Kamil E. Barbour

Serum 25-hydroxyvitamin D and clinical fracture risk in a multiethnic cohort of women: The women's health initiative (WHI)

Low 25‐hydroxyvitamin D [25(OH)D] levels have been linked to hip fracture in white women. To study the association of 25(OH)D with risk of fracture in multiethnic women, we performed a nested case‐control study within the prospective Womens Health Initiative (WHI) Observational Study. Incident fractures were identified in 381 black, 192 Hispanic, 113 Asian, and 46 Native American women over an average of 8.6 years. A random sample of 400 white women who fractured was chosen. One control individual was selected per case and matched on age, race/ethnicity, and blood draw date. 25(OH)D, parathyroid hormone, and vitamin D–binding protein (DBP) were measured in fasting baseline serum. Conditional logistic regression models were used to calculate the odds ratio (OR) and 95% CI. In multivariable models, higher 25(OH)D levels compared with levels less than 20 ng/mL were associated with a lower risk of fracture in white women (20 to <30 ng/mL: OR = 0.82, 95% CI 0.58–1.16; ≤30.0 ng/mL: OR = 0.56, 95% CI 0.35–0.90; p trend = 0.02). In contrast, higher 25(OH)D (≥20 ng/mL) compared with levels less than 20 ng/mL were associated with a higher risk of fracture in black women (OR = 1.45, 95% CI 1.06–1.98; p trend = 0.043). Higher 25(OH)D (≥30.0 ng/mL) was associated with higher fracture risk in Asian women after adjusting for DBP (OR = 2.78, 95% CI 0.99–7.80; p trend = 0.04). There was no association between 25(OH)D and fracture in Hispanic or Native American women. Our results suggest divergent associations between 25(OH)D and fracture by race/ethnicity. The optimal level of 25(OH)D for skeletal health may differ in white and black women.

Adipokines and the Risk of Fracture in Older Adults

Adiponectin and leptin are adipokines that influence bone metabolism in vitro and in animal models. However, less is known about the longitudinal association of leptin and adiponectin with fracture. We tested the hypothesis that low leptin and high adiponectin levels are each individually associated with fracture risk in a prospective cohort study in Memphis and Pittsburgh among 3075 women and men aged 70 to 79 years from the Health Aging and Body Composition (Health ABC) study. There were 406 incident fractures (334 nonvertebral and 72 vertebral) over a mean of 6.5 ± 1.9 years. Cox regression was used to estimate the hazard ratios for fracture. Sex modified the association between adiponectin and fracture (p = .025 for interaction). Men with the highest adiponectin level (tertile 3) had a 94% higher risk of fracture [hazard ratio (HR) = 1.94; 95% confidence interval (CI) 1.20–3.16] compared with the lowest tertile (tertile 1; p = .007 for trend) after adjusting age, race, body mass index (BMI), education, diabetes, weight change, and hip bone mineral density (BMD). Among women, after adjusting for age and race, this association was no longer significant (p = .369 for trend). Leptin did not predict fracture risk in women (p = .544 for trend) or men (p = .118 for trend) in the multivariate models. Our results suggest that adiponectin, but not leptin, may be a novel risk factor for increased fracture risk independent of body composition and BMD and that these relationships may be influenced by sex. More research is needed to understand the physiologic basis underlying these sex differences.

Inflammatory markers and the risk of hip fracture: the Women's Health Initiative.

Cytokines play a major role in bone remodeling in vitro and in animal models, with evidence supporting the involvement of inflammatory markers in the pathogenesis of osteoporosis. However, less is known about the longitudinal association of inflammatory markers with hip fracture. We tested whether high receptor levels of proinflammatory cytokines are associated with an increased risk of hip fracture in older women. We used a nested case‐control study design from the Womens Health Initiative Observational Study (WHI‐OS) and selected 400 cases with physician‐adjudicated incident hip fractures and 400 controls matched on age, race, and date of blood draw. Participants were chosen from 39,795 postmenopausal women without previous hip fractures, not using estrogens or other bone‐active therapies. Incident hip fractures (median follow‐up 7.1 years) were verified by review of radiographs and confirmed by blinded central adjudicators. Hip fractures with a pathological cause were excluded. In multivariable models, the risk of hip fracture for subjects with the highest levels of inflammatory markers (quartile 4) compared with those with lower levels (quartiles 1, 2, and 3) was 1.43 (95% confidence interval [CI], 0.98–2.07) for interleukin‐6 (IL‐6) soluble receptor (SR), 1.40 (95% CI, 0.97–2.03) for tumor necrosis factor (TNF) SR1, and 1.56 (95% CI, 1.09–2.22) for TNF SR2. In subjects with all three markers in the highest quartile, the risk ratio of fracture was 2.76 (95% CI, 1.22–6.25) in comparison with subjects with 0 or 1 elevated marker(s) (p trend = 0.018). Elevated levels of inflammatory markers for all three cytokine‐soluble receptors were associated with an increased risk of hip fractures in older women. Future clinical trials should test whether interventions to decrease inflammatory marker levels reduces hip fractures.

