Bone Mineral Density as a Predictor of Subsequent Wrist Fractures: Findings From the Women's Health Initiative Study

CONTEXT

Wrist fractures are common among postmenopausal women. Associations of bone mineral density (BMD) and 10-year predicted risk of major osteoporotic fracture (MOF) with wrist fractures are poorly characterized.

OBJECTIVE

The objective was to examine associations between the Fracture Risk Assessment Tool (FRAX)-predicted risk of MOF, BMD, BMD change, and wrist fracture.

DESIGN

This was a prospective observational study with a mean follow-up of 8.5 years.

SETTING

This study included 40 US centers.

PARTICIPANTS

A total of 11 392 participants from the Women's Health Initiative BMD Cohort aged 50-79 years at baseline were included in this study.

INTERVENTIONS

None.

MAIN OUTCOME

The goal was to measure incident wrist fracture.

RESULTS

A FRAX-predicted MOF risk ≥9.3% identified 17% of the women aged <65 years who subsequently experienced wrist fracture. Each one standard deviation lower BMD was associated with higher wrist fracture risk, with adjusted hazard ratio (95% confidence interval) of 1.66 (1.42-1.93) for femoral neck (FN) BMD and 1.45 (1.28-1.64) for lumbar spine BMD. Compared with FN BMD T score ≥ -1.0, wrist fracture adjusted hazard ratios (95% confidence interval) were: 1.51 (1.06-2.16) for a T score between -1.01 and -1.49; 1.93 (1.36-2.72) for T score between -1.50 and -1.99; 2.52 (1.77-3.60) for a T score between -2.00 and -2.49; and 2.65 (1.78-3.95) for a T score ≤ -2.5. Decrease in FN BMD between baseline and year 3 was associated with increased risk of subsequent wrist fracture; however, change in lumbar spine BMD was not.

CONCLUSIONS

Lumbar spine and femoral neck BMDs were associated with incident wrist fracture, but the FRAX threshold recommended to identify screening candidates did not identify the majority of women who subsequently experienced wrist fracture. Improved understanding of determinants of wrist fractures is warranted.

Wrist Fracture and Risk of Subsequent Fracture: Findings from the Women's Health Initiative Study

Wrist fractures are common in postmenopausal women and are associated with functional decline. Fracture patterns after wrist fracture are unclear. The goal of this study was to determine the frequency and types of fractures that occur after a wrist fracture among postmenopausal women. We carried out a post hoc analysis of data from the Women's Health Initiative Observational Study and Clinical Trials (1993-2010) carried out at 40 US clinical centers. Participants were postmenopausal women aged 50 to 79 years at baseline. Mean follow-up duration was 11.8 years. Main measures included incident wrist, clinical spine, humerus, upper extremity, lower extremity, hip, and total non-wrist fractures and bone mineral density (BMD) in a subset. Among women who experienced wrist fracture, 15.5% subsequently experienced non-wrist fracture. The hazard for non-wrist fractures was higher among women who had experienced previous wrist fracture than among women who had not experienced wrist fracture: non-wrist fracture overall (hazard ratio [HR] = 1.40, 95% confidence interval [CI] 1.33-1.48), spine (HR = 1.48, 95% CI 1.32-1.66), humerus (HR = 1.78, 95% CI 1.57-2.02), upper extremity (non-wrist) (HR = 1.88, 95% CI 1.70-2.07), lower extremity (non-hip) (HR = 1.36, 95% CI 1.26-1.48), and hip (HR = 1.50, 95% CI 1.32-1.71) fracture. Associations persisted after adjustment for BMD, physical activity, and other risk factors. Risk of non-wrist fracture was higher in women who were younger when they experienced wrist fracture (interaction p value 0.02). Associations between incident wrist fracture and subsequent non-wrist fracture did not vary by baseline BMD category (normal, low bone density, osteoporosis). A wrist fracture is associated with increased risk of subsequent hip, vertebral, upper extremity, and lower extremity fractures. There may be substantial missed opportunity for intervention in the large number of women who present with wrist fractures.

Effect of vitamin D supplementation alone or with calcium on adiposity measures: a systematic review and meta-analysis of randomized controlled trials

CONTEXT

The independent or interactive effects of vitamin D and calcium on adiposity remain inconclusive.

OBJECTIVE

The objective of this systematic review and meta-analysis was to assess whether vitamin D and calcium supplements cause changes in adiposity.

DATA SOURCES

MEDLINE, Embase, and the Cochrane Central Register of Controlled Trials databases were searched for literature published from 1966 to March 2014.

STUDY SELECTION

A systematic search was conducted for randomized clinical trials with ≥ 50 participants aged ≥ 18 years at baseline who had received at least 12 weeks of treatment. Among the inclusion criteria were supplementation with vitamin D with or without calcium and measurement of adiposity (weight, body mass index [BMI], and/or fat mass).

DATA EXTRACTION

The primary endpoints assessed were changes in weight, BMI, or fat mass.

