Last data update: Nov 04, 2024. (Total: 48056 publications since 2009)
Records 1-28 (of 28 Records) |
Query Trace: Looker AC[original query] |
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Laboratory methodologies for indicators of iron status: strengths, limitations, and analytical challenges
Pfeiffer CM , Looker AC . Am J Clin Nutr 2017 106 1606s-1614s Biochemical assessment of iron status relies on serum-based indicators, such as serum ferritin (SF), transferrin saturation, and soluble transferrin receptor (sTfR), as well as erythrocyte protoporphyrin. These indicators present challenges for clinical practice and national nutrition surveys, and often iron status interpretation is based on the combination of several indicators. The diagnosis of iron deficiency (ID) through SF concentration, the most commonly used indicator, is complicated by concomitant inflammation. sTfR concentration is an indicator of functional ID that is not an acute-phase reactant, but challenges in its interpretation arise because of the lack of assay standardization, common reference ranges, and common cutoffs. It is unclear which indicators are best suited to assess excess iron status. The value of hepcidin, non-transferrin-bound iron, and reticulocyte indexes is being explored in research settings. Serum-based indicators are generally measured on fully automated clinical analyzers available in most hospitals. Although international reference materials have been available for years, the standardization of immunoassays is complicated by the heterogeneity of antibodies used and the absence of physicochemical reference methods to establish "true" concentrations. From 1988 to 2006, the assessment of iron status in NHANES was based on the multi-indicator ferritin model. However, the model did not indicate the severity of ID and produced categorical estimates. More recently, iron status assessment in NHANES has used the total body iron stores (TBI) model, in which the log ratio of sTfR to SF is assessed. Together, sTfR and SF concentrations cover the full range of iron status. The TBI model better predicts the absence of bone marrow iron than SF concentration alone, and TBI can be analyzed as a continuous variable. Additional consideration of methodologies, interpretation of indicators, and analytic standardization is important for further improvements in iron status assessment. |
Trends in osteoporosis and low bone mass in older US adults, 2005-2006 through 2013-2014
Looker AC , Sarafrazi Isfahani N , Fan B , Shepherd JA . Osteoporos Int 2017 28 (6) 1979-1988 This study examined trends in osteoporosis and low bone mass in older US adults between 2005 and 2014 using bone mineral density (BMD) data from the National Health and Nutrition Examination Survey (NHANES). Osteoporosis and low bone mass appear to have increased at the femur neck but not at the lumbar spine during this period. INTRODUCTION: Recent preliminary data from Medicare suggest that the decline in hip fracture incidence among older US adults may have plateaued in 2013-2014, but comparable data on BMD trends for this time period are currently lacking. This study examined trends in the prevalence of osteoporosis and low bone mass since 2005 using BMD data from NHANES. The present study also updated prevalence estimates to 2013-2014 and included estimates for non-Hispanic Asians. METHODS: Femur neck and lumbar spine BMD by DXA were available for 7954 adults aged 50 years and older from four NHANES survey cycles between 2005-2006 and 2013-2014. RESULTS: Significant trends (quadratic or linear) were observed for the femur neck (mean T-score and osteoporosis in both sexes; low bone mass in women) but not for the lumbar spine. The trend in femur neck status was somewhat U-shaped, with prevalences being most consistently significantly higher (by 1.1-6.6 percentage points) in 2013-2014 than 2007-2008. Adjusting for changes in body mass index, smoking, milk intake, and physician's diagnosis of osteoporosis between surveys did not change femur neck trends. In 2013-2014, the percent of older adults with osteoporosis was 6% at the femur neck, 8% at the lumbar spine, and 11% at either site. CONCLUSIONS: There was some evidence of a decline in femur neck BMD between 2005-2006 and 2013-2014, but not in lumbar spine BMD. Changes in the risk factors that could be examined did not explain the femur neck BMD trends. |
Spine fracture prevalence in a nationally representative sample of US women and men aged ≥40 years: results from the National Health and Nutrition Examination Survey (NHANES) 2013-2014
Cosman F , Krege JH , Looker AC , Schousboe JT , Fan B , Sarafrazi Isfahani N , Shepherd JA , Krohn KD , Steiger P , Wilson KE , Genant HK . Osteoporos Int 2017 28 (6) 1857-1866 Spine fracture prevalence is similar in men and women, increasing from <5 % in those <60 to 11 % in those 70-79 and 18 % in those ≥80 years. Prevalence was higher with age, lower bone mineral density (BMD), and in those meeting criteria for spine imaging. Most subjects with spine fractures were unaware of them. INTRODUCTION: Spine fractures have substantial medical significance but are seldom recognized. This study collected contemporary nationally representative spine fracture prevalence data. METHODS: Cross-sectional analysis of 3330 US adults aged ≥40 years participating in NHANES 2013-2014 with evaluable Vertebral Fracture Assessment (VFA). VFA was graded by semiquantitative measurement. BMD and an osteoporosis questionnaire were collected. RESULTS: Overall spine fracture prevalence was 5.4 % and similar in men and women. Prevalence increased with age from <5 % in those <60 to 11 % in those 70-79 and 18 % in those ≥80 years. Fractures were more common in non-Hispanic whites and in people with lower body mass index and BMD. Among subjects with spine fracture, 26 % met BMD criteria for osteoporosis. Prevalence was higher in subjects who met National Osteoporosis Foundation (NOF) criteria for spine imaging (14 vs 4.7 %, P < 0.001). Only 8 % of people with a spine fracture diagnosed by VFA had a self-reported fracture, and among those who self-reported a spine fracture, only 21 % were diagnosed with fracture by VFA. CONCLUSION: Spine fracture prevalence is similar in women and men and increases with age and lower BMD, although most subjects with spine fracture do not meet BMD criteria for osteoporosis. Since most (>90 %) individuals were unaware of their spine fractures, lateral spine imaging is needed to identify these women and men. Spine fracture prevalence was threefold higher in individuals meeting NOF criteria for spine imaging ( approximately 1 in 7 undergoing VFA). Identifying spine fractures as part of comprehensive risk assessment may improve clinical decision making. |
The vitamin D status of the US population from 1988 to 2010 using standardized serum concentrations of 25-hydroxyvitamin D shows recent modest increases
