Ultrasound of the calcaneus and bone mineral density differs in older black and white women but is not impacted by current physical activity

The utility of dual-energy X-ray absorptiometry, calcaneal quantitative ultrasound, and fracture risk indices (FRAX® and Osteoporosis Risk Assessment Instrument) for the identification of women with distal forearm or hip fractures: A pilot study

PURPOSE

Dual-energy X-ray absorptiometry (DXA) is considered the "gold standard" in predicting osteoporotic fractures. Calcaneal quantitative ultrasound (QUS) variables are also known to predict fractures. Fracture risk assessment tools may also guide us for the detection of individuals at high risk for fractures. The aim of this case-control study was to evaluate the utility of DXA bone mineral density (BMD), calcaneal QUS parameters, FRAX® (Fracture Risk Assessment Tool), and Osteoporosis Risk Assessment Instrument (ORAI) for the discrimination of women with distal forearm or hip fractures.

MATERIALS AND METHODS

This case-control study included 20 women with a distal forearm fracture and 18 women with a hip fracture as cases and 76 age-matched women served as controls. BMD at the spine, proximal femur, and radius was measured using DXA and acoustic parameters of bone were obtained using a calcaneal QUS device. FRAX® 10-year probability of fracture and ORAI scores were also calculated in all participants. Receiver operating characteristic (ROC) analysis was used to assess fracture discriminatory power of all the tools.

RESULTS

While all DXA BMD, and QUS variables and FRAX® fracture probabilities demonstrated significant areas under the ROC curves for the discrimination of hip-fractured women and those without, only 33% radius BMD, broadband ultrasound attenuation (BUA), and FRAX® major osteoporotic fracture probability calculated without BMD showed significant discriminatory power for distal forearm fractures.

CONCLUSIONS

It can be concluded that QUS variables, particularly BUA, and FRAX® major osteoporotic fracture probability without BMD are good candidates for the identification of both hip and distal forearm fractures.

A pilot investigation of load-carrying on the head and bone mineral density in premenopausal, black African women

Although the influence of weight-bearing activity on bone mass has been widely investigated in white women, few studies have been conducted in black, African populations. We investigated bone mineral density (BMD) in black South African women, with and without a history of load-carrying on the head. We also investigated whether load carrying may offer protection against low BMD in users of injectable progestin contraception (IPC). Participants were 32 black, South African women (22.4 +/- 3.2 years). Load carrying history was determined by questionnaire and interview; participants were grouped as load carriers (LC; n = 18) or non-load carriers (NLC; n = 14). Ten women were using IPC and 6 were load-carriers. Total body (TB), lumbar spine (LS) and total hip (H) BMD were measured by dual energy X-ray absorptiometry. There were no differences in BMD between LC and NLC, and after controlling for age and BMI using two-tailed partial correlations. IPC users had lower BMD at all sites compared to non-IPC users (p < 0.05) and there were no associations between load carrying and BMD in this group. When IPC users were excluded from analysis, LC had higher LS BMD than NLC (p < 0.005). Correlations were found between the weight of load carried and LS BMD (r = 0.743, p < 0.005), and between years of load carrying and LS and TB BMD (r = 0.563, r = 0.538, respectively; both p < 0.05). Load carrying on the head may offer osteogenic benefits to the spine but these benefits did not appear in women using IPC.

Steps per day: the road to senior health?

In older adults, as in younger individuals, habitual moderate-intensity physical activity is associated with a reduced risk of various chronic health conditions, including certain types of cardiovascular and musculoskeletal disease and certain forms of cancer. However, the pattern of physical activity associated with such benefits remains unclear. One problem is that most investigators have examined patterns of physical activity using either subjective questionnaires or accelerometer or pedometer measurements limited to a single week, despite clear evidence of both the unreliability/invalidity of questionnaires and seasonal changes in activity patterns. Since 2000, we have thus conducted an interdisciplinary study examining the habitual physical activity and health of elderly people living in a medium-sized Japanese town (the Nakanojo Study). In about one-tenth of some 5000 available subjects aged > or =65 years, physical activity has already been assessed continuously for 24 h/day for >8 years using a specially adapted pedometer/accelerometer. This device has a storage capacity of 36 days and can distinguish >10 intensities of physical activity (expressed in metabolic equivalents [METs]). Data have to date been summarized as daily step counts and daily durations of activity of <3 and >3 METs, averaged over a 1-year period. This article provides a detailed overview of both factors influencing habitual physical activity and relationships between such activity and health in an elderly population. To date, analyses have been cross-sectional in type. Substantial associations have been noted between the overall health of participants and both the daily duration of effort undertaken at an intensity of >3 METs and the daily step count. In men, the extent of health is associated more closely with the daily duration of activity of >3 METs than with the daily step count, whereas in women, the association is closer for the step count than for the duration of activity >3 METs. In both sexes, the threshold amount of physical activity associated with better health is greater for physical than for mental benefits: >8000 versus >4000 steps/day and/or >20 versus >5 min/day at an intensity >3 METs, respectively. In other words, better physical health is seen in those spending at least 20 min/day in moderate walking (at a pace of around 1.4 m/s [5 km/h]) and a further >60 min of light activity per day. In contrast, better mental health is associated with much smaller amounts of deliberate physical activity. The daily step count and the daily durations of activity of <3 and >3 METs are all influenced by meteorological factors, particularly precipitation and mean ambient temperature. Activity decreases exponentially to about 4000 steps/day as precipitation increases. Excluding the influence of rainfall, the daily step count peaks at a mean outdoor temperature of around 17 degrees C; above and especially below such readings, physical activity decreases as a quadratic function of temperature. Seasonal changes in microclimate should thus be considered when designing interventions intended to increase the habitual physical activity of elderly people. The observed associations between physical activity and health outcomes point to a need for longitudinal analyses; these should examine potential causal interpretations of the current findings and elucidate possible additional mediating variables.