DATA SYNTHESIS

Of 953 trials identified, 26 randomized clinical trials (n = 12, vitamin D alone; n = 10, vitamin D plus calcium versus calcium control; n = 4, vitamin D plus calcium versus placebo) with a total of 42,430 participants (median duration, 12 months) met the inclusion criteria. When compared with placebo, vitamin D supplementation had no significant effect on BMI (weighted mean difference [WMD], -0.06 kg/m(2); 95% confidence interval [95%CI], -0.14 to 0.03), weight (WMD, -0.05 kg; 95%CI, -0.32 to 0.23), or fat mass (WMD, -0.43 kg; 95%CI, -1.69 to 0.84). Likewise, no significant reduction in BMI (WMD, 0.02 kg/m(2); 95%CI, -0.11 to 0.14), weight (WMD, 0.12 kg; 95%CI, -0.24 to 0.49), or fat mass (WMD, 0.12 kg; 95%CI, -0.22 to 0.45) was observed in participants who received vitamin D plus calcium compared with those who received calcium control.

CONCLUSIONS

Supplementation with vitamin D showed no effect on adiposity measures in adults.

Sex Differences in the Effects of Weight Loss Diets on Bone Mineral Density and Body Composition: POUNDS LOST Trial

CONTEXT

Weight loss is associated with reduction in bone mineral density (BMD).

OBJECTIVE

The objective was to address the role of changes in fat mass (FM) and lean mass (LM) in BMD decline in both sexes.

DESIGN

A 2-year randomized controlled trial, the Preventing Overweight Using Novel Dietary Strategies (POUNDS-LOST).

SETTING

The setting was the general community.

PATIENTS OR OTHER PARTICIPANTS

Enrolled were 424 overweight and obese participants (mean age, 52 ± 9 y; 57% females).

INTERVENTION

Intervention included weight loss diets differing in fat, protein, and carbohydrates.

MAIN OUTCOME MEASURES

Main outcome measures were change in spine, total hip (TH), and femoral neck (FN) BMD and sex differences after dietary intervention.

RESULTS

At baseline, a stronger correlation between BMD and body composition measurements was observed in women, primarily with LM (r = 0.419, 0.507, and 0.523 for spine, FN, and TH, respectively; all P < .001). In men, only LM correlated with hip BMD (r = 0.298; P < .001). Mean weight loss at 2 years was -6.9%, without differences among diets. Two-year changes in BMD were 0.005 (P = .04), -0.014 (P < .001), and -0.014 g/cm(2) (P < .001), at the spine, TH, and FN, respectively. These changes directly correlated with changes in LM in women (r = 0.200, 0.324, and 0.260 for spine, FN, and TH, respectively), whereas FM loss correlated only with changes in TH BMD (0.274; P < .001). In men, changes in LM (-0.323; P < .001) and FM (-0.213; P = .027) negatively correlated with changes in spine BMD.

CONCLUSIONS

Weight loss diets result in sex-specific effects on BMD. Although men exhibited a paradoxical increase in spine BMD, women tended to decrease in BMD at all sites.

Longitudinal association of measures of adiposity with serum antioxidant concentrations in postmenopausal women

BACKGROUND/OBJECTIVES

The relationship between obesity and circulating levels of antioxidants is poorly understood. Most studies that have examined the association of adiposity with blood or tissue concentrations of antioxidant micronutrients have been cross-sectional, and few have compared the associations for indices of overall obesity and central obesity. Our aim was to prospectively examine the longitudinal association of body mass index (BMI), waist circumference (WC), waist circumference-height ratio (WCHtR) and waist-hip ratio (WHR) with major serum antioxidants in a population of postmenopausal women.

SUBJECTS/METHODS

We used a subsample of participants in the Women's Health Initiative aged 50-79 years at entry with available fasting blood samples and anthropometric measurements obtained at multiple time points over 12.8 years of follow-up (N=2672). Blood samples were used to measure α-carotene, β-carotene, β-cryptoxanthin, lutein+zeaxanthin, α-tocopherol, γ-tocopherol and retinol at baseline, and at years 1, 3 and 6. We used mixed-effects linear regression analyses to examine associations between anthropometric measures and serum antioxidants at baseline and over time, controlling for covariates.

RESULTS

In longitudinal analyses, carotenoids, and particularly β-carotene, were strongly and inversely associated with BMI, WC and WCHtR and less so with WHR. α-Tocopherol showed a strong positive association with WHR but not with other anthropometric measures, whereas γ-tocopherol was positively and strongly associated with BMI, WC, WCHtR and less so with WHR. Retinol was positively associated with WHR. The inverse association of several carotenoids with anthropometric measures was stronger in never and former smokers compared with current smokers and in women without the metabolic syndrome. The inverse association of carotenoids with obesity measures may reflect reduced micronutrient concentrations owing to inflammation associated with obesity.

CONCLUSIONS

In the present study, the strongest observed associations between anthropometric variables and micronutrients were an inverse association of WC with serum β-carotene and a positive association of WC with γ-tocopherol.