Schleicher RL , Sternberg MR , Lacher DA , Sempos CT , Looker AC , Durazo-Arvizu RA , Yetley EA , Chaudhary-Webb M , Maw KL , Pfeiffer CM , Johnson CL . Am J Clin Nutr 2016 104 (2) 454-61 BACKGROUND: Temporal trends in the US population's vitamin D status have been uncertain because of nonstandardized serum 25-hydroxyvitamin D [25(OH)D] measurements. OBJECTIVE: To accurately assess vitamin D status trends among those aged ≥12 y, we used data from the cross-sectional NHANESs. DESIGN: A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for measuring 25(OH)D (sum of 25-hydroxyvitamin D2 and 25-hydroxyvitamin D3), calibrated to standard reference materials, was used to predict LC-MS/MS-equivalent concentrations from radioimmunoassay data (1988-2006 surveys; n = 38,700) and to measure LC-MS/MS concentrations (2007-2010 surveys; n = 12,446). Weighted arithmetic means and the prevalence of 25(OH)D above or below cutoff concentrations were calculated to evaluate long-term trends. RESULTS: Overall, mean predicted 25(OH)D showed no time trend from 1988 to 2006, but during 2007-2010 the mean measured 25(OH)D was 5-6 nmol/L higher. Those groups who showed the largest 25(OH)D increases (7-11 nmol/L) were older, female, non-Hispanic white, and vitamin D supplement users. During 1988-2010, the proportions of persons with 25(OH)D <40 nmol/L were 14-18% (overall), 46-60% (non-Hispanic blacks), 21-28% (Mexican Americans), and 6-10% (non-Hispanic whites). CONCLUSIONS: An accurate method for measuring 25(OH)D showed stable mean concentrations in the US population (1988-2006) and recent modest increases (2007-2010). Although it is unclear to what extent supplement usage compared with different laboratory methods explain the increases in 25(OH)D, the use of higher vitamin D supplement dosages coincided with the increase. Marked race-ethnic differences in 25(OH)D concentrations were apparent. These data provide the first standardized information about temporal trends in the vitamin D status of the US population. |
National estimates of serum total 25-hydroxyvitamin D and metabolite concentrations measured by liquid chromatography-tandem mass spectrometry in the US opulation during 2007-2010
Schleicher RL , Sternberg MR , Looker AC , Yetley EA , Lacher DA , Sempos CT , Taylor CL , Durazo-Arvizu RA , Maw KL , Chaudhary-Webb M , Johnson CL , Pfeiffer CM . J Nutr 2016 146 (5) 1051-61 BACKGROUND: The 2007-2010 NHANES provides the first US nationally representative serum 25-hydroxyvitamin D [25(OH)D] concentrations measured by standardized liquid chromatography-tandem mass spectrometry. OBJECTIVE: We describe patterns for total 25(OH)D and individual metabolites in persons aged ≥1 y stratified by race-ethnicity and grouped by demographic, intake, physiologic, and lifestyle variables. METHODS: We measured 25-hydroxycholecalciferol [25(OH)D3], 25-hydroxyergocalciferol [25(OH)D2], and C3-epimer of 25(OH)D3[C3-epi-25(OH)D3] in serum samples (n= 15,652) from the 2007-2010 cross-sectional NHANES [total 25(OH)D = 25(OH)D3+ 25(OH)D2]. RESULTS: Concentrations (median, detection rate) of 25(OH)D3(63.6 nmol/L, 100%) and C3-epi-25(OH)D3(3.40 nmol/L, 86%) were generally detectable; 25(OH)D2was detectable in 19% of the population. Total 25(OH)D, 25(OH)D3, and C3-epi-25(OH)D3displayed similar demographic patterns and were strongly correlated (Spearman'sr> 0.70). Concentrations of 25(OH)D2(90th percentile) were much higher in persons aged ≥60 y (17.3 nmol/L) than in younger age groups (≤4.88 nmol/L). We noted significant race-ethnicity differences in mean total 25(OH)D [non-Hispanic blacks (NHBs), Hispanics, and non-Hispanic whites (NHWs): 46.6, 57.2, and 75.2 nmol/L, respectively] and in the prevalence of total 25(OH)D <30 nmol/L overall (24% of NHBs, 6.4% of Hispanics, and 2.3% of NHWs) as well as stratified by season (winter months: 30% of NHBs, 7.5% of Hispanics, and 3.8% of NHWs; summer months: 17% of NHBs, 4.4% of Hispanics, and 1.6% of NHWs). Persons with higher vitamin D intakes (diet, supplements, or both) and those examined during May-October had significantly higher total 25(OH)D. Significant race-ethnicity interactions in a multiple linear regression model confirmed the necessity of providing race-ethnicity-specific estimates of total 25(OH)D. CONCLUSIONS: Race-ethnicity differences in the prevalence of low total 25(OH)D remained strong even after adjustment for season to account for the NHANES design imbalance between season, latitude, and race-ethnicity. The strong correlation between C3-epi-25(OH)D3and 25(OH)D3may be because the epimer is a metabolite of 25(OH)D3.The presence of 25(OH)D2mainly in older persons is likely a result of high-dose prescription vitamin D2. |
Trabecular bone scores and lumbar spine bone mineral density of US adults: comparison of relationships with demographic and body size variables
Looker AC , Sarafrazi Isfahani N , Fan B , Shepherd JA . Osteoporos Int 2016 27 (8) 2467-75 This study examines demographic patterns and body size relationships in trabecular bone score and lumbar spine BMD of US adults from NHANES 2005-2008. INTRODUCTION: Limited data exist on demographic and body size relationships for trabecular bone score (TBS), a new variable derived from bone texture analysis of lumbar spine dual-energy X-ray absorptiometry (DXA) scans. This study compares demographic patterns and correlations with body size (body mass index (BMI), weight, waist circumference, total body fat, trunk fat, trunk lean) between TBS and lumbar spine bone mineral density (LSBMD) for adults age ≥20 years from the National Health and Nutrition Examination Survey (NHANES) 2005-2008 with BMI in the optimal range for TBS (15-37 kg/m2). METHODS: LSBMD, TBS, body fat, and lean were obtained by DXA. Weight, height, and waist circumference were measured. BMI was calculated from height and weight. RESULTS: Sex differences in TBS varied by age and race/ethnicity (p sex X age interaction and p sex X race/ethnicity interaction < 0.001). In most of the nine demographic subgroups examined, TBS did not differ by sex (four subgroups) or was significantly higher in women (three subgroups). TBS differences by race/ethnicity were inconsistent in men; in women, non-Hispanic whites (NHWs) had higher TBS than non-Hispanic blacks (NHBs) or Mexican Americans (MAs) in all age groups. In contrast, LSBMD was either significantly higher in men (five subgroups) or did not differ by sex (four subgroups). Race/ethnic differences in LSBMD were consistent across age and sex (NHB > NHW > MA). All body size variables were negatively related to TBS but positively related to LSBMD. CONCLUSIONS: Demographic patterns and body size relationships differed between TBS and LSBMD. |
Calcium plus vitamin D supplementation and risk of fractures: an updated meta-analysis from the National Osteoporosis Foundation
