Obesity and non-communicable disease in Malaysia: an imaging study of 6000 adults in the Malaysian Cohort Study

在世界范围内，身体脂肪过多是糖尿病、心脏病和中风的主要原因。身体质量指数（BMI；定义为体重以公斤为单位除以身高以米为单位的平方）是世界卫生组织超重和肥胖定义的基础，BMI在25至30公斤/平方米之间归类为超重，超过30公斤/平方米为肥胖。然而，越来越多的证据表明，给定BMI的体脂水平可能因人群而异，这就提出了关于超重和肥胖普遍适用的基于BMI的指南的问题。虽然BMI在马来西亚经常被用来评估身体脂肪过剩，但没有大规模的成像研究直接测量身体脂肪及其分布，这将使我们更好地了解这一人群中身体成分与疾病结局之间的关系。从2006年到2012年，马来西亚政府发起的马来西亚队列研究招募了106527名35岁或以上的成年人。参与者完成了一份生活方式问卷，进行了身体测量，提供了血液样本，目前正在接受健康事件的跟踪调查。在6000名马来西亚队列参与者中，我们将使用英国生物银行（牛津大学纳菲尔德人口健康系协调的大型队列研究）制定的方案进行全身双能x射线吸收仪（DXA）成像（除了体脂百分比外，还提供体脂分布数据）。该影像亚研究将显著增强这一国家生物医学资源。使用DXA成像，本研究将可靠地评估马来西亚人口中用于估计身体成分（包括BMI、腰围和腰臀比）的传统测量方法与从DXA测量得出的绝对区域脂肪量之间的关系。然后，它将评估这些措施与糖尿病和心血管疾病风险之间的关系，为该人群中适当测量过量体脂的公共卫生指导提供信息，这些措施的理想“正常”范围，以及马来西亚不同种族群体的指导是否应有所不同。DXA成像也将显著增强马来西亚队列的潜力，以调查马来西亚肥胖的遗传和环境决定因素，以及它导致糖尿病和心血管疾病的生物学途径。并非所有超重或肥胖的人都会因超重而遭受不良后果，部分原因是脂肪分布的差异。事实上，根据马来西亚队列最近的报告，肥胖（基于BMI）和2型糖尿病的患病率在马来西亚的主要民族（马来人、印度人和华人）之间存在很大差异，而BMI只能部分解释这一点。因此，基于组织和器官特异性脂肪库，更好地了解种族间的风险，将使有限的资源更精确地定位于那些将获得最大利益的人。

Excess body fat is a major cause of diabetes, heart attacks and strokes, worldwide. Body-mass index (BMI; defined as weight in kilograms divided by height in meters squared) is the basis of the World Health Organisation's definition of overweight and obesity, with a BMI of between 25 and 30 kg/m2 classified as overweight, and over 30 kg/m2 as obese. However, there is increasing evidence that levels of body fat for a given BMI may vary between populations, raising questions regarding universally applied BMI-based guidelines for overweight and obesity. Although BMI is frequently used in Malaysia to assess excess body fat, there have been no large-scale imaging studies with direct measurements of body fat and its distribution which would allow us to understand better the relationship between body composition and disease outcomes in this population. From 2006-2012, The Malaysia Cohort study - initiated by the Malaysian government - recruited 106,527 adults aged 35 years or over. Participants completed a lifestyle questionnaire, underwent physical measurements, provided a blood sample and are now being followed for health events. In 6000 of The Malaysia Cohort participants, we will conduct whole-body Dual-energy X-ray Absorptiometry (DXA) imaging (which provides data on body fat distribution in addition to body fat percentage) using protocols established by the UK Biobank (a large cohort study co-ordinated by the Nuffield Department of Population Health, University of Oxford). This imaging sub-study will significantly enhance this national biomedical resource.Using DXA imaging, this study will reliably assess the relationship between conventional measures for estimating body composition (including BMI, waist circumference and waist-hip ratio) with the absolute regional fat masses derived from the DXA measurements in the Malaysian population. It will then assess the relationship between these measures and risk of diabetes and cardiovascular disease, to inform public health guidance on the appropriate measure of excess body fat in this population, the ideal 'normal' range of these measures, and whether guidance should vary for the different ethnic groups in Malaysia. DXA imaging will also significantly enhance the potential of The Malaysia Cohort to investigate the genetic and environmental determinants of obesity in Malaysia, and the biological pathways through which it causes diabetes and cardiovascular disease.Not all people who are overweight or obese suffer adverse consequence from their excess weight, in part due to differences in fat distribution. Indeed, as recently reported from The Malaysia Cohort, the prevalence of obesity (based on BMI) and type 2 diabetes is very divergent between the major ethnic groups in Malaysia (Malay, Indian and Chinese) and this is only partly explained by BMI. Therefore, a better understanding of the between-ethnic group risk, based on tissue and organ-specific fat depots, will enable more precise targeting of limited resources to those who will gain the most benefit.