Bone Health of Obese Adolescents During Weight Loss

描述(由申请人提供)：儿童肥胖症流行提出了重要的临床和公共卫生问题，即肥胖和肥胖治疗对骨骼发育的影响。骨质疏松性骨折是老年人发病率和死亡率的主要原因。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的影响的大小和方向尚不清楚，部分原因是骨骼确定问题。肥胖的儿童和青少年可能有更高的骨折风险，这与基于成人数据的预期相反。这项研究的主要目的是：1)使用现有最准确的方法对肥胖和非肥胖青少年的骨健康进行表征和比较，以及2)调查综合行为体重控制计划对肥胖青少年骨健康的影响。目的1将采用病例对照设计，将88名肥胖青少年(年龄在10岁至14岁)的骨状况指标与51名当代非肥胖对照青少年的骨状况指标进行比较，这些指标将被招募进行随机肥胖治疗试验。在目标2中，88名肥胖青少年将参加为期12个月的随机试验，1：1分配，对综合的、团体的、基于家庭的行为体重控制计划与个性化营养教育(通常护理)进行比较。对于这两个目标，主要结果将是骨强度，通过应力-强度指数估计，并通过外周定量计算机断层扫描(PQCT)测量胫骨的一个承重部位。假设与非肥胖青少年相比，肥胖者的长度骨强度更高(目标1)，但与正常护理相比，随着体重减轻而下降(目标2)。第二个目标是评估肥胖和体重减轻对桡骨的骨强度和小梁骨的影响，以及肥胖和骨健康之间潜在的中介因素，如营养、体力活动和肌肉力量。与公共健康相关：肥胖和骨质疏松性骨折是两个严重且日益严重的公共健康问题。由于尚不清楚在达到最大骨量之前发展或接受肥胖治疗的青少年患骨质疏松症的风险是增加还是降低，这项研究将比较肥胖和非肥胖青少年的骨健康，并调查减肥计划对骨健康的影响。

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.