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Bess Dawson-Hughes

Publications and source records attributed to Bess Dawson-Hughes.

At least 19 recordsLinked to original sources
PubMed2007

Incidence and economic burden of osteoporosis-related fractures in the United States, 2005-2025.

UNLABELLED: This study predicts the burden of incident osteoporosis-related fractures and costs in the United States, by sex, age group, race/ethnicity, and fracture type, from 2005 to 2025. Total fractures were >2 million, costing nearly $17 billion in 2005. Men account for >25% of the burden. Rapid growth in the disease burden is projected among nonwhite populations. INTRODUCTION: The aging of the U.S. population will likely lead to greater prevalence of osteoporosis. Policy makers require precise projections of the disease burden by demographic subgroups and skeletal sites to effectively target osteoporosis intervention and treatment programs. MATERIALS AND METHODS: A state transition Markov decision model was used to estimate total incident fractures and costs by age, sex, race/ethnicity, and skeletal site for the U.S. population 50 years of age for 2005-2025. RESULTS: More than 2 million incident fractures at a cost of $17 billion are predicted for 2005. Total costs including prevalent fractures are more than $19 billion. Men account for 29% of fractures and 25% of costs. Total incident fractures by skeletal site were vertebral (27%), wrist (19%), hip (14%), pelvic (7%), and other (33%). Total costs by fracture type were vertebral (6%), hip (72%), wrist (3%), pelvic (5%), and other (14%). By 2025, annual fractures and costs are projected to rise by almost 50%. The most rapid growth is estimated for people 65-74 years of age, with an increase>87%. An increase of nearly 175% is projected for Hispanic and other subpopulations. CONCLUSIONS: Osteoporosis prevention, treatment, and education efforts should address all skeletal sites, not just hip and vertebral, and appropriate attention is warranted for men and diverse race/ethnicity subgroups.

Cost of Illness↗
PubMed2006

Matrix Gla protein is associated with risk factors for atherosclerosis but not with coronary artery calcification.

OBJECTIVE: Atherosclerotic coronary artery calcification (CAC) is associated with increased coronary heart disease (CHD) risk. Matrix Gla protein (MGP) is an inhibitor of calcification in vivo. However, little is known regarding the distribution of circulating MGP and its associations with CHD risk factors or with CAC in humans. METHODS AND RESULTS: Serum MGP concentrations were determined in 2 independent populations of men and women free of clinically apparent cardiovascular disease: study A, n=316, mean age 58 years, and study B, n=452, mean age 68 years. CAC was determined by computed tomography. Mean MGP concentrations were 98.4 and 198 ng/mL in men, and 97.4 and 201 ng/mL in women, in study A and study B, respectively. In both cohorts, MGP levels were higher with increasing age. In age-adjusted analyses, there was an association of circulating MGP with increasing Framingham CHD risk score (in study A, P=0.003 in men and P=0.016 in women, respectively; in study B, a nonsignificant increase in men and P=0.05 in women, respectively). Significant associations of circulating MGP with high-density lipoprotein and other individual CHD risk factors were also noted in both cohorts. There were no consistent associations between MGP and CAC after adjustment for CHD risk score in the 2 cohorts. CONCLUSIONS: MGP is associated with individual CHD risk factors and the Framingham CHD risk score in men and women free of clinically apparent CHD. The relation of MGP with CAC deserves further study in larger populations.

Adult↗
PubMed2006

Effect of cholecalciferol plus calcium on falling in ambulatory older men and women: a 3-year randomized controlled trial.

