Longitudinal Changes in Hip Geometry and Skeletal Muscle

这项研究将在来自全国妇女健康中心的一个大型多种族队列（N = 11，432）中进行。 倡议（WHI），其中包括一项观察性研究和四项临床试验。这一群体的年龄范围在50- 79岁的基线，它有多个少数民族：1583黑人，739西班牙裔和149美洲原住民 妇女到2005年，该队列的最长随访时间将为9年。双能X线吸收法（DXA）是 用于测量骨矿物质密度（BMD）和身体成分。随机临床试验和纵向 WIII研究的性质提供了一个独特的机会来研究：1）绝经激素的治疗效果 治疗（MHT）和钙加维生素D补充对髋关节结构几何形状的影响; 2）纵向变化 骨骼肌质量作为髋关节脆弱性的一个因素; 3）髋关节几何形状的平均值和变化率的种族差异 和肌肉质量。特殊的计算机软件将用于分析髋关节扫描的双能x线吸收测量法 （DXA）。横截面积、骨膜下宽度、估计的皮质内直径、估计的平均皮质厚度， 股骨颈、转子间和股骨干区域的屈曲比和截面模量， 评估。将使用磁共振成像（MRI）扫描作为参考，以校准全身和腿部骨骼 DXA亚区分析的肌肉测量。各年龄组中肌肉减少症（低肌肉量）的患病率 年龄和族裔群体将得到研究。将使用混合效应模型分析纵向数据。这一拟议 这项研究不是由WHI计划资助的。WHI将提供的资源包括DXA扫描、跌倒和骨折数据， 和协变量的信息。由于大部分数据收集工作已经或将会由世界卫生研究所负责， 在这项研究中，能够以成本效益的方式检验多个重要的科学假设。在这方面， 辅助研究将提高WIL计划的科学贡献。这项研究的意义在于， 可以证明骨结构分析的效用，除了骨量测量，了解种族 骨折风险的差异和/或用于评估药物治疗（即CaD）对骨健康的影响。 此外，如果发现肌肉变量与股骨近端的骨骼结构和跌倒风险有关， 那么进一步测试增加该区域肌肉质量的干预措施是否会防止髋关节炎可能是重要的。 骨折

This study will be conducted among a large multiethnic cohort (N = 11,432) from the nationwide Women's Health Initiative (WHI), which includes an observational study and four clinic trials. The age range of this cohort is between 50- 79 years at the baseline, and it has multiple minority groups: 1583 black, 739 Hispanic and 149 Native American women. The maximal follow-up time of this cohort will be 9 years by 2005. Dual-energy x-ray absorptiometry (DXA) is used to measure bone mineral density (BMD) and body composition. The randomized clinical trials and longitudinal nature of the WIll study provide a unique opportunity to investigate: 1) treatment effects of menopausal hormone therapy (MHT) and calcium plus vitamin D supplementation on hip structural geometry; 2) longitudinal changes in skeletal muscle mass as a factor in hip fragility; and 3) ethnic differences of mean and rates of changes in hip geometry and muscle mass. Special computer software will be used for analyzing hip scans by dual-energy x-ray absorptiometry (DXA). Cross-sectional area, subperiosteal width, estimated endocortical diameter, estimated mean cortical thickness, buckling ratio and section modulus at the femoral neck, at the intertrochanteric and the femoral shaft regions will be assessed. Magnetic Resonance Imaging (MRI) scans will be used as references to calibrate total and leg skeletal muscle measurements from DXA subregion analyses. Prevalence rates of sarcopenia (low muscle mass) among each age and ethnic group will be studied. Mixed Effects Models will be used to analyze the longitudinal data. This proposed study is not funded by the WHI program. Recourses that the WHI will provide include DXA scans, fall and fracture data, and information on covariates. Since the majority of data collection work has been or will be done by the WHI, we will be able to cost-effectively test multiple important scientific hypotheses in this study. The novel approaches in this ancillary study will enhance scientific contributions of the WIll program. The significance of the proposed study is that it may demonstrate the utility of bone structural analysis in addition to bone mass measurements for understanding ethnic differences in fracture risk and/or for assessing the effect of pharmacologic therapy (i.e. CaD) on bone health. Furthermore, if the muscle variables are found to be related to bone structure in the proximal femur and the risk of fall, then it may be important to further test whether interventions that increase muscle mass in this region will prevent hip fracture.