Weaver CM , Alexander DD , Boushey CJ , Dawson-Hughes B , Lappe JM , LeBoff MS , Liu S , Looker AC , Wallace TC , Wang DD . Osteoporos Int 2015 27 (1) 367-76 The aim was to meta-analyze randomized controlled trials of calcium plus vitamin D supplementation and fracture prevention. Meta-analysis showed a significant 15 % reduced risk of total fractures (summary relative risk estimate [SRRE], 0.85; 95 % confidence interval [CI], 0.73-0.98) and a 30 % reduced risk of hip fractures (SRRE, 0.70; 95 % CI, 0.56-0.87). INTRODUCTION: Calcium plus vitamin D supplementation has been widely recommended to prevent osteoporosis and subsequent fractures; however, considerable controversy exists regarding the association of such supplementation and fracture risk. The aim was to conduct a meta-analysis of randomized controlled trials [RCTs] of calcium plus vitamin D supplementation and fracture prevention in adults. METHODS: A PubMed literature search was conducted for the period from July 1, 2011 through July 31, 2015. RCTs reporting the effect of calcium plus vitamin D supplementation on fracture incidence were selected from English-language studies. Qualitative and quantitative information was extracted; random-effects meta-analyses were conducted to generate summary relative risk estimates (SRREs) for total and hip fractures. Statistical heterogeneity was assessed using Cochran's Q test and the I 2 statistic, and potential for publication bias was assessed. RESULTS: Of the citations retrieved, eight studies including 30,970 participants met criteria for inclusion in the primary analysis, reporting 195 hip fractures and 2231 total fractures. Meta-analysis of all studies showed that calcium plus vitamin D supplementation produced a statistically significant 15 % reduced risk of total fractures (SRRE, 0.85; 95 % confidence interval [CI], 0.73-0.98) and a 30 % reduced risk of hip fractures (SRRE, 0.70; 95 % CI, 0.56-0.87). Numerous sensitivity and subgroup analyses produced similar summary associations. A limitation is that this study utilized data from subgroup analysis of the Women's Health Initiative. CONCLUSIONS: This meta-analysis of RCTs supports the use of calcium plus vitamin D supplements as an intervention for fracture risk reduction in both community-dwelling and institutionalized middle-aged to older adults. |
B-vitamin status and bone mineral density and risk of lumbar osteoporosis in older females in the United States
Bailey RL , Looker AC , Lu Z , Fan R , Eicher-Miller HA , Fakhouri TH , Gahche JJ , Weaver CM , Mills JL . Am J Clin Nutr 2015 102 (3) 687-94 BACKGROUND: Previous data suggest that elevated serum total homocysteine (tHcy) may be a risk factor for bone fracture and osteoporosis. Nutritional causes of elevated tHcy are suboptimal B-vitamin status. To our knowledge, this is the first nationally representative report on the relation of B vitamins and bone health from a population with folic acid fortification. OBJECTIVE: The purpose of this analysis was to examine the relation between B-vitamin status biomarkers and bone mineral density (BMD), risk of osteoporosis, and biomarkers of bone turnover. DESIGN: We examined the relation of tHcy, methylmalonic acid (MMA), and serum/red blood cell folate and total-body and lumbar spine BMD in women aged ≥50 y participating in the NHANES 1999-2004 (n = 2806), a nationally representative cross-sectional survey. These are the only years with concurrent measurement of tHcy and whole-body dual-energy X-ray absorptiometry. We also examined B-vitamin biomarkers relative to bone turnover markers, bone alkaline phosphatase, and urinary N-terminal cross-linked telopeptide of type I collagen in a 1999-2002 subset with available data (n = 1813). RESULTS: In comparison with optimal concentrations, women with elevated tHcy were older with lower serum vitamin B-12, red blood cell folate, and dietary micronutrient intakes and had significantly higher mean +/- SE markers of bone turnover (bone alkaline phosphatase: 15.8 +/- 0.59 vs. 14.0 +/- 0.25 mug/L; urinary N-terminal cross-linked telopeptide of type I collagen: 48.2 +/- 2.9 vs. 38.9 +/- 0.90 nmol bone collagen equivalents per mmol/L creatinine). Elevated MMA (OR: 1.88; 95% CI: 1.10, 3.18) and tHcy (OR: 2.17; 95% CI: 1.14, 4.15) were related to increased risk of lumbar osteoporosis. When examined as a continuous variable, tHcy was negatively associated, serum folates were positively associated, and MMA and vitamin B-12 were not significantly associated with lumbar and total-body BMD. CONCLUSION: In this nationally representative population of older US women with high exposure to B vitamins through food fortification and dietary supplements, only elevated tHcy and MMA were independently associated with risk of lumbar spine osteoporosis. |
Diabetes and fracture risk in older U.S. adults
Looker AC , Eberhardt MS , Saydah SH . Bone 2015 82 9-15 OBJECTIVE: We examined the diabetes-fracture relationship by race/ethnicity, including the link between pre-diabetes and fracture. RESEARCH DESIGN AND METHODS: We used Medicare- and mortality-linked data for respondents aged 65years and older from the third National Health and Nutrition Examination Survey (NHANES III) and NHANES 1999-2004 for three race/ethnic groups: non-Hispanic whites (NHW), non-Hispanic blacks (NHB), and Mexican Americans (MA). Diabetes was defined as diagnosed diabetes (self-reported) and diabetes status: diagnosed and undiagnosed diabetes (positive diagnosis or hemoglobin A1c (A1C)≥6.5%); pre-diabetes (no diagnosis and A1C between 5.7% and 6.4%); and no diabetes (no diagnosis and A1C<5.7%). Non-skull fractures (n=750) were defined using published algorithms. Hazards ratios (HRs) were calculated using Cox proportional hazards models. RESULTS: The diabetes-fracture relationship differed significantly by race/ethnicity (pinteraction<0.05). Compared to those without diagnosed diabetes, the HRs for those with diagnosed diabetes were 2.37 (95% CI 1.49-3.75), 1.87 (95% CI 1.02-3.40), and 1.22 (95% CI 0.93-1.61) for MA, NHB, and NHW, respectively, after adjusting for significant confounders. HRs for diagnosed and undiagnosed diabetes were similar to those for diagnosed diabetes alone. Pre-diabetes was not significantly related to fracture risk, however. Compared to those without diabetes, adjusted HRs for those with pre-diabetes were 1.42 (95% CI 0.72-2.81), and 1.20 (95% CI 0.96-1.51) for MA and NHW, respectively. There were insufficient fracture cases to examine detailed diabetes status in NHB. CONCLUSIONS: The diabetes-fracture relationship was stronger in MA and NHB. Pre-diabetes was not significantly associated with higher fracture risk, however. |
Dysmobility syndrome and mortality risk in US men and women age 50 years and older
Looker AC . Osteoporos Int 2014 26 (1) 93-102 Mortality risk was significantly elevated in older adults from NHANES 1999-2002 with dysmobility syndrome. INTRODUCTION: Dysmobility syndrome was recently proposed as an approach to evaluate the musculoskeletal health of older persons, but data linking this syndrome to adverse outcomes are currently lacking. The present study used data from the National Health and Nutrition Examination Survey (NHANES) 1999-2002 to assess the relationship between dysmobility and mortality in adults age 50 years and older by age, sex, and race or ethnicity. METHODS: Dysmobility was defined as three or more of the following: high body fat, osteoporosis, low muscle mass, low muscle strength, slow gait speed, or falling risk. Body composition and bone density were assessed with dual energy X-ray absorptiometry. Gait speed was measured via a timed walk, muscle strength via isokinetic knee extension, and fall risk via self-reported balance problems in the past year. Hazard ratios (HRs) for mortality were calculated with Cox proportional hazard models. RESULTS: Twenty-two percent of adults age 50+ years had dysmobility in 1999-2002. Mortality risk by dysmobility varied significantly by age (p interaction = 0.001). HRs for those aged 50-69 years were 3.63 (95 % confidence interval (CI) 2.69, 4.90) and 2.59 (95 % CI 1.82, 3.69), respectively, before and after adjusting for all confounders, compared with 1.46 (95 % CI 1.07, 1.99) and 1.23 (95 % CI 0.89, 1.69) for those aged 70+ years. The relationship was significant when examined by sex or race/ethnicity within age group for most subgroups. CONCLUSIONS: Dysmobility was associated with increased mortality risk in adults age 50 years and older, with risk being higher in those age 50-69 years than in those age 70+ years. |