BACKGROUND: A recent meta-analysis found that cholecalciferol (vitamin D) should reduce falls by more than 20%. However, little is known about whether supplemental cholecalciferol plus calcium citrate malate will lower the long-term risk of falling in men, active older individuals, and older individuals with higher 25-hydroxyvitamin D levels. METHODS: We studied the effect of 3-year supplementation with cholecalciferol-calcium on the risk of falling at least once in 199 men and 246 women 65 years or older and living at home. Individuals received 700 IU of cholecalciferol plus 500 mg of calcium citrate malate per day or placebo in a randomized double-blind manner. Subjects were classified as less physically active if physical activity was below the median level. Low 25-hydroxyvitamin D levels were classified as those below 32 ng/mL (<80 nmol/L). RESULTS: In 3 years, 55% of women and 45% of men reported at least 1 fall. Mean +/- SD baseline 25-hydroxyvitamin D levels were 26.6 +/- 12.7 ng/mL (66.4 +/- 31.7 nmol/L) in women and 33.2 +/- 14.2 ng/mL (82.9 +/- 34.9) in men. Cholecalciferol-calcium significantly reduced the odds of falling in women (odds ratio [OR], 0.54; 95% confidence interval [CI], 0.30-0.97), but not in men (OR, 0.93; 95% CI, 0.50-1.72). Fall reduction was most pronounced in less active women (OR, 0.35; 95% CI, 0.15-0.81). Baseline 25-hydroxyvitamin D level did not modulate the treatment effect. CONCLUSIONS: Long-term dietary cholecalciferol-calcium supplementation reduces the odds of falling in ambulatory older women by 46%, and especially in less active women by 65%. Supplementation had a neutral effect in men independent of their physical activity level.

Accidental Falls↗
PubMed2006

Preventing osteoporosis-related fractures: an overview.

Osteoporosis is a skeletal disorder characterized by compromised bone strength, which predisposes a person to increased risk of fracture. In the United States, 26% of women aged > or =65 years and >50% of women aged > or =85 years have osteoporosis. Over 1.5 million fractures per year are attributable to osteoporosis; these fractures result in 500,000 hospitalizations, 800,000 emergency room visits, 2.6 million physician visits, 180,000 nursing home placements, and 12 billion dollars to 18 billion dollars in direct healthcare costs each year. Fracture also results in loss of function and has a negative impact on psychological status. In recognition of the importance of bone health, the US Surgeon General has, for the first time, issued a comprehensive report on bone health and treatment. The report recommends a pyramidal approach to osteoporosis treatment that includes calcium and vitamin D supplementation, physical activity, and fall prevention as the first line in fracture prevention. The second level consists of treating secondary causes of osteoporosis; the third and top level consists of pharmacotherapy. Pharmacotherapeutic interventions (e.g., bisphosphonates, selective estrogen receptor modulators, calcitonin, and teriparatide) in women with postmenopausal osteoporosis provide substantial reduction in fracture risk over and above risk reduction with calcium and vitamin D supplementation alone. Despite the effectiveness of therapy, most patients who receive treatment do not remain on treatment for >1 year. An important approach to reducing the rate of fractures is first to target our treatments to patients at high risk for fracture and then to develop strategies to improve treatment continuation rates.

Absorptiometry, Photon↗
PubMed2006

Dietary acid-base balance, bone resorption, and calcium excretion.

OBJECTIVE: Metabolic studies reveal that acidogenic diets increase bone resorption acutely. This study was conducted to examine associations between diet-induced changes in net acid excretion (NAE) and changes in serum parathyroid hormone (PTH), bone resorption, and calcium excretion over a longer period of 60 days. METHODS: Forty healthy older men and women were given 0.75 g/kg of protein as meat, 600 mg of calcium, and 400 IU of vitamin D3 daily and either cereal (acidogenic) or fruit and vegetable (alkalinogenic) foods as substitutes for some of the cereal in their usual diets. Blood and 24-hr urine measurements were made on days 14 (baseline), 44, and 74. RESULTS: In all subjects, change in renal NAE was correlated with changes in serum PTH (r = 0.358, P = 0.023), urinary N-telopeptide (NTX) (r = 0.367, P = 0.020), and urinary calcium excretion (rp = 0.381, P = 0.020, after adjustment for diet group, change in PTH, and change in sodium excretion). CONCLUSIONS: Diet changes that increase renal NAE are associated with increases in serum PTH, bone resorption, and calcium excretion over a 60-day period.