Abstract P6-10-04: Statins and breast cancer stage and mortality in the Women's Health Initiative cohort

Background: Statins are the most widely prescribed cholesterol-lowering drugs in the United States, with approximately 25% of US adults using statins by 2008. The anti-carcinogenic effect of statins may reduce the metastatic potential of cancer cells leading to ‘stage migration’ with statin users more likely diagnosed with early rather than late stage cancer. We evaluated the effects of statins on breast cancer stage migration and breast cancer-specific mortality in the Women’s Health Initiative (WHI) Clinical Trial and Observational Study. Methods: The study population included 128,675 postmenopausal women aged 50 to 79 years, with 7,883 newly-diagnosed pathologically-confirmed cases of in situ (19%), local stage (61%), regional stage (19%) and distant stage (1%) breast cancer and 401 deaths due to breast cancer after an average of 11.5 (SD=3.7) years of follow-up. To reduce the possibility of detection bias, we excluded women who did not report a mammogram within 5 years of study entry, and who had no health insurance or medical care provider (n=28,237). Stage was coded using criteria implemented in the Surveillance, Epidemiology and End Results Program and stratified into early stage (in situ and local) vs. late stage (regional and distant). Information on statin use prior to breast cancer diagnosis was collected at baseline and years one, three, six, and nine years post-baseline. Self- and interviewer-administered questionnaires were used to collect risk factor information. Cause of death was based on medical record review by physician adjudicators. Cox proportional hazards regression models were used to calculate hazard ratios (HR) with 95% confidence intervals (CI) to evaluate the relationship between statin use as a time-dependent exposure and diagnosis of late stage breast cancer and breast cancer-specific mortality adjusting for important confounders. For these models, participants who had early stage breast cancer or who died during follow-up were censored at time of diagnosis or death, respectively. We also evaluated the effect of statins stratified by estrogen receptor (ER) status. Statistical tests were two-sided. Results: Statins were used by 10,474 women (8%) at baseline. In the multivariable-adjusted time-dependent model, statin use was associated with a marginal reduction in risk of late stage breast cancer (HR 0.84, 95% CI: 0.70-1.02, p=0.082) and a reduction in risk of late stage estrogen receptor positive breast cancer (HR 0.79, 95% CI: 0.63-0.99, p=0.044). Statin use was also associated with a marginal reduction in breast cancer-specific mortality although it did not reach statistical significance (HR 0.59, 95% CI: 0.32-1.06, p=0.075). Conclusions: In the WHI, statin use was associated with a modest reduction in risk of late stage estrogen positive breast cancer and a non-significant decrease in breast cancer mortality. We are currently performing sensitivity analyses on these models. Studies using other large data sets with longer follow-up and information on cancer-directed therapy are needed to further evaluate this possible association.

Citation Format: Monica P Arun, Pinkal Desai, Amy Lehman, Marilyn L Kwan, JoAnn E Manson, Sayeh Lavasani, Sylvia Wasswertheil-Smoller, Gloria E Sarto, Meryl S LeBoff, Jane Cauley, Michele L Cote, Jennifer Beebe-Dimmer, Allison Jay, Rowan T Chlebowski, Michael S Simon. Statins and breast cancer stage and mortality in the Women's Health Initiative cohort [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P6-10-04.

VITAL-Bone Health: rationale and design of two ancillary studies evaluating the effects of vitamin D and/or omega-3 fatty acid supplements on incident fractures and bone health outcomes in the VITamin D and OmegA-3 TriaL (VITAL)

RATIONALE

Although vitamin D is widely used to promote skeletal health, definitive data on benefits and risks of supplemental vitamin D alone on bone are lacking. Results from large, randomized controlled trials in the general population are sparse. Data on the effects of supplemental omega-3 fatty acids (FAs) on bone are also limited.

DESIGN

The VITamin D and OmegA-3 TriaL (VITAL) is a double-blind, placebo-controlled trial assessing the role of vitamin D3 (2000 IU/d) and omega-3 FA (1g/d) supplements in reducing risks of cancer and cardiovascular disease among U.S. men aged ≥50 and women aged ≥55. To comprehensively test effects of supplemental vitamin D and/or omega-3 FAs on skeletal health, the VITAL: Effects on Fractures ancillary study is determining the effects of these supplements on incident fractures among 25,875 participants enrolled in the parent trial. Study investigators adjudicate fractures through a detailed review of medical records and radiological images (hip and femur). In a complementary ancillary, VITAL: Effects on Structure and Architecture is determining the effects of supplemental vitamin D and/or omega-3 FAs on bone with detailed phenotyping during in-person visits. Comprehensive assessments of bone density, turnover, structure/architecture, body composition, and physical performance are being performed at baseline and 2 years post-randomization.

CONCLUSION

Results from these studies will clarify the relationship between supplemental vitamin D and/or omega-3 FAs on bone health outcomes, and inform clinical care and public health guidelines on the use of supplemental vitamin D for the primary prevention of fractures in women and men.

