the lumbar spine or hip. Sarcopenia was defined as a relative skeletal muscle index (RSMI) more than 2 standard deviations below the mean for a young adult reference population, calculated as the appendicular skeletal muscle mass (ASM) obtained from whole-body DXA divided by height in meters squared (RSMI = ASM/height²). Significant and marginal/moderate positive correlations were observed between RSMI and lumbar spine/total hip BMDs (r = 0.197 and r = 0.274, respectively; p < 0.0001 each). The BMDs of the lumbar spine and total hip showed significant moderate negative correlations with age (r = −0.270 and r = −0.375, respectively; p < 0.0001 each), but RSMI showed no association with age in this population (r = 0.056). When osteopenia/osteoporosis was defined using lumbar spine BMD, prevalences of sarcopenia in subjects with normal BMD, osteopenia and osteoporosis were 10.4, 16.8, and 20.4 %, respectively. When osteopenia/osteoporosis was defined using total hip BMD, the prevalences of sarcopenia in these subjects were 9.0, 17.8, and 29.7 %, respectively. A Chi-square test for independence showed a significant association between sarcopenia and osteopenia/osteoporosis (p < 0.0001). These results indicate that sarcopenia is significantly associated with osteopenia and osteoporosis in Japanese women.