Acid-Base Equilibrium↗
PubMed2006

Estimation of optimal serum concentrations of 25-hydroxyvitamin D for multiple health outcomes.

Recent evidence suggests that vitamin D intakes above current recommendations may be associated with better health outcomes. However, optimal serum concentrations of 25-hydroxyvitamin D [25(OH)D] have not been defined. This review summarizes evidence from studies that evaluated thresholds for serum 25(OH)D concentrations in relation to bone mineral density (BMD), lower-extremity function, dental health, and risk of falls, fractures, and colorectal cancer. For all endpoints, the most advantageous serum concentrations of 25(OH)D begin at 75 nmol/L (30 ng/mL), and the best are between 90 and 100 nmol/L (36-40 ng/mL). In most persons, these concentrations could not be reached with the currently recommended intakes of 200 and 600 IU vitamin D/d for younger and older adults, respectively. A comparison of vitamin D intakes with achieved serum concentrations of 25(OH)D for the purpose of estimating optimal intakes led us to suggest that, for bone health in younger adults and all studied outcomes in older adults, an increase in the currently recommended intake of vitamin D is warranted. An intake for all adults of > or =1000 IU (25 microg) [DOSAGE ERROR CORRECTED] vitamin D (cholecalciferol)/d is needed to bring vitamin D concentrations in no less than 50% of the population up to 75 nmol/L. The implications of higher doses for the entire adult population should be addressed in future studies.

Age Factors↗
PubMed2006

Vitamin D and calcium intake in relation to type 2 diabetes in women.

OBJECTIVE: The purpose of this study was to prospectively examine the association between vitamin D and calcium intake and risk of type 2 diabetes. RESEARCH DESIGN AND METHODS: In the Nurses' Health Study, we followed 83,779 women who had no history of diabetes, cardiovascular disease, or cancer at baseline for the development of type 2 diabetes. Vitamin D and calcium intake from diet and supplements was assessed every 2-4 years. During 20 years of follow-up, we documented 4,843 incident cases of type 2 diabetes. RESULTS: After adjusting for multiple potential confounders, there was no association between total vitamin D intake and type 2 diabetes. However, the relative risk (RR) of type 2 diabetes was 0.87 (95% CI 0.75-1.00; P for trend = 0.04) comparing the highest with the lowest category of vitamin D intake from supplements. The multivariate RRs of type 2 diabetes were 0.79 (0.70-0.90; P for trend <0.001) comparing the highest with the lowest category of calcium intake from all sources and 0.82 (0.72-0.92; P for trend <0.001) comparing the highest with the lowest category of calcium intake from supplements. A combined daily intake of >1,200 mg calcium and >800 IU vitamin D was associated with a 33% lower risk of type 2 diabetes with RR of 0.67 (0.49-0.90) compared with an intake of <600 mg and 400 IU calcium and vitamin D, respectively. CONCLUSIONS: The results of this large prospective study suggest a potential beneficial role for both vitamin D and calcium intake in reducing the risk of type 2 diabetes.

Adult↗
PubMed2005

Childhood overweight and maturational timing in the development of adult overweight and fatness: the Newton Girls Study and its follow-up.