Impact of overweight and obesity on hospitalization: race and gender differences

OBJECTIVE

To examine associations between weight status and number of all-cause and cause-specific hospitalizations overall, and by race and gender.

DESIGN

Longitudinal cohort study.

SUBJECTS

White and black adults (n=15 355) from the Atherosclerosis Risk in Communities Study who were normal weight (body mass index: >or=18.5 to <25.0 kg m(-2); n=4997), overweight (>or=25.0 to <30.0 kg m(-2); n=6100), or obese (>or=30.0 kg m(-2); n=4258) at baseline.

MEASUREMENTS

Information on hospitalizations was collected using community and cohort surveillance methods. Negative binomial models adjusted for race, gender, field center, age, physical activity, education level, smoking status, alcoholic beverage consumption and health insurance at baseline. Adjusted numbers of hospitalizations were calculated after setting covariates to the mean value (for continuous variables) or to the average distribution (for categorical variables) observed in the entire cohort and are expressed as the number of hospitalizations per 1000 adults followed over a period of 13 years.

RESULTS

The covariate-adjusted average number of all-cause hospitalizations was 1316 per 1000 normal weight, 1543 per 1000 overweight and 2025 per 1000 obese. Normal weight women had significantly fewer hospitalizations than normal weight men (1173 versus 1515 per 1000), but the increase associated with being obese on the number of all-cause hospitalizations was larger in women than men (791 versus 589 per 1000). There was no significant difference detected between the number of hospitalizations in normal weight whites and blacks, and the increase in hospitalizations with overweight or obesity was also not different. Effects of weight status on several primary causes of hospitalization differed by gender and race group.

CONCLUSION

Our work suggests that obesity prevention may reduce hospitalizations, a major component of rising healthcare costs. The impact of successful obesity prevention is likely to be larger in women than in men, and similar in blacks and whites.

Relationship of bone health to yearlong physical activity in older Japanese adults: cross-sectional data from the Nakanojo Study

INTRODUCTION

We determined associations between bone health and the quantity and quality of habitual physical activity in a cohort of 172 free-living Japanese aged 65-83 years (76 men, 96 women).

METHODS

The number of steps taken and the intensity of physical activity were measured every 4 s throughout each 24-h period for 1 year, using a specially adapted accelerometer that distinguished up to 11 levels of physical activity (expressed in metabolic equivalents, METs). At the end of the year, a quantitative ultrasonic technique assessed each participant's osteosonic index (OSI, reflecting bone stiffness in the calcaneus).

RESULTS

The data were significantly described by linear and exponential regression models which showed that in both sexes the OSI score increased with increasing daily physical activity, up to the observed maximum values of approximately 14,000 steps/day and 50 min/day at an intensity >3 METs. However, when data were categorized into quartiles of physical activity, OSI scores were not significantly greater in persons exceeding recommended minimum standards of habitual physical activity (corresponding to counts of around 6,900 and 6,800 steps/day and durations >3 METs of around 18 and 16 min/day in men and women, respectively). All who met such criteria (with the exception of a few women) had OSI scores above the threshold for a clinical diagnosis of osteoporosis. Multivariate-adjusted logistic regression analyses predicted that men and especially women who engaged in <6,800 steps/day and <16 min/day of moderate-intensity physical activity were, respectively, 4.9-8.4 and 2.2-3.5 times more likely to sustain fractures than those participating in >8,200 steps/day and >25 min/day of activity >3 METs.

CONCLUSION

Causation cannot be inferred from a cross-sectional study. Nevertheless, we suggest that from the viewpoint of bone health, elderly people should be encouraged to engage in low- and moderate-intensity habitual physical activity, taking >7,000 steps/day with a duration >15 min/day at >3 METs.