Hemoglobin and hip fracture risk in older non-Hispanic white adults
Looker AC . Osteoporos Int 2014 25 (10) 2389-98 The relationship between hemoglobin and hip fracture was examined in older non-Hispanic white adults from the third National Health and Nutrition Examination Survey (NHANES III). Both low and high hemoglobin values were associated with increased hip fracture risk before and after adjusting for selected risk factors. INTRODUCTION: The few studies to date that have examined the relationship between hemoglobin and fracture risk have focused on low hemoglobin values. The present study examined hip fracture risk across the hemoglobin distribution in older non-Hispanic white adults from the third National Health and Nutrition Examination Survey (NHANES III, 1988-1994). METHODS: Hemoglobin was measured using a Coulter S-plus Jr.(R) (Coulter Electronics, Hialeah, FL) in 2,122 non-Hispanic whites age 65 years and older. Hip fracture cases were identified using linked Medicare and mortality records obtained through 2007. Cox proportional hazards models were used to assess the best-fitting model and to estimate the hazards ratio (HR) for hip fracture by hemoglobin decile before and after adjusting for selected confounders. RESULTS: There were 239 hip fracture cases in the analytic sample. The best fitting model was quadratic. When compared to values in the middle of the distribution, those with hemoglobin in the lowest and highest deciles had increased hip fracture risk (HRlowest decile = 2.96, 95 % confidence interval (CI) 1.44-6.08; HRhighest decile = 2.06, 95 % CI 1.09-3.92) after adjusting for age and sex. Both HRs remained significant after adjusting for additional confounders (HRlowest decile = 2.24, 95 % CI 1.09-3.92; HRhighest decile = 2.37, 95 % CI 1.35-4.16). CONCLUSIONS: Both low and high hemoglobin values were associated with increased hip fracture risk. The mechanism underlying the relationship is not clear, but there were some suggestions that it may differ for low versus high hemoglobin. |
Relationship between femur neck bone mineral density and prevalent chronic obstructive pulmonary disease (COPD) or COPD mortality in older non-Hispanic white adults from NHANES III
Looker AC . Osteoporos Int 2014 25 (3) 1043-52 The relationship between femur neck bone mineral density (FNBMD), prevalent COPD, and COPD mortality was examined in older non-Hispanic white adults from NHANES III. FNBMD was significantly related to prevalent COPD and COPD mortality before and after adjusting for shared risk factors. INTRODUCTION: Bone mineral density (BMD) has been linked to chronic obstructive pulmonary disease (COPD), but little is known about its relationship with COPD mortality. The present study examined the relationship between FNBMD, prevalent COPD, and COPD mortality in older non-Hispanic white adults from the third National Health and Nutrition Examination Survey (NHANES III, 1988-1994). METHODS: COPD status at baseline was defined by self-reported physician's diagnosis and by airway obstruction based on spirometry measurements in 3,275 non-Hispanic whites aged 50 years and older. COPD mortality cases were identified using linked mortality records obtained through 2006. FNBMD was measured by dual-energy x-ray absorptiometry. Multiple regression was used to examine the baseline relationship between COPD and FNBMD. Cox proportional hazards models were used to estimate the hazards ratio (HR) for COPD mortality by FNBMD. RESULTS: Twelve percent self-reported a physician's diagnosis of COPD, 23 % had mild or moderate airway obstruction, and 9 % had severe or very severe airway obstruction. There were 180 COPD mortality cases in the sample. FNBMD was significantly lower in those with self-reported COPD diagnosis or airway obstruction before and after adjusting for shared risk factors (p < 0.05). COPD mortality risk was significantly increased for each standard deviation decline in FNBMD before (by 68 %) and after (by 26-38 %) adjusting for shared risk factors. CONCLUSIONS: Low FNBMD was associated with both baseline COPD and future COPD mortality. Shared risk factors appeared to explain some, but not all, of these relationships. |
Is there a reverse J-shaped association between 25-hydroxyvitamin D and all-cause mortality? Results from the U.S. Nationally Representative NHANES
Sempos CT , Durazo-Arvizu RA , Dawson-Hughes B , Yetley EA , Looker AC , Schleicher RL , Cao G , Burt V , Kramer H , Bailey RL , Dwyer JT , Zhang X , Gahche J , Coates PM , Picciano MF . J Clin Endocrinol Metab 2013 98 (7) 3001-9 CONTEXT: A reverse J-shaped association between serum 25-hydroxyvitamin D (25[OH]D) concentration and all-cause mortality was suggested in a 9-year follow-up (1991-2000) analysis of the Third National Health and Nutrition Examination Survey (NHANES III, 1988-1994). OBJECTIVE: Our objective was to repeat the analyses with 6 years additional follow-up to evaluate whether the association persists through 15 years of follow-up. PARTICIPANTS: The study included 15 099 participants aged ≥20 years with 3784 deaths. MAIN OUTCOME MEASURE: Relative risk (RR) of death from all causes was adjusted for age, sex, race/ethnicity, and season using 2 Poisson regression approaches: traditional categorical and cubic splines. Results were given for 9 25(OH)D levels: <20, 20 to 29, 30 to 39, 40 to 49, 50 to 59, 60 to 74, 75 to 99 (reference), 100 to 119, and ≥120 nmol/L. RESULTS: The reverse J-shaped association became stronger with longer follow-up and was not affected by excluding deaths within the first 3 years of follow-up. Similar results were found from both statistical approaches for levels <20 through 119 nmol/L. Adjusted RR (95% confidence interval [CI]) estimates for all levels <60 nmol/L were significantly >1 compared with the reference group. The nadir of risk was 81 nmol/L (95% CI, 73-90 nmol/L). For 25(OH)D ≥120 nmol/L, results (RR, 95% CI) were slightly different using traditional categorical (1.5, 1.02-2.3) and cubic splines approaches (1.2, 0.9-1.4). The association appeared in men, women, adults ages 20 to 64 years, and non-Hispanic whites but was weaker in older adults. The study was too small to evaluate the association in non-Hispanic black and Mexican-American adults. CONCLUSIONS: A reverse J-shaped association between serum 25(OH)D and all-cause mortality appears to be real. It is uncertain whether the association is causal. |
Femur neck bone mineral density and fracture risk by age, sex, and race or Hispanic origin in older US adults from NHANES III