OBJECTIVE: Although several studies have suggested that early menarche is associated with the development of adult overweight, few have accounted for childhood overweight before menarche. STUDY DESIGN: A 30-year follow-up of the original participants in the Newton Girls Study, a prospective study of development in a cohort of girls followed through menarche, provided data on premenarcheal relative weight and overweight (BMI >85th percentile), prospectively obtained age at menarche, self-reported adult BMI, overweight (BMI > 25), obesity (BMI > 30) and, for a subset of participants, percentage body fat by dual-energy x-ray absorptiometry. RESULTS: Of the 448 women who participated in the adult follow-up at a mean age of 42.1 years (SD: 0.76 years), 307 had childhood data with which to characterize premenarcheal and menarcheal weight status and age at menarche. After a follow-up of 30.1 years (SD: 1.4 years), reported BMI was 23.4 (4.8), 28% were overweight, and 9% were obese. In multivariate linear and logistic-regression analyses, almost all of the influence on adult weight status was a result of premenarcheal weight status (model R2 = 0.199). Inclusion of a variable to reflect menarcheal timing provided very little additional information (model R2 = 0.208). Girls who were overweight before menarche were 7.7 times more likely to be overweight as adults (95% confidence interval: 2.3, 25.8), whereas early menarche (at < or = 12 years of age) did not elevate risk (odds ratio: 1.3, 95% confidence interval: 0.66, 2.43). A similar pattern of results was observed when percentage body fat in adulthood was evaluated. CONCLUSIONS: The apparent influence of early maturation on adult female overweight is largely a result of the influence of elevated relative weight on early maturation. Interventions to prevent and treat overweight should focus on girls before they begin puberty.

Adult↗
PubMed2005

Fracture prevention with vitamin D supplementation: a meta-analysis of randomized controlled trials.

CONTEXT: The role and dose of oral vitamin D supplementation in nonvertebral fracture prevention have not been well established. OBJECTIVE: To estimate the effectiveness of vitamin D supplementation in preventing hip and nonvertebral fractures in older persons. DATA SOURCES: A systematic review of English and non-English articles using MEDLINE and the Cochrane Controlled Trials Register (1960-2005), and EMBASE (1991-2005). Additional studies were identified by contacting clinical experts and searching bibliographies and abstracts presented at the American Society for Bone and Mineral Research (1995-2004). Search terms included randomized controlled trial (RCT), controlled clinical trial, random allocation, double-blind method, cholecalciferol, ergocalciferol, 25-hydroxyvitamin D, fractures, humans, elderly, falls, and bone density. STUDY SELECTION: Only double-blind RCTs of oral vitamin D supplementation (cholecalciferol, ergocalciferol) with or without calcium supplementation vs calcium supplementation or placebo in older persons (> or =60 years) that examined hip or nonvertebral fractures were included. DATA EXTRACTION: Independent extraction of articles by 2 authors using predefined data fields, including study quality indicators. DATA SYNTHESIS: All pooled analyses were based on random-effects models. Five RCTs for hip fracture (n = 9294) and 7 RCTs for nonvertebral fracture risk (n = 9820) met our inclusion criteria. All trials used cholecalciferol. Heterogeneity among studies for both hip and nonvertebral fracture prevention was observed, which disappeared after pooling RCTs with low-dose (400 IU/d) and higher-dose vitamin D (700-800 IU/d), separately. A vitamin D dose of 700 to 800 IU/d reduced the relative risk (RR) of hip fracture by 26% (3 RCTs with 5572 persons; pooled RR, 0.74; 95% confidence interval [CI], 0.61-0.88) and any nonvertebral fracture by 23% (5 RCTs with 6098 persons; pooled RR, 0.77; 95% CI, 0.68-0.87) vs calcium or placebo. No significant benefit was observed for RCTs with 400 IU/d vitamin D (2 RCTs with 3722 persons; pooled RR for hip fracture, 1.15; 95% CI, 0.88-1.50; and pooled RR for any nonvertebral fracture, 1.03; 95% CI, 0.86-1.24). CONCLUSIONS: Oral vitamin D supplementation between 700 to 800 IU/d appears to reduce the risk of hip and any nonvertebral fractures in ambulatory or institutionalized elderly persons. An oral vitamin D dose of 400 IU/d is not sufficient for fracture prevention.

Aged↗
PubMed2005

Estimates of optimal vitamin D status.