Updated Projected Prevalence of Self-Reported Doctor-Diagnosed Arthritis and Arthritis-Attributable Activity Limitation Among US Adults, 2015-2040.

To update the projected prevalence of arthritis and arthritis‐attributable activity limitations among US adults, using a newer baseline for estimates.

Vital Signs: Prevalence of Doctor-Diagnosed Arthritis and Arthritis-Attributable Activity Limitation — United States, 2013–2015

Background In the United States, doctor-diagnosed arthritis is a common and disabling chronic condition. Arthritis can lead to severe joint pain and poor physical function, and it can negatively affect quality of life. Methods CDC analyzed 2013–2015 data from the National Health Interview Survey, an annual, nationally representative, in-person interview survey of the health status and behaviors of the noninstitutionalized civilian U.S. adult population, to update previous prevalence estimates of arthritis and arthritis-attributable activity limitations. Results On average, during 2013–2015, 54.4 million (22.7%) adults had doctor-diagnosed arthritis, and 23.7 million (43.5% of those with arthritis) had arthritis-attributable activity limitations (an age-adjusted increase of approximately 20% in the proportion of adults with arthritis reporting activity limitations since 2002 [p-trend <0.001]). Among adults with heart disease, diabetes, and obesity, the prevalences of doctor-diagnosed arthritis were 49.3%, 47.1%, and 30.6%, respectively; the prevalences of arthritis-attributable activity limitations among adults with these conditions and arthritis were 54.5% (heart disease), 54.0% (diabetes), and 49.0% (obesity). Conclusions and Comments The prevalence of arthritis is high, particularly among adults with comorbid conditions, such as heart disease, diabetes, and obesity. Furthermore, the prevalence of arthritis-attributable activity limitations is high and increasing over time. Approximately half of adults with arthritis and heart disease, arthritis and diabetes, or arthritis and obesity are limited by their arthritis. Greater use of evidence-based physical activity and self-management education interventions can reduce pain and improve function and quality of life for adults with arthritis and also for adults with other chronic conditions who might be limited by their arthritis.

Inflammatory Markers and Risk of Hip Fracture in Older White Women: The Study of Osteoporotic Fractures

Hip fractures are the most devastating consequence of osteoporosis and impact 1 in 6 white women leading to a two‐ to threefold increased mortality risk in the first year. Despite evidence of inflammatory markers in the pathogenesis of osteoporosis, few studies have examined their effect on hip fracture. To determine if high levels of inflammation increase hip fracture risk and to explore mediation pathways, a case‐cohort design nested in a cohort of 4709 white women from the Study of Osteoporotic Fractures was used. A random sample of 1171 women was selected as the subcohort (mean age 80.1 ± 4.2 years) plus the first 300 women with incident hip fracture. Inflammatory markers interleukin‐6 (IL‐6) and soluble receptors (SR) for IL‐6 (IL‐6 SR) and tumor necrosis factor (TNF SR1 and TNF SR2) were measured, and participants were followed for a median (interquartile range) of 6.3 (3.7, 6.9) years. In multivariable models, the hazard ratio (HR) of hip fracture for women in the highest inflammatory marker level (quartile 4) was 1.64 (95% confidence interval [CI], 1.09–2.48, p trend = 0.03) for IL‐6 and 2.05 (95% CI, 1.35–3.12, p trend <0.01) for TNF SR1 when compared with women in the lowest level (quartile 1). Among women with 2 and 3–4 inflammatory markers in the highest quartile, the HR of hip fracture was 1.51 (95% CI, 1.07–2.14) and 1.42 (95% CI, 0.87–2.31) compared with women with zero to one marker(s) in the highest quartile (p trend = 0.03). After individually adjusting for seven potential mediators, cystatin‐C (a biomarker of renal function) and bone mineral density (BMD) attenuated HRs among women with the highest inflammatory burden by 64% and 50%, respectively, suggesting a potential mediating role. Older white women with high inflammatory burden are at increased risk of hip fracture in part due to poor renal function and low BMD.