Effect of age on regulation of human osteoclast differentiation

Human skeletal aging is characterized as a gradual loss of bone mass due to an excess of bone resorption not balanced by new bone formation. Using human marrow cells, we tested the hypothesis that there is an age-dependent increase in osteoclastogenesis due to intrinsic changes in regulatory factors [macrophage-colony stimulating factor (M-CSF), receptor activator of NF-κB ligand (RANKL), and osteoprotegerin (OPG)] and their receptors [c-fms and RANK]. In bone marrow cells (BMCs), c-fms (r = 0.61, P = 0.006) and RANK expression (r = 0.59, P = 0.008) were increased with age (27-82 years, n = 19). In vitro generation of osteoclasts was increased with age (r = 0.89, P = 0.007). In enriched marrow stromal cells (MSCs), constitutive expression of RANKL was increased with age (r = 0.41, P = 0.049) and expression of OPG was inversely correlated with age (r = -0.43, P = 0.039). Accordingly, there was an age-related increase in RANKL/OPG (r = 0.56, P = 0.005). These data indicate an age-related increase in human osteoclastogenesis that is associated with an intrinsic increase in expression of c-fms and RANK in osteoclast progenitors, and, in the supporting MSCs, an increase in pro-osteoclastogenic RANKL expression and a decrease in anti-osteoclastogenic OPG. These findings support the hypothesis that human marrow cells and their products can contribute to skeletal aging by increasing the generation of bone-resorbing osteoclasts. These findings help to explain underlying molecular mechanisms of progressive bone loss with advancing age in humans.

Clinician's Guide to Prevention and Treatment of Osteoporosis

The Clinician's Guide to Prevention and Treatment of Osteoporosis was developed by an expert committee of the National Osteoporosis Foundation (NOF) in collaboration with a multispecialty council of medical experts in the field of bone health convened by NOF. Readers are urged to consult current prescribing information on any drug, device, or procedure discussed in this publication.

Does hormone replacement normalize bone geometry in adolescents with anorexia nervosa?

Young women with anorexia nervosa (AN) have reduced secretion of dehydroepiandrosterone (DHEA) and estrogen contributing to skeletal deficits. In this randomized, placebo-controlled trial, we investigated the effects of oral DHEA + combined oral contraceptive (COC) versus placebo on changes in bone geometry in young women with AN. Eighty women with AN, aged 13 to 27 years, received a random, double-blinded assignment to micronized DHEA (50 mg/day) + COC (20 µg ethinyl estradiol/0.1 mg levonorgestrel) or placebo for 18 months. Measurements of areal bone mineral density (aBMD) at the total hip were obtained by dual-energy X-ray absorptiometry at 0, 6, 12, and 18 months. We used the Hip Structural Analysis (HSA) program to determine BMD, cross-sectional area (CSA), and section modulus at the femoral neck and shaft. Each measurement was expressed as a percentage of the age-, height-, and lean mass-specific mean from an independent sample of healthy adolescent females. Over the 18 months, DHEA + COC led to stabilization in femoral shaft BMD (0.0 ± 0.5% of normal mean for age, height, and lean mass/year) compared with decreases in the placebo group (-1.1 ± 0.5% per year, p = 0.03). Similarly, CSA, section modulus, and cortical thickness improved with treatment. In young women with AN, adrenal and gonadal hormone replacement improved bone health and increased cross-sectional geometry. Our results indicate that this combination treatment has a beneficial impact on surrogate measures of bone strength, and not only bone density, in young women with AN.

Vitamin D Deficiency Treatment Patterns in Academic Urban Medical Center

OBJECTIVE

Assess racial/ethnic and sex differences in treatment of vitamin D deficiency with high dose ergocalciferol ('vitamin D2') or other forms of vitamin D in a northeastern U.S. ambulatory clinic of an academic urban medical center.

STUDY DESIGN

Cross-sectional observational review of electronic medication prescribing records of patients with 25-hydroxyvitamin D (25OHD) deficiency (25OHD < 20 ng/ml) from 2004-2008.

METHODS

Using multivariable logistic regression adjusting for patients' demographics, and Elixhauser comorbidity score, we examined the association of sex and race/ethnicity with prescription for at least one dose of vitamin D.

RESULTS

Among 2,140 patients without renal disease and tested for 25OHD deficiency (25OHD < 20 ng/ml), 66.2% received no vitamin D prescription for vitamin D deficiency. Blacks and Hispanics received vitamin D prescriptions at a higher frequency than whites, 37.8% 38.4% and 30.9%, respectively, p=0.003. The vitamin D prescription rate for women versus men was 26.3% and 7.5%, respectively, p=0.04. In a fully adjusted model, no difference in prescription likelihood for blacks and whites [OR=1.18 95% CI, 0.88-1.58; p=0.29] or Hispanics and whites was noted [OR=1.01 95% CI, 0.70-1.45;p=0.73]. Similarly, fully adjusted model showed no difference in prescription likelihood for females and males [OR=1.23 95% CI, 0.93-1.63; p=0.12].