Vitamin D has captured attention as an important determinant of bone health, but there is no common definition of optimal vitamin D status. Herein, we address the question: What is the optimal circulating level of 25-hydroxyvitamin D [25(OH)D] for the skeleton? The opinions of the authors on the minimum level of serum 25(OH)D that is optimal for fracture prevention varied between 50 and 80 nmol/l. However, for five of the six authors, the minimum desirable 25(OH)D concentration clusters between 70 and 80 nmol/l. The authors recognize that the average older man and woman will need intakes of at least 20 to 25 mcg (800 to 1,000 IU) per day of vitamin D(3 )to reach a serum 25(OH)D level of 75 nmol/l. Based on the available evidence, we believe that if older men and women maintain serum levels of 25(OH)D that are higher than the consensus median threshold of 75 nmol/l, they will be at lower risk of fracture.

Adult↗
PubMed2005

Association between serum concentrations of 25-hydroxyvitamin D and gingival inflammation.

BACKGROUND: Vitamin D has been shown to have immunomodulatory effects in in vitro and in animal studies. However, data from clinical studies of inflammatory diseases are scarce. OBJECTIVE: The purpose of this study was to evaluate the association between serum concentrations of 25-hydroxyvitamin D [25(OH)D] and gingival inflammation. DESIGN: We analyzed data from 77,503 gingival units (teeth) in 6700 never smokers aged 13 to >90 y from the third National Health and Nutrition Examination Survey. Multiple logistic regression models adjusted for subject- and site-specific covariates included age, sex, race-ethnicity, income, body mass index, diabetes, use of oral contraceptives and hormone replacement therapy among women, intake of vitamin C, missing teeth, full crown coverage, presence of calculus, frequency of dental visits, and dental examiner and survey phase. Generalized estimating equations were used to account for correlated observations within subjects. RESULTS: Compared with sites in subjects in the lowest 25(OH)D quintile, sites in subjects in the highest 25(OH)D quintile were 20% (95% CI: 8%, 31%) less likely to bleed on gingival probing (P for trend < 0.001). The association appeared to be linear over the entire 25(OH)D range, was consistent across racial or ethnic groups, and was similar among men and women as well as among users and nonusers of vitamin and mineral supplements. CONCLUSIONS: Vitamin D may reduce susceptibility to gingival inflammation through its antiinflammatory effects. Gingivitis may be a useful clinical model to evaluate the antiinflammatory effects of vitamin D.

Adolescent↗
PubMed2004

Lack of effect of calcium intake on the 25-hydroxyvitamin d response to oral vitamin D3.

This study was conducted to examine the effect of calcium intake on the rise in serum 25-hydroxyvitamin D [25(OH)D] levels in response to supplemental vitamin D(3). Fifty-two healthy older men and women were randomly assigned to take calcium (500 mg twice daily with meals) or placebo tablets for 90 d between October 1 and the end of March. All participants were placed on 800 IU/d (20 microg/d) vitamin D(3). Serum 25(OH)D measurements were made at baseline and on d 30, 60, and 90. The mean baseline 25(OH)D values were 19.2 +/- 6.4 ng/ml (47.9 +/- 15.9 nmol/liter) in the calcium group and 19.6 +/- 6.7 ng/ml (49.1 +/- 16.7 nmol/liter) in the control group (P = 0.808). The difference in pattern of change in 25(OH)D was not statistically significant (group by time interaction, P = 0.651); the calcium group increased 6.5 +/- 5.9 ng/ml (16.2 +/- 14.8 nmol/liter; P < 0.001), and the control group increased 6.6 +/- 7.0 ng/ml (16.6 +/- 17.4 nmol/liter; P < 0.001). The 95% confidence interval for difference in mean increase, calcium vs. control, was -3.8 +/- 3.5 ng/ml (-9.6, 8.7) nmol/liter. In older men and women, the level of calcium intake, within the range of 500-1500 mg/d, does not have an important effect on the rise in serum 25(OH)D that occurs in response to 800 IU (20 microg)/d vitamin D(3).

Aged↗
PubMed2004

Calcium supplement and osteoporosis medication use in women and men with recent fractures.

