Bone Loss at the Lumbar Spine and the Proximal Femur in a Rural Japanese Community, 1990-2000: The Miyama Study

Abstract

Bone mineral density (BMD) was measured over a ten year period in a cohort study in Miyama village, Wakayama Prefecture, Japan, to provide information on rate of bone loss in the mature and elderly population. Four hundred subjects were selected by sex and age decade from the full list of residents born in 1910-1949, and aged 40-79 years at the end of 1989, with 50 men and 50 women in each age decade. Baseline BMD of the lumbar spine and the proximal femur was measured using dual energy X-ray absorptiometry (DXA) in 1990 and again in 1993, 1997 and 2000. Annual rate of change in BMD (% per year) in the lumbar spine in men in their forties, fifties, sixties and seventies was 0.17, 0.55, 0.01 and -0.16, respectively, and in women, -0.87, -0.83, -0.48 and -0.48, respectively. Thus in men, BMD at the lumbar spine increased in all age strata but the oldest, when it decreased, whereas in women, it decreased in all age strata. On the other hand, BMD at the proximal femur decreased in both sexes in all age strata. Our results show that bone loss rates differ depending on the site involved, demonstrating that different strategies are needed for the prevention of bone loss in the spine and hip.Furthermore, we found evidence of differences in BMD for given age strata between birth cohorts. Data in 1990 and in 2000 showed significant improvements for men in their sixties and for women in their fifties, suggesting that future problems of osteoporosis might be less severe than has previously been predicted in Japan.

Risk factors for low BMD in healthy men age 50 years or older: a systematic review

“…At the lumbar spine, on the other hand, several studies reported that BMD increased with age [15,20,22,29]. The overall increase was approximately 1.5-3.5% per decade (unadjusted and adjusted) for men age 60 years and older [20,22].…”

“…Study cohorts were mainly Caucasian participants; however, several studies were Asian cohorts (Japanese and Chinese) [14][15][16][17][18][19], and the Mr. OS study in the United States [20] included some non-Caucasian participants (approximately 11%). There appear to be no major differences in risk factors between these studies; however, it is recognized that not all ethnicities were represented in our review of the literature.…”

“…The overall increase was approximately 1.5-3.5% per decade (unadjusted and adjusted) for men age 60 years and older [20,22]. In a 10-year longitudinal analysis (unadjusted), Yoshimura et al [15] reported that men in their fifties increased by 0.55%/year, no change in the sixties and decreased by 0.16%/year in the seventies. The increases seen at the lumbar spine may be explained by age-related degenerative changes (e.g., osteophytes) that may falsely elevate spine BMD.…”

“…In three studies [15,23,24], the crude rate of loss at the hip was accelerated at later age strata (up to age 80); three other studies [21,22,29] did not find accelerated loss. At the spine, three studies [21,22,29] did not find accelerated rates with age; however, one study found an accelerated gain during the fifties [15].…”

Lactation Among Adolescent Mothers and Subsequent Bone Mineral Density

“…23 Our findings suggest that an adolescent mother who breastfeeds will subsequently have, on average, 7% higher BMD in her femoral neck, thereby protecting against hip fractures for as many postmenopausal years during which women lose approxi- mately 1% of BMD per year. 24,25 Epidemiological evidence to support such protection is noted in a casecontrol study in the United States of 23 cases of postmenopausal women with hip fractures and nearly 500 controls, which reported an adjusted odds ratio of 0.5 (95% CI, 0.2-0.9) per 12-month increase in lifetime breastfeeding. 26 Similarly, the bulk of evidence suggests a positive association between breastfeeding history and BMD in the femoral neck, total hip, and lumbar spine, [27][28][29] although some controlled studies have not demonstrated such an association.…”