Looker AC . Arch Osteoporos 2013 8 141 Differences in the relationship between femur neck bone mineral density (FNBMD) and fracture risk were examined by age, sex, and race/ethnicity in the third National Health and Nutrition Examination Survey (NHANES III) cohort. FNBMD had similar, significant predictive utility for fracture in the different subgroups, but it did not completely account for subgroup differences in risk. PURPOSE: Few previous studies of FNBMD and fracture risk examined the relationship by age, sex, and race within the same cohort. The present study examined the relationship between FNBMD and risk of incident major osteoporotic fracture (hip, spine, radius, and humerus) in older US adults from NHANES III (1988-1994). METHODS: Incident fractures were identified using linked mortality and Medicare records obtained through 2007 for 2,743 men and women ages 65 years and older. FNBMD was measured by dual-energy X-ray absorptiometry. Cox proportional hazards models were used to estimate the hazards ratio (HR) of fracture for FNBMD and femur neck T score and risk of major osteoporotic fracture. RESULTS: The sample included 380 incident major osteoporotic fractures. Fracture risk approximately doubled for each SD decrease in FNBMD. HR's for FNBMD were similar within age, sex, or race/Hispanic origin subgroups, and also for T scores calculated with either white female or sex- and race/ethnic-specific reference data. Adding FNBMD to Cox models slightly attenuated HR for age, sex, or race/Hispanic origin, but all three variables remained significant predictors of fracture risk. CONCLUSIONS: FNBMD had similar, significant predictive utility within age, sex, and race/Hispanic origin subgroups. However, FNBMD did not appear to completely account for fracture risk differences in these subgroups. Similarity of HR's for T scores calculated with two different reference databases support use of a uniform reference database to calculate these scores. |
Serum 25-hydroxyvitamin D and risk of major osteoporotic fractures in older U.S. adults
Looker AC . J Bone Miner Res 2012 28 (5) 997-1006 Results from previous prospective studies linking serum hydroxyvitamin D (25OHD) with fracture risk have been inconsistent. The present study examined the relationship between serum 25OHD and risk of incident major osteoporotic fracture (hip, spine, radius and humerus) in older US adults. The study used a pooled cohort of 4749 men and women ages 65 years and older from the third National Health and Nutrition Examination Survey (NHANES III, 1988-94) and NHANES 2000-2004. Incident fractures were identified using linked mortality and Medicare records that were obtained for participants from both surveys. Serum 25OHD values were measured by radioimmunoassay in both surveys. Cox proportional hazards models were used to estimate the relative risk (RR) of fracture by serum 25OHD level. There were 525 incident major osteoporotic fractures (287 hip fractures) in the sample. Serum 25OHD was a significant linear predictor of major osteoporotic fracture and significant quadratic predictor of hip fracture in the total sample and among those with less than 10 years of follow-up, but it was not related to risk of either fracture type among those with > 10 years of follow-up. Major osteoporotic fracture risk was increased by 26-27% for each SD decrease in serum 25OHD among those with less than 10 years of follow-up. Serum 25OHD was significantly related to risk of major osteoporotic fractures as a group and to hip fracture alone in this cohort of older US adults from NHANES III and NHANES 2000-2004. However, the predictive utility of serum 25OHD diminished after ten years. In addition, the relationship appeared to be linear when major osteoporotic fracture risk was considered but quadratic when hip fracture risk was assessed. (c) 2012 American Society for Bone and Mineral Research. |
Serum soluble transferrin receptor concentrations in US preschool children and non-pregnant women of childbearing age from the National Health and Nutrition Examination Survey 2003-2010
Mei Z , Pfeiffer CM , Looker AC , Flores-Ayala RC , Lacher DA , Mirel LB , Grummer-Strawn LM . Clin Chim Acta 2012 413 1479-84 BACKGROUND: Serum soluble transferrin receptor (sTfR) is recommended as a sensitive and accurate measure of iron deficiency (ID) in populations when only a single indicator can be used. The lack of assay standardization and of representative data on the distribution of sTfR in at-risk populations currently limits its utility. METHODS: Using data from NHANES 2003-2010, we examined the distribution of sTfR and developed assay-specific cutoff values for defining elevated sTfR in 2 US populations groups: children aged 1-5 y (n=2820) and non-pregnant women aged 15-49 y (n=6575). RESULTS: On average, children had higher geometric mean sTfR concentrations (4.09mg/l; 95% CI: 4.04-4.14) than non-pregnant women (3.31mg/l; 95% CI: 3.26-3.35) (p<0.001). Among children, those aged 1-2 y (compared to those aged 3-5 y), boys (compared to girls), and non-Hispanic black (NHB) children (compared to non-Hispanic white (NHW) and Mexican-American (MA) children) had higher sTfR concentrations. Among non-pregnant women, adolescents (15-19 y) had higher sTfR concentrations than adults aged 20-34 y but not compared to adults aged 35-49 y; NHB women (compared to NHW and MA women) and multiparous women (compared to nulliparous women) had higher sTfR concentrations. The derived cutoff values (97.5th percentile in a defined healthy reference population) for defining elevated sTfR in the US were 6.00mg/l for children 1-5 y and 5.33mg/l for non-pregnant women 15-49 y. CONCLUSIONS: A different sTfR cutoff value may be needed in children and non-pregnant women to define ID. |
The potential impact of the National Osteoporosis Foundation guidance on treatment eligibility in the USA: an update in NHANES 2005-2008
Dawson-Hughes B , Looker AC , Tosteson AN , Johansson H , Kanis JA , Melton LJ 3rd . Osteoporos Int 2012 23 (3) 811-20 This analysis of National Health and Nutrition Examination Survey (NHANES) 2005-2008 data describes the prevalence of risk factors for osteoporosis and the proportions of men and postmenopausal women age 50 years and older who are candidates for treatment to lower fracture risk, according to the new Fracture Risk Assessment Tool (FRAX)-based National Osteoporosis Foundation Clinician's Guide. INTRODUCTION: It is important to update estimates of the proportions of the older US population considered eligible for pharmacologic treatment for osteoporosis for purposes of understanding the health care burden of this disease. METHODS: This is a cross-sectional study of the NHANES 2005-2008 data in 3,608 men and women aged 50 years and older. Variables in the analysis included race/ethnicity, age, lumbar spine and femoral neck bone mineral density, risk factor profiles, and FRAX 10-year fracture probabilities. RESULTS: The prevalence of osteoporosis of the femoral neck ranged from 6.0% in non-Hispanic black to 12.6% in Mexican American women. Spinal osteoporosis was more prevalent among Mexican American women (24.4%) than among either non-Hispanic blacks (5.3%) or non-Hispanic whites (10.9%). Treatment eligibility was similar in Mexican American and non-Hispanic white women (32.0% and 32.8%) and higher than it was in non-Hispanic black women (11.0%). Treatment eligibility among men was 21.1% in non-Hispanic whites, 12.6% in Mexican Americans, and 3.0% in non-Hispanic blacks. CONCLUSIONS: Nineteen percent of older men and 30% of older women in the USA are at sufficient risk for fracture to warrant consideration for pharmacotherapy. |