Hip Osteoarthritis and the Risk of All-Cause and Disease-Specific Mortality in Older Women: A Population-Based Cohort Study

To determine the risk of all‐cause and disease‐specific mortality among older women with hip osteoarthritis (OA) and to identify mediators in the causal pathway.

Correlates of trabecular and cortical volumetric bone mineral density of the radius and tibia in older men: The osteoporotic fractures in men study

Quantitative computed tomography (QCT) can estimate volumetric bone mineral density (vBMD) and distinguish trabecular from cortical bone. Few comprehensive studies have examined correlates of vBMD in older men. This study evaluated the impact of demographic, anthropometric, lifestyle, and medical factors on vBMD in 1172 men aged 69 to 97 years and enrolled in the Osteoporotic Fractures in Men Study (MrOS). Peripheral quantitative computed tomography (pQCT) was used to measure vBMD of the radius and tibia. The multivariable linear regression models explained up to 10% of the variance in trabecular vBMD and up to 9% of the variance in cortical vBMD. Age was not correlated with radial trabecular vBMD. Correlates associated with both cortical and trabecular vBMD were age (−), caffeine intake (−), total calcium intake (+), nontrauma fracture (−), and hypertension (+). Higher body weight was related to greater trabecular vBMD and lower cortical vBMD. Height (−), education (+), diabetes with thiazolidinedione (TZD) use (+), rheumatoid arthritis (+), using arms to stand from a chair (−), and antiandrogen use (−) were associated only with trabecular vBMD. Factors associated only with cortical vBMD included clinic site (−), androgen use (+), grip strength (+), past smoker (−), and time to complete five chair stands (−). Certain correlates of trabecular and cortical vBMD differed among older men. An ascertainment of potential risk factors associated with trabecular and cortical vBMD may lead to better understanding and preventive efforts for osteoporosis in men.

Inflammatory Markers and the Risk of Hip and Vertebral Fractures in Men: the Osteoporotic Fractures in Men (MrOS)

Cytokines play major roles in regulating bone remodeling, but their relationship to incident fractures in older men is uncertain. We tested the hypothesis that men with higher concentrations of pro‐inflammatory markers have a higher risk of fracture. We used a case‐cohort design and measured inflammatory markers in a random sample of 961 men and in men with incident fractures including 120 clinical vertebral, 117 hip, and 577 non‐spine fractures; average follow‐up 6.13 years (7.88 years for vertebral fractures). We measured interleukin (IL)‐6, C‐reactive protein (CRP), tumor necrosis factor alpha (TNFα), soluble receptors (SR) of IL‐6 (IL‐6SR) and TNF (TNFαSR1 and TNFαSR2), and IL‐10. The risk of non‐spine, hip, and clinical vertebral fracture was compared across quartiles (Q) of inflammatory markers using Cox proportional hazard models with tests for linear trend. In multivariable‐adjusted models, men with the highest (Q4) TNFa cytokine concentrations and their receptors had a 2.0–4.2‐fold higher risk of hip and clinical vertebral fracture than men with the lowest (Q1). Results were similar for all non‐spine fractures, but associations were smaller. There was no association between CRP and IL‐6SR and fracture. Men in the highest Q of IL‐10 had a 49% lower risk of vertebral fracture compared with men in Q1. Among men with ≥3 inflammatory markers in the highest Q, the hazard ratio (HR) for hip fractures was 2.03 (95% confidence interval [CI] 1.11–3.71) and for vertebral fracture 3.06 (1.66–5.63). The HRs for hip fracture were attenuated by 27%, 27%, and 15%, respectively, after adjusting for appendicular lean mass (ALM), disability, and bone density, suggesting mediating roles. ALM also attenuated the HR for vertebral fractures by 10%. There was no association between inflammation and rate of hip BMD loss. We conclude that inflammation may play an important role in the etiology of fractures in older men.

Meeting Physical Activity Guidelines and the Risk of Incident Knee Osteoarthritis: A Population‐Based Prospective Cohort Study

Knee osteoarthritis (OA) is a leading cause of disability and joint pain. Although other risk factors of knee OA have been identified, how physical activity affects incident knee OA remains unclear.