Abstract：
BACKGROUND: In low/middle-income countries, most nutritional assessments use the latest weights, without reference to growth trajectory.
OBJECTIVE: This study explores whether velocity, in addition to the latest weight, improves the prediction of wasting, stunting or mortality in the first two years of life.
METHODS: We analysed a combined data set with weight and height data collected monthly in the first year of 3447 children from Pakistan, Malawi, South Africa, with height and survival recorded till 24 months. The main exposures were weight-for-age z-score (WAZ) at the end of each 2-month period and weight velocity-for-age z-score (WVZ2) across that period. The outcomes were wasting, stunting or all-cause mortality in the next 1-2 months. As a sensitivity analysis, we also used WVZ over 6 months (WVZ6), with matching WAZ. Cox proportional hazard models with repeated growth measures were used to study the association between exposures and mortality. Mixed Poisson models were used for stunting and wasting.
RESULTS: Children who were already stunted or wasted were most likely to remain so. WVZ2 was associated with a lower risk of subsequent stunting (RR 0.95; 95% CI 0.93-0.96), but added minimal prediction (difference in AUC = 0.004) compared to a model including only WAZ. Similarly, WVZ2 was associated with wasting (RR 0.74; 95% CI 0.72-0.76) but the prediction was only marginally greater than for WAZ (difference in AUC = 0.015). Compared to WAZ, WVZ6 was less predictive for both wasting and stunting. Low WVZ6 (but not WVZ2) was associated with increased mortality (HR 0.75, 95% CI 0.67-0.85), but added marginal only prediction to a model including WAZ alone (difference in C = 0.015).
CONCLUSIONS: The key anthropometric determinant of impending wasting, stunting, and mortality appears to be how far below the normal range the child\'s weight is, rather than how they reached that position.
OBJECTIVE: This study explores whether velocity, in addition to the latest weight, improves the prediction of wasting, stunting or mortality in the first two years of life.
METHODS: We analysed a combined data set with weight and height data collected monthly in the first year of 3447 children from Pakistan, Malawi, South Africa, with height and survival recorded till 24 months. The main exposures were weight-for-age z-score (WAZ) at the end of each 2-month period and weight velocity-for-age z-score (WVZ2) across that period. The outcomes were wasting, stunting or all-cause mortality in the next 1-2 months. As a sensitivity analysis, we also used WVZ over 6 months (WVZ6), with matching WAZ. Cox proportional hazard models with repeated growth measures were used to study the association between exposures and mortality. Mixed Poisson models were used for stunting and wasting.
RESULTS: Children who were already stunted or wasted were most likely to remain so. WVZ2 was associated with a lower risk of subsequent stunting (RR 0.95; 95% CI 0.93-0.96), but added minimal prediction (difference in AUC = 0.004) compared to a model including only WAZ. Similarly, WVZ2 was associated with wasting (RR 0.74; 95% CI 0.72-0.76) but the prediction was only marginally greater than for WAZ (difference in AUC = 0.015). Compared to WAZ, WVZ6 was less predictive for both wasting and stunting. Low WVZ6 (but not WVZ2) was associated with increased mortality (HR 0.75, 95% CI 0.67-0.85), but added marginal only prediction to a model including WAZ alone (difference in C = 0.015).
CONCLUSIONS: The key anthropometric determinant of impending wasting, stunting, and mortality appears to be how far below the normal range the child\'s weight is, rather than how they reached that position.
摘要：
背景：在中低收入国家，大多数营养评估使用最新的重量，不参考增长轨迹。
目的：本研究探讨了速度，除了最新的重量，提高了浪费的预测，在生命的头两年发育迟缓或死亡。
方法：我们分析了一个综合数据集，其中包括在第一年每月收集的3447名巴基斯坦儿童的体重和身高数据，马拉维,南非,记录身高和生存率，直至24个月。主要暴露是每个2个月结束时的体重年龄z得分（WAZ）和该时期的体重速度年龄z得分（WVZ2）。结果浪费了，在接下来的1-2个月内发育迟缓或全因死亡。作为敏感性分析，我们还使用了超过6个月的WVZ（WVZ6），与WAZ相匹配。使用具有重复生长测量的Cox比例风险模型来研究暴露与死亡率之间的关联。混合泊松模型用于发育迟缓和消瘦。
结果：已经发育迟缓或浪费的儿童最有可能保持这种状态。WVZ2与随后发育迟缓的风险较低相关(RR0.95;95%CI0.93-0.96)，但与仅包括WAZ的模型相比，增加了最小的预测(AUC差异=0.004)。同样，WVZ2与消瘦相关（RR0.74;95％CI0.72-0.76），但预测仅略高于WAZ（AUC差异=0.015）。与WAZ相比,WVZ6对消瘦和发育迟缓的预测能力较低。低WVZ6(但非WVZ2)与死亡率增加相关(HR0.75,95%CI0.67-0.85),但只在仅包括WAZ的模型中添加了边际预测(C=0.015的差异)。
结论：即将消瘦的关键人体测量决定因素，发育迟缓,和死亡率似乎是孩子的体重低于正常范围，而不是他们是如何到达那个位置的。
目的：本研究探讨了速度，除了最新的重量，提高了浪费的预测，在生命的头两年发育迟缓或死亡。
方法：我们分析了一个综合数据集，其中包括在第一年每月收集的3447名巴基斯坦儿童的体重和身高数据，马拉维,南非,记录身高和生存率，直至24个月。主要暴露是每个2个月结束时的体重年龄z得分（WAZ）和该时期的体重速度年龄z得分（WVZ2）。结果浪费了，在接下来的1-2个月内发育迟缓或全因死亡。作为敏感性分析，我们还使用了超过6个月的WVZ（WVZ6），与WAZ相匹配。使用具有重复生长测量的Cox比例风险模型来研究暴露与死亡率之间的关联。混合泊松模型用于发育迟缓和消瘦。
结果：已经发育迟缓或浪费的儿童最有可能保持这种状态。WVZ2与随后发育迟缓的风险较低相关(RR0.95;95%CI0.93-0.96)，但与仅包括WAZ的模型相比，增加了最小的预测(AUC差异=0.004)。同样，WVZ2与消瘦相关（RR0.74;95％CI0.72-0.76），但预测仅略高于WAZ（AUC差异=0.015）。与WAZ相比,WVZ6对消瘦和发育迟缓的预测能力较低。低WVZ6(但非WVZ2)与死亡率增加相关(HR0.75,95%CI0.67-0.85),但只在仅包括WAZ的模型中添加了边际预测(C=0.015的差异)。
结论：即将消瘦的关键人体测量决定因素，发育迟缓,和死亡率似乎是孩子的体重低于正常范围，而不是他们是如何到达那个位置的。