Changes in femur neck bone density in US adults between 1988-1994 and 2005-2008: demographic patterns and possible determinants
Looker AC , Melton LJ 3rd , Borrud LG , Shepherd JA . Osteoporos Int 2012 23 (2) 771-80 SUMMARY: This analysis compares femur neck bone mineral density (FNBMD) and bone determinants in adults between National Health and Nutrition Examination Survey (NHANES) III (1988-1994) and NHANES 2005-2008. FNBMD was higher in NHANES 2005-2008 than in NHANES III, but between-survey differences varied by age, sex, and race/ethnicity. The likelihood that FNBMD has improved appears strongest for older white women. INTRODUCTION: Recent data on hip fracture incidence and femur neck osteoporosis suggest that the skeletal status of older US adults has improved since the 1990s, but the explanation for these changes remains uncertain. METHODS: The present study compares mean FNBMD of adults ages 20 years and older between the third (NHANES III, 1988-1994) and NHANES 2005-2008. Dual-energy X-ray absorptiometry systems (pencil beam in NHANES III, fan beam in NHANES 2005-2008) were used to measure hip BMD, and several bone determinants are compared between surveys to assess their potential role in explaining observed FNBMD differences. RESULTS: FNBMD was higher overall in NHANES 2005-2008 than in NHANES III, but between-survey differences varied by age, sex, and race/ethnicity. Although FNBMD differences in several groups were small enough (≤3%) to be attributable to use of different dual-energy X-ray absorptiometry (DXA) systems in the two surveys, variability in size and direction of the differences does not support artifactual differences in DXA methodology as the sole explanation. Several FNBMD determinants (body size, smoking, selected bone-active medications, self-reported health status, calcium intake, and caffeine consumption) changed in a bone-improving direction in older adults, but FNBMD in older non-Hispanic white women remained significantly higher in 2005-2008 even after adjusting for DXA methodology or for the selected bone determinants. CONCLUSION: The likelihood that FNBMD has improved appears strongest for older white women, but the reason for the improvement in this group remains unclear. |
Lumbar spine bone mineral density in US adults: demographic patterns and relationship with femur neck skeletal status
Looker AC , Melton LJ 3rd , Borrud LG , Shepherd JA . Osteoporos Int 2011 23 (4) 1351-60 This analysis examines lumbar spine bone mineral density (BMD) of US adults from NHANES 2005-2008 by age, sex, and race/ethnicity. Prevalence of low spine BMD and agreement between the prevalence of low BMD at the spine and femur neck in older adults are also assessed. INTRODUCTION: Lumbar spine BMD data from a representative sample of the US population have not been previously available. METHODS: We used data from the National Health and Nutrition Examination Survey 2005-2008 to examine demographic patterns in lumbar spine BMD among US adults age ≥20 years and the prevalence of low lumbar spine BMD in adults age ≥50 years. Agreement between the prevalence of low BMD at the femur neck and spine in older adults was also assessed. Dual-energy X-ray absorptiometry was used to measure lumbar spine and femur neck BMD. World Health Organization definitions were used to categorize skeletal status as normal, osteopenia, or osteoporosis. RESULTS: Compared to non-Hispanic whites, non-Hispanic blacks had higher and Mexican Americans had lower lumbar spine BMD. Lumbar spine BMD declined with age in women, but not in men. Approximately 4.7 million (10%) older US women and 1 million (3%) older men had lumbar spine osteoporosis in 2005-2008. Roughly one third of them differed in skeletal status at the spine and hip but most were normal at one site and osteopenic at the other. Only 3-10%, depending on sex, had osteoporosis at one skeletal site but not at the other skeletal site. Between 76% and 87% with discordant skeletal status had lumbar spine T-scores within 1 unit of the category threshold. CONCLUSIONS: These findings suggest that measuring either the femur neck or the lumbar spine will correctly classify the majority of individuals who present for care as osteoporotic or not. |
Assessment of iron status in US pregnant women from the National Health and Nutrition Examination Survey (NHANES), 1999-2006
Mei Z , Cogswell ME , Looker AC , Pfeiffer CM , Cusick SE , Lacher DA , Grummer-Strawn LM . Am J Clin Nutr 2011 93 (6) 1312-20 BACKGROUND: Total body iron calculated from serum ferritin and soluble transferrin receptor concentrations allows for the evaluation of the full range of iron status. OBJECTIVE: We described the distribution of total body iron and the prevalence of iron deficiency (ID) on the basis of total body iron in US pregnant women. DESIGN: We examined data from the National Health and Nutrition Examination Survey (NHANES) in 1999-2006 for 1171 pregnant women. RESULTS: ID prevalence (+/-SE) in US pregnant women, which was defined as total body iron <0 mg/kg, was 18.0 +/- 1.4%. Pregnant women in the first trimester had a higher mean total body iron than did pregnant women in the second or third trimesters. ID prevalence in pregnant women increased significantly with each trimester (6.9 +/- 2.2%, 14.3 +/- 2.1%, and 29.5 +/- 2.7% in the first, second, and third trimesters, respectively). Pregnant women with parity ≥2 had the lowest mean total body iron and the highest prevalence of ID compared with values for pregnant women with parity of 0 or 1. The ID prevalence in non-Hispanic white pregnant women was significantly lower than in Mexican American or non-Hispanic black pregnant women. The mean total body iron and the prevalence of ID did not differ by educational level or by family income. CONCLUSIONS: To our knowledge, these are the first data on total body iron distributions for a representative sample of US pregnant women. Low total body iron is more prevalent in pregnant women in the second or third trimesters, in Mexican American pregnant women, in non-Hispanic black pregnant women, and in women with parity ≥2. |
Serum 25-hydroxyvitamin D and cancer mortality in the NHANES III study (1988-2006)