Patients with low-trauma fractures are at risk of future fractures and so should be evaluated and treated for osteoporosis. This study was conducted to assess and compare bone medication use and calcium and vitamin D intake at the time of and after an acute fracture. One hundred and six patients, mean age 66.7+/-10.3 years, were administered medical history and diet questionnaires at enrollment (in an urban hospital) and again 6 and 12 months later (by telephone). Of 86 patients who could be contacted 6 months after their fracture, 36.2% of the women and 7.4% of the men had recently discussed osteoporosis with their primary care doctor. At 6 months, 24.2% of the women and 3.6% of the men were taking bone medications (compared with 27.8% and 3.6% before the fracture; NS). At 6 months, 52.6% of the women and 10.7% of the men indicated that their doctor had recently recommended calcium or vitamin D. Among the women who had recently been advised by their primary care doctor to use calcium or vitamin D, supplement use increased from 63.3% to 90.0% (P = 0.021) and dairy food intake increased from 1.5+/-1.1 to 2.4+/-1.9 servings/day (P = 0.016). Only three men received this advice and two of them heeded it. Among women and men not receiving this advice, there was no significant increase in calcium supplement use or dairy food intake. At 12 months, the treatment profiles were unchanged from 6 months and 9.6% of the women and 4.3% of the men had had another fracture. In conclusion, the occurrence of a fracture did not increase likelihood of pharmacologic treatment for osteoporosis. After their fractures, the women did increase their intake of calcium supplements and dairy foods when this was recommended by their doctor. This suggests that the primary care physician is well positioned to bring about much needed change in the quality of care of fracture patients.

Aged↗
PubMed2004

Effect of Vitamin D on falls: a meta-analysis.

CONTEXT: Falls among elderly individuals occur frequently, increase with age, and lead to substantial morbidity and mortality. The role of vitamin D in preventing falls among elderly people has not been well established. OBJECTIVE: To assess the effectiveness of vitamin D in preventing an older person from falling. DATA SOURCES: MEDLINE and the Cochrane Controlled Trials Register from January 1960 to February 2004, EMBASE from January 1991 to February 2004, clinical experts, bibliographies, and abstracts. Search terms included trial terms: randomized-controlled trial or controlled-clinical trial or random-allocation or double-blind method, or single-blind method or uncontrolled-trials with vitamin D terms: cholecalciferol or hydroxycholecalciferols or calcifediol or dihydroxycholecalciferols or calcitriol or vitamin D/aa[analogs & derivates] or ergocalciferol or vitamin D/bl[blood]; and with accidental falls or falls, and humans. STUDY SELECTION: We included only double-blind randomized, controlled trials (RCTs) of vitamin D in elderly populations (mean age, 60 years) that examined falls resulting from low trauma for which the method of fall ascertainment and definition of falls were defined explicitly. Studies including patients in unstable health states were excluded. Five of 38 identified studies were included in the primary analysis and 5 other studies were included in a sensitivity analysis. DATA EXTRACTION: Independent extraction by 3 authors using predefined data fields including study quality indicators. DATA SYNTHESIS: Based on 5 RCTs involving 1237 participants, vitamin D reduced the corrected odds ratio (OR) of falling by 22% (corrected OR, 0.78; 95% confidence interval [CI], 0.64-0.92) compared with patients receiving calcium or placebo. From the pooled risk difference, the number needed to treat (NNT) was 15 (95% CI, 8-53), or equivalently 15 patients would need to be treated with vitamin D to prevent 1 person from falling. The inclusion of 5 additional studies, involving 10 001 participants, in a sensitivity analysis resulted in a smaller but still significant effect size (corrected RR, 0.87; 95% CI, 0.80-0.96). Subgroup analyses suggested that the effect size was independent of calcium supplementation, type of vitamin D, duration of therapy, and sex, but reduced sample sizes made the results statistically nonsignificant for calcium supplementation, cholecalciferol, and among men. CONCLUSIONS: Vitamin D supplementation appears to reduce the risk of falls among ambulatory or institutionalized older individuals with stable health by more than 20%. Further studies examining the effect of alternative types of vitamin D and their doses, the role of calcium supplementation, and effects in men should be considered.