CONCLUSIONS

Among primary care patients with vitamin D deficiency, vitamin D supplementation was low and white patients were less likely to receive vitamin D treatment than blacks or Hispanics. Interventions to correct the high prevalence of vitamin D deficiency should address the markedly low rate of vitamin D prescribing when 25OHD levels are measured.

OPG and sRANKL serum levels and incident hip fracture in postmenopausal Caucasian women in the Women's Health Initiative Observational Study

PURPOSE

The osteoprotogerin/receptor activator of NF-kappa β/receptor activator of NF-kappa β ligand (OPG/RANK/RANKL) pathway plays a critical role in bone remodeling. This study investigated associations between serum levels of OPG, soluble RANKL (sRANKL), and the ratio of OPG/sRANKL to risk of incident hip fracture.

METHODS

A nested case-control study was conducted among postmenopausal, Caucasian women aged 50-79 at baseline (1993-1998), followed for hip fracture through March 2005 in the Women's Health Initiative Observational Study. 400 incident hip fracture cases were selected and individually matched to 400 controls with no prior fracture or incident hip fracture. Matching factors were baseline age, enrollment date and hormone therapy (HT) exposure. Baseline serum OPG and sRANKL levels were measured using high sensitivity ELISA. Odds ratios were computed for quartiles of each biomarker adjusting for matching factors and hip fracture risk factors.

RESULTS

Serum OPG was significantly associated with older age, low physical activity and poorer physical function in control women. sRANKL was inversely associated with total calcium intake in control women, but not associated with age or other fracture risk factors. The odds ratio for hip fracture comparing the highest to lowest quartiles of OPG was 2.28 (95% confidence interval (CI), 1.45-3.61) after adjusting for the matching variables (p-value for linear trend <0.001), and 1.87 (95% CI, 1.15-3.04; p for linear trend=0.02) after adjusting for self-rated health status, physical activity and physical functioning. No significant associations between sRANKL or the ratio of OPG/sRANKL and hip fracture risk were observed.

CONCLUSION

Serum OPG levels were independently associated with a nearly twofold increased risk of hip fracture in postmenopausal women.

Vitamin D metabolism and action in human marrow stromal cells: effects of chronic kidney disease

Human marrow stromal cells (hMSCs) are targets of 1α,25-dihydroxyvitamin D [1α,25(OH)2D3] action to promote their differentiation to osteoblasts, but they also participate in vitamin D metabolism by converting 25-dihydroxyvitamin D3 [25(OH)D3] to 1α,25(OH)2D3 by 1α-hydroxylase (CYP27B1). Chronic kidney disease (CKD) is associated with impaired renal biosynthesis of 1α,25(OH)2D, low bone mass, and increased fracture risk. We tested whether CKD influences hMSCs' responses to vitamin D3 metabolites. The hMSCs were obtained from tissues discarded during arthroplasty for hip osteoarthrosis, including a subject who had been undergoing hemodialysis for 2+ years. There was a significant positive correlation between in vitro stimulation of osteoblastogenesis (alkaline phosphatase activity) by 1α,25(OH)2D3 and subjects' estimated glomerular filtration rate (eGFR, r=0.47, p=0.015, n=26, 56-83 years of age). Osteoblastogenesis was stimulated in hMSCs from both the hemodialysis and control subjects by 1α,25(OH)2D3 (10μM), 25(OH)D3 (100μM), or D3 (1000μM). Thus, vitamin D metabolism may play an autocrine/paracrine role in osteoblast differentiation of hMSCs. These findings suggest that in CKD patients 25(OH)D-sufficiency may play an important role in skeletal health; osteoblastic bone formation in CKD patients may not be optimal unless there is sufficient serum 25(OH)D substrate for the MSCs to synthesize and respond to local 1α,25(OH)2D. This article is part of a Special Issue entitled 'Vitamin D Workshop'.

Effect of dietary composition of weight loss diets on high-sensitivity c-reactive protein: the Randomized POUNDS LOST trial

OBJECTIVE

Overweight and obesity are associated with increased high-sensitivity C-reactive protein (hsCRP) levels. The purpose of this study was to determine if weight loss diets differing in fat, protein, or carbohydrate composition differentially reduce hsCRP.

DESIGN AND METHODS

POUNDS (preventing overweight using novel dietary strategies) LOST was a 2-year trial of overweight and obese adults randomly allocated to one of four weight loss diets with targeted percentages of energy derived from fat, protein, and carbohydrates (20, 15, 65%; 20, 25, 55%; 40, 15, 45%; 40, 25, 35%, respectively). hsCRP was measured at baseline, 6, and 24 months among 710 participants, and adiposity as measured by dual X-ray absorptiometry (N = 340) or abdominal computed tomography (N = 126) was correlated with hsCRP change.