Freedman DM , Looker AC , Abnet CC , Linet MS , Graubard BI . Cancer Res 2010 70 (21) 8587-97 Vitamin D has been hypothesized to protect against cancer. We followed 16,819 participants in NHANES III (Third National Health and Nutritional Examination Survey) from 1988 to 2006, expanding on an earlier NHANES III study (1988-2000). Using Cox proportional hazards regression models, we examined risk related to baseline serum 25-hydroxyvitamin D [25(OH)D] for total cancer mortality, in both sexes, and by racial/ethnic groups, as well as for site-specific cancers. Because serum was collected in the south in cooler months and in the north in warmer months, we examined associations by collection season ("summer/higher latitude" and "winter/lower latitude"). We identified 884 cancer deaths during 225,212 person-years. Overall cancer mortality risks were unrelated to baseline 25(OH)D status in both season/latitude groups, and in non-Hispanic whites, non-Hispanic blacks, and Mexican-Americans. In men, risks were elevated at higher levels {e.g., for ≥100 nmol/L, relative risk (RR) = 1.85 [95% confidence interval (CI), 1.02-3.35] compared with <37.5 nmol/L}. Although risks were unrelated to 25(OH)D in all women combined, risks significantly decreased with increasing 25(OH)D in the summer/higher latitude group [for ≥100 nmol/L, RR = 0.52 (95% CI, 0.25-1.15) compared with <37.5 nmol/L; P(trend) = 0.03, based on continuous values]. We also observed a suggestion of an inverse association with colorectal cancer mortality (P(trend) = 0.09) and a positive association with lung cancer mortality among males (P(trend) = 0.03). Our results do not support the hypothesis that 25(OH)D is associated with reduced cancer mortality. Although cancer mortality in females was inversely associated with 25(OH)D in the summer/higher latitude group, cancer mortality at some sites was increased among men with higher 25(OH)D. These findings argue for caution before increasing 25(OH)D levels to prevent cancer. |
Multiple imputation of missing dual-energy X-ray absorptiometry data in the National Health and Nutrition Examination Survey
Schenker N , Borrud LG , Burt VL , Curtin LR , Flegal KM , Hughes J , Johnson CL , Looker AC , Mirel L . Stat Med 2010 30 (3) 260-76 In 1999, dual-energy x-ray absorptiometry (DXA) scans were added to the National Health and Nutrition Examination Survey (NHANES) to provide information on soft tissue composition and bone mineral content. However, in 1999-2004, DXA data were missing in whole or in part for about 21 per cent of the NHANES participants eligible for the DXA examination; and the missingness is associated with important characteristics such as body mass index and age. To handle this missing-data problem, multiple imputation of the missing DXA data was performed. Several features made the project interesting and challenging statistically, including the relationship between missingness on the DXA measures and the values of other variables; the highly multivariate nature of the variables being imputed; the need to transform the DXA variables during the imputation process; the desire to use a large number of non-DXA predictors, many of which had small amounts of missing data themselves, in the imputation models; the use of lower bounds in the imputation procedure; and relationships between the DXA variables and other variables, which helped both in creating and evaluating the imputations. This paper describes the imputation models, methods, and evaluations for this publicly available data resource and demonstrates properties of the imputations via examples of analyses of the data. The analyses suggest that imputation helps to correct biases that occur in estimates based on the data without imputation, and that it helps to increase the precision of estimates as well. Moreover, multiple imputation usually yields larger estimated standard errors than those obtained with single imputation. Published in 2010 by John Wiley & Sons, Ltd. |
NHANES monitoring of serum 25-hydroxyvitamin D: a roundtable summary
Yetley EA , Pfeiffer CM , Schleicher RL , Phinney KW , Lacher DA , Christakos S , Eckfeldt JH , Fleet JC , Howard G , Hoofnagle AN , Hui SL , Lensmeyer GL , Massaro J , Peacock M , Rosner B , Wiebe D , Bailey RL , Coates PM , Looker AC , Sempos C , Johnson CL , Picciano MF . J Nutr 2010 140 (11) 2030S-45S A roundtable to discuss monitoring of serum 25-hydroxyvitamin D [25(OH)D] in the NHANES was held in late July 2009. Topics included the following: 1) options for dealing with assay fluctuations in serum 25(OH)D in the NHANES conducted between 1988 and 2006; 2) approaches for transitioning between the RIA used in the NHANES between 1988 and 2006 to the liquid chromatography tandem MS (LC-MS/MS) measurement procedure to be used in NHANES 2007 and later; 3) approaches for integrating the recently available standard reference material for vitamin D in human serum (SRM 972) from the National Institute of Standards and Technology (NIST) into the NHANES; 4) questions regarding whether the C-3 epimer of 25-hydroxyvitamin D3 [3-epi-25(OH)D3] should be measured in NHANES 2007 and later; and 5) identification of research and educational needs. The roundtable experts agreed that the NHANES data needed to be adjusted to control for assay fluctuations and offered several options for addressing this issue. The experts suggested that the LC-MS/MS measurement procedure developed by NIST could serve as a higher order reference measurement procedure. They noted the need for a commutability study for the recently released NIST SRM 972 across a range of measurement procedures. They suggested that federal agencies and professional organizations work with manufacturers to improve the quality and comparability of measurement procedures across all laboratories. The experts noted the preliminary nature of the evidence of the 3-epi-25(OH)D3 but felt that it should be measured in 2007 NHANES and later. |
Age, gender, and race/ethnic differences in total body and subregional bone density
Looker AC , Melton LJ 3rd , Harris T , Borrud L , Shepherd J , McGowan J . Osteoporos Int 2009 20 (7) 1141-9 SUMMARY: Total body bone density of adults from National Health and Nutrition Examination Survey (NHANES) 1999-2004 differed as expected for some groups (men>women and blacks>whites) but not others (whites>Mexican Americans). Cross-sectional age patterns in bone mineral density (BMD) of older adults differed at skeletal sites that varied by degree of weight-bearing. INTRODUCTION: Total body dual-energy X-ray absorptiometry (DXA) data offer the opportunity to compare bone density of demographic groups across the entire skeleton. METHODS: The present study uses total body DXA data (Hologic QDR 4500A, Hologic, Bedford MA, USA) from the NHANES 1999-2004 to examine BMD of the total body and selected skeletal subregions in a wide age range of adult men and women from three race/ethnic groups. Total body, lumbar spine, pelvis, right leg, and left arm BMD and lean mass from 13,091 adults aged 20 years and older were used. The subregions were chosen to represent sites with different degrees of weight-bearing. RESULTS: Mean BMD varied in expected ways for some demographic characteristics (men>women and non-Hispanic blacks>non-Hispanic whites) but not others (non-Hispanic whites>Mexican Americans). Differences in age patterns in BMD also emerged for some characteristics (sex) but not others (race/ethnicity). Differences in cross-sectional age patterns in BMD and lean mass by degree of weight-bearing in older adults were observed for the pelvis, leg, and arm. CONCLUSION: This information may be useful for generating hypotheses about age, race, and sex differences in fracture risk in the population. |
Hip fracture risk in older US adults by treatment eligibility status based on new National Osteoporosis Foundation guidance
