[Bone mineral density of the lumbar spine and its relation to biological and lifestyle factors in middle-aged and aged Japanese women (Part 1). Relationship of age and menopause to bone mineral density of the lumbar spine measured by dual-energy X-ray absorptiometry]

Use of anthropometric indicators in screening for undiagnosed vertebral fractures: a cross-sectional analysis of the Fukui Osteoporosis Cohort (FOC) study

Background

Vertebral fractures are the most common type of osteoporotic fracture. Although often asymptomatic, each vertebral fracture increases the risk of additional fractures. Development of a safe and simple screening method is necessary to identify individuals with asymptomatic vertebral fractures.

Methods

Lateral imaging of the spine by single energy X-ray absorptiometry and vertebral morphometry were conducted in 116 Japanese women (mean age: 69.9 ± 9.3 yr). Vertebral deformities were diagnosed by the McCloskey-Kanis criteria and were used as a proxy for vertebral fractures. We evaluated whether anthropometric parameters including arm span-height difference (AHD), wall-occiput distance (WOD), and rib-pelvis distance (RPD) were related to vertebral deformities. Positive findings were defined for AHD as ≥ 4.0 cm, for WOD as ≥ 5 mm, and for RPD as ≤ two fingerbreadths. Receiver operating characteristics curves analysis was performed, and cut-off values were determined to give maximum difference between sensitivity and false-positive rate. Expected probabilities for vertebral deformities were calculated using logistic regression analysis.

Results

The mean AHD for those participants with and without vertebral deformities were 7.0 ± 4.1 cm and 4.2 ± 4.2 cm (p < 0.01), respectively. Sensitivity and specificity for use of AHD-positive, WOD-positive and RPD-positive values in predicting vertebral deformities were 0.85 (95% CI: 0.69, 1.01) and 0.52 (95% CI: 0.42, 0.62); 0.70 (95% CI: 0.50, 0.90) and 0.67 (95% CI: 0.57, 0.76); and 0.67 (95% CI: 0.47, 0.87) and 0.59 (95% CI: 0.50, 0.69), respectively. The sensitivity, specificity, and likelihood ratio for a positive result (LR) for use of combined AHD-positive and WOD-positive values were 0.65 (95% CI: 0.44, 0.86), 0.81 (95% CI: 0.73, 0.89), and 3.47 (95% CI: 3.01, 3.99), respectively. The expected probability of vertebral deformities (P) was obtained by the equation; P = 1-(exp [-1.327-0.040 × body weight +1.332 × WOD-positive + 1.623 × AHD-positive])^-1. The sensitivity, specificity and LR for use of a 0.306 cut-off value for probability of vertebral fractures were 0.65 (95% CI: 0.44, 0.86), 0.87 (95% CI: 0.80, 0.93), and 4.82 (95% CI: 4.00, 5.77), respectively.

Conclusion

Both WOD and AHD effectively predicted vertebral deformities. This screening method could be used in a strategy to prevent additional vertebral fractures, even when X-ray technology is not available.

Intake of fermented soybeans, natto, is associated with reduced bone loss in postmenopausal women: Japanese Population-Based Osteoporosis (JPOS) Study

Japanese fermented soybeans (natto in Japanese), which contain a large amount of menaquinone-7, may help prevent the development of osteoporosis. We assessed the possibility of an association between habitual natto intake and bone mineral density (BMD) and BMD change over time in healthy Japanese women who participated in a large representative cohort study (Japanese Population-based Osteoporosis Study: JPOS study). The BMD was measured at the spine, hip, and forearm in 944 women (20-79 y old) at baseline and at a follow-up conducted 3 y later. Dietary natto intake was assessed by a FFQ on both occasions. Additional covariates including age, height, weight, lifestyle factors, dietary calcium intake, and the intake of other soybean products, were also measured. The total hip BMD at baseline increased (P for trend = 0.0034) with increasing habitual natto intake in the postmenopausal women, although this was not the case at other skeletal sites. There were significant positive associations between natto intake and the rates of changes in BMD at the femoral neck (P < 0.0001) and at the distal third of the radius (P = 0.0002) in the postmenopausal women. The association in the femoral neck persisted even after adjusting for covariates. No significant association was observed between the intake of tofu or other soybean products and the rate of BMD change in the postmenopausal women. Natto intake may help prevent postmenopausal bone loss through the effects of menaquinone 7 or bioavailable isoflavones, which are more abundant in natto than in other soybean products.

