Longitudinal Changes in Hip Geometry and Skeletal Muscle

产品说明：（由申请人提供）本研究将在来自全国妇女健康倡议（WHI）的大型多种族队列（N = 11，432）中进行，其中包括一项观察性研究和三项临床试验。该队列的基线年龄范围在50-79岁之间，有多个少数群体：1583名黑人，739名西班牙裔和149名美洲土著妇女。到2005年，该队列的最长随访时间将为9年。双能X射线吸收法（DXA）用于测量骨矿物质密度（BMD）和身体成分。WHI研究的随机临床试验和纵向性质为研究以下方面提供了独特的机会：1）激素替代疗法（HRT）以及钙和维生素D补充剂对髋关节结构几何形状的治疗效果; 2）骨骼肌质量的纵向变化作为髋关节脆性的一个因素; 3）髋关节几何形状和肌肉质量的平均值和变化率的种族差异。将使用专用计算机软件通过双能X线吸收测定法（DXA）分析髋关节扫描。将评估股骨颈、转子间和股骨干区域的横截面积、骨膜下宽度、估计的皮质内直径、估计的平均皮质厚度、屈曲比和截面模量。MRI扫描将用作参考，以校准DXA亚区分析的总骨骼肌、四肢骨骼肌和腿部骨骼肌测量值。将研究各年龄和种族组中肌肉减少症（低肌肉质量）的患病率。随机效应模型将用于分析纵向数据。这项拟议的研究不是由WHI计划资助的。WHI将提供的资源包括DXA扫描、跌倒和骨折数据以及协变量信息。由于大部分数据收集工作已经或将由WHI完成，我们将能够在本研究中以成本效益的方式测试多个重要的科学假设。这项辅助研究中的新方法将增强WHI计划的科学贡献。拟议的研究的意义在于，它可以证明除了骨量测量外，骨结构分析在了解骨折风险的种族差异和/或评估药物治疗（即HRT）对骨健康的影响方面的实用性。此外，如果发现肌肉变量是股骨近端骨结构和跌倒风险的强有力决定因素，那么制定干预措施以增加该区域的肌肉质量以预防髋部骨折可能很重要。

DESCRIPTION: (provided by applicant) 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 three 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 WHI study provide a unique opportunity to investigate: 1) treatment effects of hormone replacement therapy (HRT) and calcium and 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. MRI scans will be used as references to calibrate total, appendicular 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. Random 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 WHI 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. HRT) on bone health. Furthermore, if the muscle variables are found to be a strong determinant of bone structure in the proximal femur and the risk of fall, then it may be important to develop interventions to increase muscle mass in this region to prevent hip fracture.