RESULTS

At 6 months, hsCRP was reduced in all trial participants by -24.7% (Interquartile range (IQR) +7%, -50%), weight by -6.7% (IQR -3%, -11%), and waist circumference by -6.0% (IQR -3%, -10%) (all P < 0.002), with no significant differences according to dietary composition. The percent change in hsCRP at 6 and 24 months correlated modestly with change in weight, waist circumference, fasting insulin, fasting glucose, HOMA, and most lipid levels. Reductions in hsCRP persisted despite ∼ 50% regain of weight by 24 months. The percent change in hsCRP at 24 months significantly correlated with changes in total body fat (r = 0.42), total abdominal adiposity (r = 0.52), subcutaneous abdominal adiposity (r = 0.52), visceral adiposity (r = 0.47), and hepatic tissue density (r = -0.34) (all P < 0.0006).

CONCLUSION

Weight loss decreased hsCRP by similar magnitude, irrespective of dietary composition. Clinicians concerned about inflammation and cardiovascular risk should recommend weight loss diets most likely to succeed for their patients.

Hip geometry in diabetic women: implications for fracture risk

OBJECTIVE

Women with type 2 diabetes mellitus (T2DM) have a higher risk of fractures despite increased bone mineral density (BMD) as compared to women without diabetes. We hypothesized that bone strength is diminished in women with T2DM after accounting for lean body mass, which may contribute to their increased fracture risk.

METHODS

Participants from Women's Health Initiative Observational Study were included in this cross-sectional study. These analyses include 3 groups of women: 1) T2DM women on diet or oral hypoglycemic agents (n=299); 2) T2DM women on insulin therapy (with or without oral agents) (n=128); and 3) Non-diabetic control women (n=5497). Hip structural analyses were done using the validated Beck's method on hip scans from dual energy x-ray absorptiometry (DXA). We compared BMD and section modulus (bending strength) at the narrow neck with and without correcting for total body DXA lean body mass.

RESULTS

Women in all three groups were of similar ages (63.7, 64.6 and 64.2 years, respectively) and heights, but those with T2DM were heavier, with greater lean body weight vs controls (P<.001). In both diabetic groups, absolute BMD and section modulus were higher compared with controls. However, after adjusting for total lean body weight, diabetic women on insulin had significantly lower BMD and section modulus.

CONCLUSION

Adjusted for lean body weight, the BMD and bending strength in the femoral neck are significantly lower in insulin-treated diabetic women vs controls. This may represent altered adaptation of bone modeling and explain the higher fracture risk in patients with T2DM.

Clinical characteristics influence in vitro action of 1,25-dihydroxyvitamin D(3) in human marrow stromal cells

Vitamin D is important for bone health, with low vitamin D levels being associated with skeletal fragility and fractures. Among its other biological activities, 1,25-dihydroxyvitamin D (1,25(OH)(2) D), stimulates the in vitro differentiation of human marrow stromal cells (hMSCs) to osteoblasts, which can be monitored by increases in alkaline phosphatase enzyme activity or osteocalcin gene expression. In this study, we tested the hypotheses that age and clinical attributes of subjects influence in vitro responsiveness of hMSCs to 1,25(OH)(2) D(3) . In a cohort of subjects whose hMSCs were isolated from bone marrow discarded during hip replacement surgery for osteoarthritis, there were significant inverse correlations with age for bone mineral density, renal function, body mass index, fat mass index, and lean mass index (n = 36-53). There were significant correlations with serum 25(OH)D for serum parathyroid hormone (PTH), body mass index, fat mass index, and lean mass index (n = 47-50). In vivo-in vitro correlation analyses indicated that there were significantly greater in vitro effects of 1,25(OH)(2) D(3) to stimulate osteoblast differentiation in hMSCs obtained from subjects who were younger than 65 years of age, or who had serum 25(OH)D ≤ 20 ng/mL, elevated serum PTH, or better renal function, assessed by estimated glomerular filtration rate. The greater in vitro stimulation of osteoblast differentiation by 1,25(OH)(2) D(3) in hMSCs from vitamin D-deficient subjects suggests that vitamin D replenishment may lead to more vigorous bone formation in subjects at risk.

Effects of 4 weight-loss diets differing in fat, protein, and carbohydrate on fat mass, lean mass, visceral adipose tissue, and hepatic fat: results from the POUNDS LOST trial

BACKGROUND

Weight loss reduces body fat and lean mass, but whether these changes are influenced by macronutrient composition of the diet is unclear.

OBJECTIVE

We determined whether energy-reduced diets that emphasize fat, protein, or carbohydrate differentially reduce total, visceral, or hepatic fat or preserve lean mass.

DESIGN

In a subset of participants in a randomized trial of 4 weight-loss diets, body fat and lean mass (n = 424; by using dual-energy X-ray absorptiometry) and abdominal and hepatic fat (n = 165; by using computed tomography) were measured after 6 mo and 2 y. Changes from baseline were compared between assigned amounts of protein (25% compared with 15%) and fat (40% compared with 20%) and across 4 carbohydrate amounts (35% through 65%).

