Bone Health of Obese Adolescents During Weight Loss

描述（由申请人提供）：儿童肥胖流行引发了有关肥胖和肥胖治疗对骨骼发育影响的重要临床和公共卫生问题。骨质疏松性骨折是老年人发病和死亡的主要原因。然而，青春期后不久达到的峰值骨量是终生骨质疏松性骨折风险的关键决定因素。肥胖和体重减轻对儿童骨骼健康影响的大小和方向尚不清楚，部分原因是骨骼确定问题。肥胖儿童和青少年的骨折风险可能较高，这与成人数据的预期相反。拟议研究的主要目的是：1）使用最准确的方法描述和比较肥胖和非肥胖青少年的骨骼健康，2）调查综合行为体重控制计划对肥胖青少年骨骼健康的影响。目标 1 将使用病例对照设计来比较 88 名肥胖青少年（10 至 14 岁）的骨骼状况测量值，这些青少年将被招募进行随机肥胖治疗试验，并与 51 名当代非肥胖对照青少年进行相同的测量。对于目标 2，88 名肥胖青少年将参加一项为期 12 个月的随机试验，按 1:1 分配，进行全面的、团体的、基于家庭的行为体重控制计划与个体化营养教育（常规护理）。对于这两个目标，主要结果将是骨强度，通过应力强度指数进行估计，并通过承重部位胫骨的外周定量计算机断层扫描（pQCT）进行测量。假设与非肥胖青少年相比，肥胖青少年的骨强度会更高（目标 1），但与常规护理相比，骨强度会随着体重减轻而降低（目标 2）。次要目标是评估肥胖和体重减轻对桡骨骨强度、骨小梁以及肥胖与骨骼健康之间关联的潜在中介因素（例如营养、体力活动和肌肉力量）的影响。与公共卫生的相关性：肥胖和骨质疏松性骨折是两个重要且日益严重的公共卫生问题。由于尚不清楚在达到最大骨量之前发生肥胖或接受肥胖治疗的青少年患骨质疏松症的风险是否增加或减少，因此本研究将比较肥胖和非肥胖青少年的骨骼健康，并调查减肥计划对骨骼健康的影响。

DESCRIPTION (provided by applicant): The childhood obesity epidemic raises important clinical and public health questions about the effects of both obesity and obesity treatment on bone development. Osteoporotic fractures are a major cause of morbidity and mortality in the aged. However, peak bone mass, achieved shortly after puberty, is the key determinant of lifetime osteoporotic fracture risks. The size and direction of effects of obesity and weight loss on bone health in childhood are unclear, partly because of bone ascertainment issues. Obese children and adolescents may have elevated fracture risks, contrary to expectations based on adult data. Primary aims of the proposed study are to: 1) characterize and compare bone health of obese and non-obese adolescents using the most accurate methods available, and 2) investigate the impact of comprehensive behavior weight control program on the bone health of obese adolescents. Aim 1 will use a case-control design to compare bone status measures of 88 obese adolescents (ages 10 to 14 years), to be recruited for a randomized obesity treatment trial, with the same measurements as a group of 51 contemporary non-obese control adolescents. For Aim 2, the 88 obese adolescents will be enrolled in a 12-month randomized trial, with 1:1 assignment, of a comprehensive, group, family-based, behavioral weight control program vs. individualized nutrition education (usual care). For both aims the primary outcome will be bone strength, estimated by stress-strength index, and measured by peripheral quantitative computerized tomography (pQCT) at the tibia, a weight-bearing site. Hypotheses are that bone strength for length will be higher in the obese compared to the non-obese adolescents (Aim 1), but will decrease with weight loss compared to usual care (Aim 2). Secondary aims are to assess the impact of obesity and weight loss on bone strength at the radius, on trabecular bone and potential mediators of the association between obesity and bone health, such as nutrition, physical activity, and muscle strength. Relevance to Public Health: Obesity and osteoporotic fractures are two significant and increasing public health problems. As it is unclear if adolescents who develop or are treated for obesity before they reach maximum bone mass are at increased or decreased risk for osteoporosis, this study will compare bone health of obese and non-obese adolescents and investigate the impact of a weight loss program on bone health.