Looker AC , Dawson-Hughes B , Tosteson AN , Johansson H , Kanis JA , Melton 3rd LJ . Osteoporos Int 2010 22 (2) 541-9 This analysis of National Health and Nutrition Examination Survey III data found a significant risk of incident hip fracture in adults aged 65 years and older who are candidates for treatment to lower fracture risk, according to the new National Osteoporosis Foundation Clinician's Guide. INTRODUCTION: The relationship between treatment eligibility by the new National Osteoporosis Foundation (NOF) Guide to the Prevention and Treatment of Osteoporosis and the risk of subsequent hip fracture is unknown. METHODS: The study sample consisted of 3,208 men and women ages 65 years and older who were examined in the third National Health and Nutrition Examination Survey (NHANES III, 1988-1994), a nationally representative survey. Risk factors used to define treatment eligibility at baseline were measured in NHANES III or were simulated using World Health Organization study cohorts. Incident hip fractures were ascertained using linked mortality and Medicare records that were obtained for NHANES III participants through December 31, 2000. Cox proportional hazards models were used to estimate the relative risk (RR) of hip fracture by treatment eligibility status. RESULTS: The RR for subsequent hip fracture was 4.9 (95% CI 3.30, 7.94) in treatment-eligible vs treatment-ineligible persons. The increased risk for treatment-eligible persons remained statistically significant when examined by sex or age: RR(men) = 5.5 (2.6, 11.4) and RR(women) = 4.3 (2.2, 8.4); RR(65-79 y) = 4.8 (2.6, 8.7) and RR(80+ y) = 4.6 (2.1, 10.1). CONCLUSIONS: Treatment-eligible persons were about five times more likely to experience a subsequent hip fracture than the non-eligible persons. The new NOF guidelines appear to predict future hip fracture risk equally in men as in women, and fracture risk prediction did not appear to diminish with age. |
Three-phase model harmonizes estimates of the maximal suppression of parathyroid hormone by 25-hydroxyvitamin D in persons 65 years of age and older
Durazo-Arvizu RA , Dawson-Hughes B , Sempos CT , Yetley EA , Looker AC , Cao G , Harris SS , Burt VL , Carriquiry AL , Picciano MF . J Nutr 2010 140 (3) 595-9 The concentration or threshold of 25-hydroxyvitamin D [25(OH)D] needed to maximally suppress intact serum parathyroid hormone (iPTH) has been suggested as a measure of optimal vitamin D status. Depending upon the definition of maximal suppression of iPTH and the 2-phase regression approach used, 2 distinct clusters for a single 25(OH)D threshold have been reported: 16-20 ng/mL (40-50 nmol/L) and 30-32 ng/mL (75-80 nmol/L). To rationalize the apparently disparate published results, we compared thresholds from several regression models including a 3-phase one to estimate simultaneously 2 thresholds before and after adjusting for possible confounding for age, BMI, glomerular filtration rate, dietary calcium, and season (April-September vs. October-March) within a single data set, i.e. data from the Tufts University Sites Testing Osteoporosis Prevention/Intervention Treatment study, consisting of 181 men and 206 women (total n = 387) ages 65-87 y. Plasma 25(OH)D and serum iPTH concentrations were (mean +/- SD) 22.1 +/- 7.44 ng/mL (55.25 +/- 18.6 nmol/L) and 36.6 +/- 16.03 pg/mL (3.88 +/- 1.7 pmol/L), respectively. The 3-phase model identified 2 thresholds of 12 ng/mL (30 nmol/L) and 28 ng/mL (70 nmol/L); similar results were found from the 2-phase models evaluated, i.e. 13-20 and 27-30 ng/mL (32.5-50 and 67.5-75 nmol/L) and with previous results. Adjusting for confounding did not change the results substantially. Accordingly, the 3-phase model appears to be superior to the 2-phase approach, because it simultaneously estimates the 2 threshold clusters found from the 2-phase approaches along with estimating confidence limits. If replicated, it may be of both clinical and public health importance. |
Prevalence and trends in low femur bone density among older US adults: NHANES 2005-2006 compared with NHANES III
Looker AC , Melton LJ III , Harris TB , Borrud LG , Shepherd JA . J Bone Miner Res 2010 25 (1) 64-71 Hip fracture incidence appears to be declining in the United States, but changes in bone mineral density (BMD) of the population have not been evaluated. We used femur BMD data from the National Health and Nutrition Examination Survey (NHANES) 2005-2006 to estimate the prevalence of low femoral BMD in adults age 50 years and older and compared it with estimates from NHANES III (1988-1994). Dual-energy X-ray absorptiometry systems (pencil-beam geometry in NHANES III, fan-beam geometry in NHANES 2005-2006) were used to measure femur BMD, and World Health Organization (WHO) definitions of low BMD were used to categorize skeletal status. In 2005-2006, 49% of older US women had osteopenia and 10% had osteoporosis at the femur neck. In men, 30% had femur neck osteopenia and 2% had femur neck osteoporosis. An estimated 5.3 million older men and women had osteoporosis at the femur neck, and 34.5 million more had osteopenia in 2005-2006. When compared with NHANES III, the age-adjusted prevalence of femur neck osteoporosis in NHANES 2005-2006 was lower in men (by 3 percentage units) and women (by 7 percentage units) overall and among non-Hispanic whites. Changes in body mass index or osteoporosis medication use between surveys did not fully explain the decline in osteoporosis. Owing to the increase in the number of older adults in the US population, however, more older adults had low femur neck BMD (osteoporosis+osteopenia) in 2005-2006 than in 1988-1994. Thus, despite the decline in prevalence, the estimated number of affected older adults in 2005-2006 remained high. |
The potential impact of new National Osteoporosis Foundation guidance on treatment patterns
Dawson-Hughes B , Looker AC , Tosteson AN , Johansson H , Kanis JA , Melton LJ 3rd . Osteoporos Int 2010 21 (1) 41-52 This analysis of National Health and Nutrition Examination Survey III data describes the prevalence of risk factors for osteoporosis and the proportions of men and postmenopausal women age 50 years and older who are candidates for treatment to lower fracture risk, according to the new FRAX-based National Osteoporosis Foundation Clinician's Guide. INTRODUCTION: Little information is available on prevalence of osteoporosis risk factors or proportions of US men and women who are potential candidates for treatment. METHODS: The prevalence of risk factors used in the new National Osteoporosis Foundation (NOF) FRAX-based Guide to the Prevention and Treatment of Osteoporosis was estimated using data from the third National Health and Nutrition Examination Survey (NHANES III). Risk factors not measured in NHANES III were simulated using World Health Organization cohorts. The proportion of US men and postmenopausal women age 50+ years who are treatment candidates by the new NOF Guide were calculated; for non-Hispanic white (NHW) women, the proportion eligible by the new NOF Guide was compared with that based on an earlier NOF Guide. RESULTS: Twenty percent of men and 37% of women were potential candidates for treatment to prevent fractures by the new NOF Guide. Among NHW women, 53% were potential candidates by the previous NOF Guide compared with 41% by the new guide. CONCLUSIONS: One fifth of men and 37% of postmenopausal women are eligible for osteoporosis treatment consideration by the new NOF Guide. However, fewer NHW women are eligible by the new guide than by the previous NOF Guide. |
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