The SITAR method of growth curve analysis for growth assessment in translational medicine and life course epidemiology

个别儿童的生长模式，如他们的连续测量（如体重或身高）与年龄绘制的生长曲线所表示的，可能提供有关他们早期情况的信息，或者相反，它可以预测他们在以后的生活中患疾病的风险，例如心脏病、中风或2型糖尿病。为了研究这一点，有必要以一种简单的方式总结每个人的成长曲线的形状，这样它的形状就可以与他们早期或后来的经历联系起来。SITAR生长曲线分析方法是一种新颖的方法，它将每个个体的生长曲线总结为三个数字，分别反映他们的尺寸（即与他人相比，他们的身高或身高，体重或体重），他们的生长速度（即他们的生长时间是否相对成熟或延迟，例如女孩的初潮年龄），以及速度（他们的生长速度与他人相比，例如在青春期）。此外，SITAR估计了一个平滑的平均增长曲线，可以与每个人的增长进行比较。令人惊讶的是，这个模型几乎解释了个体之间生长的所有可变性，因此它们的大小、节奏和速度可以被视为对其生长模式的完整总结。换句话说，当调整规模、节奏和速度时，它们的增长曲线都是一样的。然后，将个体的大小、节奏和速度值与他们之前或后来的经历联系起来，并寻找它们之间的联系，就很简单了。

The pattern of growth in individual children, as represented by their growth curve of successive measurements (e.g. weight or height) plotted against age, may be informative about their circumstances at earlier ages, or conversely it may predict their risk of disease later in life, for example heart disease, stroke or type 2 diabetes. To investigate this it is necessary to summarise the shape of each individual's growth curve in a simple way, so that its shape can be related to their earlier or later experiences. The SITAR method of growth curve analysis is a novel approach that does just this - it summarises each individual growth curve in just three numbers, reflecting respectively their size (i.e. tall or short, heavy or light, as compared to others), their growth tempo (i.e. whether they are relatively mature or delayed in their timing of growth, e.g. age of menarche in girls), and velocity (how fast they are growing compared to others, e.g. in puberty). In addition SITAR estimates a smooth average growth curve against which each individual's growth can be compared. The surprising thing is that this model explains nearly all of the variability in growth between individuals, so that their size, tempo and velocity can be viewed as a complete summary of their growth pattern. Put another way, when adjusted for size, tempo and velocity all their growth curves are the same. It is then simple to relate the values of size, tempo and velocity in individuals to their earlier or later experiences, and to look for links between them.