Accidental Falls↗
PubMed2004

Association between serum concentrations of 25-hydroxyvitamin D3 and periodontal disease in the US population.

BACKGROUND: Periodontal disease (PD) is a common chronic inflammatory disease and an important risk factor for tooth loss. Vitamin D might affect periodontal disease risk via an effect on bone mineral density (BMD) or via immunomodulatory effects. OBJECTIVE: The objective was to evaluate whether serum 25-hydroxyvitamin D(3) [25(OH)D(3)] concentrations are associated with PD in the third National Health and Nutrition Examination Survey. DESIGN: We analyzed data on periodontal attachment loss (AL) and serum 25(OH)D(3) concentrations from 11 202 subjects aged > or =20 y. Mean AL was modeled in a multiple linear regression with quintile of serum 25(OH)D(3) concentration as an independent variable. The model was stratified by age and sex and was adjusted for age within age groups, race or ethnicity, smoking, diabetes, poverty income ratio, body mass index, estrogen use, and gingival bleeding. RESULTS: 25(OH)D(3) concentrations were significantly and inversely associated with AL in men and women aged > or =50 y. Compared with men in the highest 25(OH)D(3) quintile, those in the lowest quintile had a mean AL that was 0.39 mm (95% CI: 0.17, 0.60 mm) higher; in women, the difference in AL between the lowest and highest quintiles was 0.26 mm (0.09, 0.43 mm). In men and women younger than 50 y, there was no significant association between 25(OH)D(3) and AL. The BMD of the total femoral region was not associated with AL and did not mediate the association between 25(OH)D(3) and AL. CONCLUSIONS: Low serum 25(OH)D(3) concentrations may be associated with PD independently of BMD. Given the high prevalence of PD and vitamin D deficiency, these findings may have important public health implications.

Adult↗
PubMed2004

Higher 25-hydroxyvitamin D concentrations are associated with better lower-extremity function in both active and inactive persons aged > or =60 y.

BACKGROUND: Vitamin D may improve muscle strength through a highly specific nuclear receptor in muscle tissue. OBJECTIVES: We investigated whether there is an association between 25-hydroxyvitamin D [25(OH)D] concentrations and lower-extremity function in ambulatory older persons, whether that association differs by activity level, and, if so, whether there is an identifiable threshold in the association. DESIGN: The study was a population-based survey of the ambulatory US population aged 60 to > or =90 y (n = 4100). Lower-extremity function according to serum 25(OH)D concentrations was assessed by linear regression analyses and regression plots after control for activity level (inactive or active) and several other potential confounders. Separate analyses were performed for the timed 8-foot (ie, 2.4 m) walk test and a repeated sit-to-stand test. RESULTS: The 8-foot walk test compared subjects in the lowest and highest quintiles of 25(OH)D; the latter group had an average decrease of 0.27 s [95% CI: -0.44, -0.09 s (or 5.6%); P for trend < 0.001]. The sit-to-stand test compared subjects in the lowest and highest quintiles of 25(OH)D; the latter group had an average decrease of 0.67 s [95% CI: -1.11, -0.23 s (or 3.9%); P for trend = 0.017]. In the 25(OH)D reference range of 22.5-94 nmol/L, most of the improvement occurred in subjects with 25(OH)D concentrations between 22.5 and approximately 40 nmol/L, and further improvement was seen in the range of 40-94 nmol/L. Stratification by activity level showed no significant effect modification. CONCLUSION: In both active and inactive ambulatory persons aged > or =60 y, 25(OH)D concentrations between 40 and 94 nmol/L are associated with better musculoskeletal function in the lower extremities than are concentrations < 40 nmol/L.

Aged↗