RESULTS

At 6 mo, participants lost a mean (±SEM) of 4.2 ± 0.3 kg (12.4%) fat and 2.1 ± 0.3 kg (3.5%) lean mass (both P < 0.0001 compared with baseline values), with no differences between 25% and 15% protein (P ≥ 0.10), 40% and 20% fat (P ≥ 0.34), or 65% and 35% carbohydrate (P ≥ 0.27). Participants lost 2.3 ± 0.2 kg (13.8%) abdominal fat: 1.5 ± 0.2 kg (13.6%) subcutaneous fat and 0.9 ± 0.1 kg (16.1%) visceral fat (all P < 0.0001 compared with baseline values), with no differences between the diets (P ≥ 0.29). Women lost more visceral fat than did men relative to total-body fat loss. Participants regained ~40% of these losses by 2 y, with no differences between diets (P ≥ 0.23). Weight loss reduced hepatic fat, but there were no differences between groups (P ≥ 0.28). Dietary goals were not fully met; self-reported contrasts were closer to 2% protein, 8% fat, and 14% carbohydrate at 6 mo and 1%, 7%, and 10%, respectively, at 2 y.

CONCLUSION

Participants lost more fat than lean mass after consumption of all diets, with no differences in changes in body composition, abdominal fat, or hepatic fat between assigned macronutrient amounts. This trial was registered at clinicaltrials.gov as NCT00072995.

Forum on aging and skeletal health: summary of the proceedings of an ASBMR workshop

With the aging of the population, the scope of the problem of age-related bone loss and osteoporosis will continue to increase. As such, it is critical to obtain a better understanding of the factors determining the acquisition and loss of bone mass from childhood to senescence. While there have been significant advances in recent years in our understanding of both the basic biology of aging and a clinical definition of age-related frailty, few of these concepts in aging research have been evaluated adequately for their relevance and application to skeletal aging or fracture prevention. The March 2011 Forum on Aging and Skeletal Health, sponsored by the NIH and ASBMR, sought to bring together leaders in aging and bone research to enhance communications among diverse fields of study so as to accelerate the pace of scientific advances needed to reduce the burden of osteoporotic fractures. This report summarizes the major concepts presented at that meeting and in each area identifies key questions to help set the agenda for future research in skeletal aging.

Systems-based approaches to osteoporosis and fracture care: policy and research recommendations from the workgroups

Participants in the conference selected to attend two different working group sessions. The working groups discussed different perspectives of system-based approaches to osteoporosis and fracture care. The group on postfracture case management recommended that nurse case managers be used to improve communication among patients, orthopaedic surgeons, and those providing ongoing clinical care. The hospital working group discussed the impact of and barriers to improved postfracture management in the hospital setting. The health systems group emphasized the difference between a closed system in which long-term benefits of interventions were more likely to be appreciated than in fee for service systems. The health information technology group discussed the advantages and challenges of electronic health records. The working group on consumer and provider education discussed interventions for both primary and secondary prevention of fractures. Recommendations were produced by most groups for improving postfracture care.

Ethnic differences in femur geometry in the women's health initiative observational study

SUMMARY

Participants in the observational study of the Women's Health Initiative (WHI) were studied to determine if ethnic differences in femur geometry can help to explain differences in hip fracture rates. Structural differences in femurs of African and Mexican-American women appear to be consistent with lower rates of hip fractures vs. whites.

INTRODUCTION

Ethnic origin has a major influence on hip fractures, but the underlying etiology is unknown. We evaluated ethnic differences in hip fracture rates among 159,579 postmenopausal participants in the WHI then compared femur bone mineral density (BMD) and geometry among a subset with dual X-ray absorptiometry (DXA) scans of the hip and total body.

METHODS

The subset included 8,206 non-Hispanic whites, 1,476 African-American (AA), 704 Mexican-American (MA), and 130 Native Americans (NA). Femur geometry derived from hip DXA using hip-structure analysis (HSA) in whites was compared to minority groups after adjustment for age, height, weight, percent lean mass, neck-shaft angle and neck length, hormone use, chronic disease (e.g., diabetes, rheumatoid arthritis, cancer), bone active medications (e.g., corticosteroids, osteoporosis therapies), and clinical center.

RESULTS

Both AA and MA women suffered hip fractures at half the rate of whites while NA appeared to be similar to whites. The structural advantage among AA appears to be due to a slightly narrower femur that requires more bone tissue to achieve similar or lower section moduli (SM) vs. whites. This also underlies their higher BMD (reduces region area) and lower buckling ratios (buckling susceptibility). Both MA and NA women had similar advantages vs. whites at the intertrochanter region where cross-sectional area and SM were higher but with no differences at the neck. NA and MA had smaller bending moments vs. whites acting in a fall on the hip (not significant in small NA sample). Buckling ratios of MA did not differ from whites at any region although NA had 4% lower values at the IT region.