Trunk muscle strength is a strong predictor of bone loss in postmenopausal women

To clarify whether trunk muscle strength and self-reported exercise habits predict subsequent bone loss in healthy post- menopausal women, we examined 143 community-dwelling ambulatory postmenopausal Japanese women (age: 59.9 +/- 6.5 years) without any diseases affecting bone metabolism at baseline, and followed 109 of the 143 subjects for 4 years. Bone mineral density at baseline and at followup was measured at the spine by DEXA to determine the annual change in bone mineral density during the followup. Subjects who lost bone mineral density at an annual rate exceeding -1.78% (1 standard deviation below the mean rate) were defined as rapid bone losers. The isokinetic concentric and eccentric peak torques of the trunk flexors and extensors were measured at baseline. The exercise habits of the subjects were evaluated through detailed interviews. The eccentric trunk flexor and extensor torques were found to correlate with a positive dose-dependent effect on change in bone mineral density while exercise habits showed no correlation. The lower tertile group for the extensor torque showed a ten-fold greater risk for rapid bone loss compared with the upper tertile group. Postmenopausal women with decreased trunk muscle torque may be at increased risk for osteoporosis and should be a target group for preventive measures.

LEVEL OF EVIDENCE

Prognostic study, level II (prospective study). See the Guidelines for Authors for a complete description of the levels of evidence.

Reference database of biochemical markers of bone turnover for the Japanese female population. Japanese Population-based Osteoporosis (JPOS) Study

The present study was conducted as a part of the Japanese Population-based Osteoporosis (JPOS) Study to establish reference values on the biochemical markers of bone turnover in the general Japanese female population over an applicable age range. The study recruited 3250 women aged 15-79 years, randomly selected from five municipalities throughout Japan, and obtained measurements of serum osteocalcin (OC) and bone-specific alkaline phosphatase (BAP); free and total forms of immunoreactive deoxypyridinoline, free pyridinolines and type I collagen cross-linked C-terminal telopeptide (CTx) in urine; serum intact parathyroid hormone (PTH) and 1,25 dihydroxy vitamin D (1,25 (OH)2D); and bone density at the spine, hip and distal forearm. After excluding subjects with apparent or suggested abnormalities affecting bone mass, 2535 (78%) subjects were further analyzed. The authors presented 5-year age-specific mean values of the markers and mean marker levels derived from women aged 30-44 years with normal bone density as a healthy young adult reference. Values of the markers decreased with increasing age before the age of 40, increased steeply among subjects in their 50s, and remained elevated in the elderly. Serum calcium, phosphorus, PTH and 1,25 (OH)2D levels were higher in postmenopausal women than in premenopausal women. However, 1,25 (OH)2D was lower among early postmenopausal subjects. The levels of OC, BAP, CTx, PTH and 1,25(OH)2D were significantly greater for women with osteoporosis than for those without. The diagnostic value of the markers was limited as the sensitivity and specificity ranged from 55% to 60%. These findings will aid health professionals in the correct assessment of bone turnover status in Japanese women over a wide range of age.

Relationship between total and regional bone mineral density and menopausal state, body composition and life style factors in overweight Japanese women

OBJECTIVE

To investigate whether menopausal state, body composition and lifestyle factors influence total and regional bone mineral density in overweight Japanese women.

DESIGN

Cross-sectional study of women who were recruited to the weight reduction program held at community-based health promotion center in Tokyo area.

SUBJECTS

A total of 178 women with a mean age of 48 y old (20-69 y) with a clear menstrual history and BMI over 24.

MEASUREMENTS

Total, regional and lumbar spine bone mineral density (BMD) and body composition were measured using DXA (Lunar). Menstrual history was taken by a questionnaire and walking steps per day and energy intake were measured. Physical fitness was assessed by cardio-respiratory fitness and leg extension power. Subjects were divided into pre-menopausal and post-menopausal groups.

