Watson Kelly M, Dasiewicz Alison Sb, Bassani Diego G, Chen Chun-Yuan, Qamar Huma, O'Callaghan Karen M, Roth Daniel E
Centre for Global Child Health, The Hospital for Sick Children, Toronto, Canada.
Department of Nutritional Sciences, University of Toronto, Toronto, Canada.
Curr Dev Nutr. 2024 Oct 28;8(12):104495. doi: 10.1016/j.cdnut.2024.104495. eCollection 2024 Dec.
Assessments of the efficacy of interventions to improve child growth are often based on differences in mean height-for-age -scores (HAZ) and stunting (HAZ<-2) in randomized controlled trials (RCTs). However, this approach does not account for children's starting skeletal age and does not enable assessment of the extent to which interventions optimized linear growth.
The objectives of this study were to develop and apply a new method using height-age to express linear growth effects in RCTs.
Longitudinal individual participant data (IPD) from a Bangladeshi trial cohort were used to compare height-age estimates derived from individual-level heights, mean raw height, or mean HAZ. Then, using mean height-age as a proxy for skeletal age, we developed the "proportion of maximal benefit" (PMB) metric to quantify intervention effects relative to optimal growth for children's starting skeletal age. Optimal growth occurs when height-age increases in parallel with chronologic age (i.e., PMB = 100%), whereas no effect (compared with control) corresponds to a PMB of 0%. Linear growth outcomes in 4 published RCTs of nutrition-specific interventions were re-expressed as mean height-age and PMB and compared with effects conventionally expressed as intervention-compared with-control mean differences (MD) in HAZ.
Mean height-age could be derived from any published estimate of mean raw height or mean HAZ; however, to calculate the PMB, height or HAZ data were required at both the beginning and end of the observation period. Interpretations of intervention effects were consistent when expressed as either the height-age MD or HAZ MD. In contrast, the PMB does not have a corresponding metric on the HAZ scale and, therefore, provided a new way to quantify intervention efficacy.
Height-age can be used as an alternative to HAZ to express intervention effects. The PMB has the advantage of conveying the extent to which an intervention improved average linear growth in relation to a biologically-defined benchmark.
在随机对照试验（RCT）中，对改善儿童生长的干预措施效果的评估通常基于年龄别身高均值评分（HAZ）和发育迟缓（HAZ<-2）的差异。然而，这种方法没有考虑儿童开始时的骨骼年龄，也无法评估干预措施在多大程度上优化了线性生长。
本研究的目的是开发并应用一种新方法，使用身高年龄来表达RCT中的线性生长效应。
来自孟加拉国试验队列的纵向个体参与者数据（IPD）用于比较从个体水平身高、平均原始身高或平均HAZ得出的身高年龄估计值。然后，使用平均身高年龄作为骨骼年龄的替代指标，我们开发了“最大益处比例”（PMB）指标，以量化相对于儿童起始骨骼年龄的最佳生长情况下的干预效果。当身高年龄与实际年龄平行增加时（即PMB = 100%），发生最佳生长，而无效果（与对照组相比）对应于PMB为0%。4项已发表的特定营养干预RCT中的线性生长结果被重新表达为平均身高年龄和PMB，并与传统上表示为干预组与对照组HAZ均值差异（MD）的效果进行比较。
平均身高年龄可以从任何已发表的平均原始身高或平均HAZ估计值中得出；然而，为了计算PMB，在观察期开始和结束时都需要身高或HAZ数据。当以身高年龄MD或HAZ MD表示时，对干预效果的解释是一致的。相比之下，PMB在HAZ量表上没有相应的指标，因此提供了一种量化干预效果的新方法。
身高年龄可以用作HAZ的替代指标来表达干预效果。PMB的优点是能够传达干预措施相对于生物学定义的基准在多大程度上改善了平均线性生长。