CONCLUSION

Differences in the geometry at the proximal femur are consistent with the lower hip fracture rates among AA and MA women compared to whites.

Reduced osteoclastogenesis and RANKL expression in marrow from women taking alendronate

Alendronate (AL) is commonly used for the prevention and treatment of osteoporotic fractures. Little is known about the effects of AL administration on osteoclast differentiation from human marrow progenitor cells. We used marrow discarded during orthopedic surgery to test the hypothesis that cultures of bone marrow-derived stem cells (BMCs) from subjects receiving AL (+AL) may differ from control subjects with respect to in vitro osteoclast differentiation and regulatory factors. The number of osteoclasts generated in BMC cultures from control subjects was 4.7-fold greater than that from +AL subjects (P = 0.015). RANKL expression in +AL BMCs was 57% of that in controls (P = 0.001), and OPG expression in +AL BMCs was greater than in controls (153%, P = 0.01). The mean RANKL/OPG ratio in BMCs was 0.65 ± 0.35 for +AL specimens and 1.28 ± 0.53 for controls (P = 0.031). In addition, we assessed the direct effect of AL on expression of RANKL and OPG in marrow stromal cells isolated from nine control women. Treatment with AL downregulated RANKL expression and upregulated OPG expression, with an average 50% decrease in RANKL/OPG ratio at 10(-7) M (P = 0.004). These results show that osteoclast differentiation is dysregulated in marrow isolated from +AL subjects. Furthermore, AL may inhibit human osteoclastogenesis by affecting the key regulatory genes in marrow cells.

Calcium plus vitamin D supplementation has limited effects on femoral geometric strength in older postmenopausal women: the Women's Health Initiative

Calcium plus vitamin D (CaD) supplementation has a modest but significant effect on slowing loss of femoral bone mass and reducing risk of hip fractures in adherent postmenopausal women. The goal of this study was to determine if CaD supplementation influences hip structural parameters that are associated with fracture risk. We studied 1,970 postmenopausal women enrolled in the Women's Health Initiative randomized controlled trial of CaD at one of three bone mineral density (BMD) clinical centers. Hip structural analysis software measured BMD and strength parameters on DXA scans at three regions: femoral narrow neck, intertrochanter, and shaft. Random effects models were used to test the average differences in hip BMD and geometry between intervention and placebo. There was greater preservation of hip BMD at the narrow neck with CaD relative to placebo across 6 years of intervention. CaD also altered the underlying cross-sectional geometry at the narrow neck in the direction of greater strength, with small increases in cross-sectional area and section modulus and a decrease in buckling ratio with CaD relative to placebo. While trends at both the intertrochanter and shaft regions were similar to those noted at the narrow neck, no significant intervention effects were evident. There was no significant interaction of CaD and age or baseline calcium levels for hip structural properties. CaD supplementation is associated with modest beneficial effects on hip structural features at the narrow neck, which may explain some of the benefit of CaD in reducing hip fracture risk.

Predictors of serum 25-hydroxyvitamin D concentrations among postmenopausal women: the Women's Health Initiative Calcium plus Vitamin D clinical trial

BACKGROUND

It is unclear how well surrogate markers for vitamin D exposure (eg, oral intake of vitamin D and estimates of sunlight exposure), with and without consideration of other potential predictors of 25-hydroxyvitamin D [25(OH)D] concentrations, similarly rank individuals with respect to 25(OH)D blood concentrations.

OBJECTIVE

The objective was to determine how much variation in serum 25(OH)D concentrations (nmol/L) could be explained by a predictive model with the use of different vitamin D surrogate markers (latitude of residence, mean annual regional solar irradiance estimates, and oral sources) and other individual characteristics that might influence vitamin D status.

DESIGN

A random sample of 3055 postmenopausal women (aged 50-70 y) participating in 3 nested case-control studies of the Women's Health Initiative Calcium plus Vitamin D Clinical Trial was used. Serum 25(OH)D values, assessed at year 1 (1995-2000), and potential predictors of 25(OH)D concentrations, assessed at year 1 or Women's Health Initiative baseline (1993-1998), were used.

RESULTS

More than half of the women (57.1%) had deficient (<50 nmol/L) concentrations of 25(OH)D. Distributions of 25(OH)D concentrations by level of latitude of residence, mean annual regional solar irradiance, and intake of vitamin D varied considerably. The predictive model for 25(OH)D explained 21% of the variation in 25(OH)D concentrations. After adjustment for month of blood draw, breast cancer status, colorectal cancer status, fracture status, participation in the hormone therapy trial, and randomization to the dietary modification trial, the predictive model included total vitamin D intake from foods and supplements, waist circumference, recreational physical activity, race-ethnicity, regional solar irradiance, and age.

CONCLUSIONS

Surrogate markers for 25(OH)D concentrations, although somewhat correlated, do not adequately reflect serum vitamin D measures. These markers and predictive models of blood 25(OH)D concentrations should not be given as much weight in epidemiologic studies of cancer risk.