RESULTS

Pre-menopausal group had significantly higher total body BMD as well as regional BMD than post-menopausal group. However, no differences in BMI, percentage fat and fat mass (FM) were seen between the two groups. The multiple regression analysis stepwise method revealed that total and regional BMD correlated with menopausal state and total FM independently. Total and regional BMD did not correlate with total non-fat soft tissue mass (NFSM), energy intake, walking steps or physical fitness levels. Trunk and lower extremities BMD correlated with corresponding regional FM and NFSM, and upper extremities BMD correlated with only corresponding body part NFSM after adjusting menopausal state.

CONCLUSION

Total and regional BMD had strong negative correlation with menopausal state rather than total FM in overweight Japanese women. Weight-bearing site BMD correlated with corresponding body part FM and NFSM and non-weight bearing site BMD only correlated with corresponding body part NFSM after adjusting for menopausal state.

Osteoporosis and years since menopause

In Fukuoka Prefecture, in south-western Japan, a regional screening program for osteoporosis was conducted from 1994 to 1995. The screening level in the bone mineral density (BMD) at the distal non-dominant radius was equal to or less than two standard deviations below age-specific mean (< or = -2.0 SD). In 1177 examinees with natural menopause (mean age: 61.4, range: 42-88), 56 of those who were screened were subsequently radiologically confirmed by orthopedic specialists to have osteoporosis (case group). They were then compared with 802 normal BMD (> or =-1.0 SD) women (reference group) with their lifestyle and reproductive characteristics. The adjusted odds ratio (OR) and its 95% confidence interval (CI) were calculated using a logistic regression model. A significant increase in the ORs for osteoporosis based on the number of years since menopause was observed for 7-13 years since menopause (OR = 2.3; 95% CI: 1.0-5.4) compared with <7 years, however, no increasing trend in risk was evident in 14+ years since menopause (OR = 1.4; 95% CI: 0.4-5.1). Thus, the elevated risk continued up to around 10 years since menopause. These findings are consistent with previous studies that reported an alternation in the calcium metabolism and bone loss related to the length of time after menopause. Both the childhood and current milk consumption were also associated with a decreased risk: ORs were 0.4 (95% CI: 0.2-0.9) and 0.5 (95% CI: 0.3-1.0), respectively.

Age, menopause, bone turnover markers and lumbar bone loss in healthy Japanese women

The change in lumbar vertebral bone mineral density (BMD) during a 2-year study period was examined in 167 healthy middle-aged and elderly Japanese women with reference to age, menopausal status and bone turnover markers at baseline. The perimenopausal and postmenopausal groups of the subjects showed a significant loss of BMD during the study period but the premenopausal women did not. The annual percent decrease of BMD (delta BMD) in the perimenopausal women (-2.40% in average) was significantly greater than that in either of the premenopausal (-0.01%) or over-all postmenopausal women (-0.85%). The subjects who had been postmenopausal for less than 10 years showed a significant bone loss. delta BMD in the postmenopausal women became less marked as the postmenopausal duration increased. The bone loss was accelerated for about 10 years after menopause. The pattern and magnitude of bone loss of Japanese women seemed to be similar to those of Caucasian women. The regression equation for delta BMD based on the bone turnover markers at baseline was shown to be significant in the postmenopausal women and the serum level of bone-specific alkaline phosphatase isoenzyme had a significant relation to delta BMD. However, this equation accounted for only 17.3% of the total variance of delta BMD and, hence, its validity was not sufficiently high for the prediction of bone loss in clinical settings.

Relative contributions of age and menopause to the vertebral bone density of healthy Japanese women

The relative contributions of age and menopause to vertebral bone mineral density were evaluated based on the estimated weights for age- and menopause-related bone loss components using a mathematical model in 177 healthy female volunteers ages 35-81 years, living in a community in Fukui, Japan. Bone mineral density was determined by dual X-ray absorptiometry. The model used was that which afforded the best fit among the eight possible models to the data observed. Each model was composed of a linear function for the age-related component and a different type of function for the menopausal component, without interaction between them. The weights for these components in each model were estimated by the least-squares method. The coefficient of determination and Akaike information criterion disclosed that among the eight models tested, the model affording the best fit was composed of a logarithmic decrease in bone density with an increase in years since menopause, up to 10 years postmenopausal, with no further decline thereafter. In this model, the weights for both components were statistically significant and the type III sum of squares of the menopausal component was greater than that of the age-related component. We suggest that both age and menopause made significant contributions to the decline in vertebral bone mineral density, with the contribution of menopause being greater than that of age.