Lancet. 2016 Oct 8;388(10053):1725-1774. doi: 10.1016/S0140-6736(16)31575-6.
Established in 2000, Millennium Development Goal 4 (MDG4) catalysed extraordinary political, financial, and social commitments to reduce under-5 mortality by two-thirds between 1990 and 2015. At the country level, the pace of progress in improving child survival has varied markedly, highlighting a crucial need to further examine potential drivers of accelerated or slowed decreases in child mortality. The Global Burden of Disease 2015 Study (GBD 2015) provides an analytical framework to comprehensively assess these trends for under-5 mortality, age-specific and cause-specific mortality among children under 5 years, and stillbirths by geography over time.
Drawing from analytical approaches developed and refined in previous iterations of the GBD study, we generated updated estimates of child mortality by age group (neonatal, post-neonatal, ages 1-4 years, and under 5) for 195 countries and territories and selected subnational geographies, from 1980-2015. We also estimated numbers and rates of stillbirths for these geographies and years. Gaussian process regression with data source adjustments for sampling and non-sampling bias was applied to synthesise input data for under-5 mortality for each geography. Age-specific mortality estimates were generated through a two-stage age-sex splitting process, and stillbirth estimates were produced with a mixed-effects model, which accounted for variable stillbirth definitions and data source-specific biases. For GBD 2015, we did a series of novel analyses to systematically quantify the drivers of trends in child mortality across geographies. First, we assessed observed and expected levels and annualised rates of decrease for under-5 mortality and stillbirths as they related to the Soci-demographic Index (SDI). Second, we examined the ratio of recorded and expected levels of child mortality, on the basis of SDI, across geographies, as well as differences in recorded and expected annualised rates of change for under-5 mortality. Third, we analysed levels and cause compositions of under-5 mortality, across time and geographies, as they related to rising SDI. Finally, we decomposed the changes in under-5 mortality to changes in SDI at the global level, as well as changes in leading causes of under-5 deaths for countries and territories. We documented each step of the GBD 2015 child mortality estimation process, as well as data sources, in accordance with the Guidelines for Accurate and Transparent Health Estimates Reporting (GATHER).
Globally, 5·8 million (95% uncertainty interval [UI] 5·7-6·0) children younger than 5 years died in 2015, representing a 52·0% (95% UI 50·7-53·3) decrease in the number of under-5 deaths since 1990. Neonatal deaths and stillbirths fell at a slower pace since 1990, decreasing by 42·4% (41·3-43·6) to 2·6 million (2·6-2·7) neonatal deaths and 47·0% (35·1-57·0) to 2·1 million (1·8-2·5) stillbirths in 2015. Between 1990 and 2015, global under-5 mortality decreased at an annualised rate of decrease of 3·0% (2·6-3·3), falling short of the 4·4% annualised rate of decrease required to achieve MDG4. During this time, 58 countries met or exceeded the pace of progress required to meet MDG4. Between 2000, the year MDG4 was formally enacted, and 2015, 28 additional countries that did not achieve the 4·4% rate of decrease from 1990 met the MDG4 pace of decrease. However, absolute levels of under-5 mortality remained high in many countries, with 11 countries still recording rates exceeding 100 per 1000 livebirths in 2015. Marked decreases in under-5 deaths due to a number of communicable diseases, including lower respiratory infections, diarrhoeal diseases, measles, and malaria, accounted for much of the progress in lowering overall under-5 mortality in low-income countries. Compared with gains achieved for infectious diseases and nutritional deficiencies, the persisting toll of neonatal conditions and congenital anomalies on child survival became evident, especially in low-income and low-middle-income countries. We found sizeable heterogeneities in comparing observed and expected rates of under-5 mortality, as well as differences in observed and expected rates of change for under-5 mortality. At the global level, we recorded a divergence in observed and expected levels of under-5 mortality starting in 2000, with the observed trend falling much faster than what was expected based on SDI through 2015. Between 2000 and 2015, the world recorded 10·3 million fewer under-5 deaths than expected on the basis of improving SDI alone.
Gains in child survival have been large, widespread, and in many places in the world, faster than what was anticipated based on improving levels of development. Yet some countries, particularly in sub-Saharan Africa, still had high rates of under-5 mortality in 2015. Unless these countries are able to accelerate reductions in child deaths at an extraordinary pace, their achievement of proposed SDG targets is unlikely. Improving the evidence base on drivers that might hasten the pace of progress for child survival, ranging from cost-effective intervention packages to innovative financing mechanisms, is vital to charting the pathways for ultimately ending preventable child deaths by 2030.
Bill & Melinda Gates Foundation.
千年发展目标4（MDG4）于2000年确立，促使各国做出了非凡的政治、财政和社会承诺，目标是在1990年至2015年间将5岁以下儿童死亡率降低三分之二。在国家层面，儿童生存改善的进展速度差异显著，这突出表明迫切需要进一步研究儿童死亡率加速下降或减缓下降的潜在驱动因素。《2015年全球疾病负担研究》（GBD 2015）提供了一个分析框架，以全面评估5岁以下儿童死亡率、5岁以下儿童按年龄和病因分类的死亡率以及不同时期按地理位置划分的死产情况的趋势。
借鉴全球疾病负担研究先前版本中开发和完善的分析方法，我们对195个国家和地区以及选定的次国家地理区域在1980 - 2015年期间按年龄组（新生儿、新生儿后期、1 - 4岁、5岁以下）的儿童死亡率进行了更新估计。我们还估计了这些地理区域和年份的死产数量和比率。采用高斯过程回归并对抽样和非抽样偏差进行数据源调整，以综合每个地理区域5岁以下儿童死亡率的输入数据。特定年龄死亡率估计通过两阶段年龄 - 性别划分过程生成，死产估计采用混合效应模型，该模型考虑了不同的死产定义和特定数据源偏差。对于GBD 2015，我们进行了一系列新颖的分析，以系统地量化不同地理区域儿童死亡率趋势的驱动因素。首先，我们评估了5岁以下儿童死亡率和死产的观察值与预期值水平以及年化下降率与社会人口指数（SDI）的关系。其次，我们研究了基于SDI的不同地理区域儿童死亡率记录值与预期值的比率，以及5岁以下儿童死亡率记录值与预期年化变化率的差异。第三，我们分析了不同时间和地理区域5岁以下儿童死亡率的水平和病因构成与SDI上升的关系。最后，我们将5岁以下儿童死亡率的变化分解为全球层面SDI的变化以及各国和各地区5岁以下儿童死亡主要原因的变化。我们按照《准确和透明健康估计报告指南》（GATHER）记录了GBD 2015儿童死亡率估计过程的每一步以及数据源。
2015年，全球5岁以下儿童死亡580万（95%不确定区间[UI] 570 - 600万），自1990年以来5岁以下儿童死亡人数减少了52.0%（95% UI 50.7 - 53.3%）。自1990年以来，新生儿死亡和死产下降速度较慢，2015年新生儿死亡人数减少了42.4%（41.3 - 43.6%）至260万（260 - 270万），死产减少了47.0%（35.1 - 57.0%）至210万（180 - 250万）。1990年至2015年期间，全球5岁以下儿童死亡率的年化下降率为3.0%（2.6 - 3.3%），未达到实现MDG4所需的4.4%的年化下降率。在此期间，58个国家达到或超过了实现MDG4所需的进展速度。在2000年MDG4正式颁布至2015年期间，另外28个在1990年未达到4.4%下降率的国家达到了MDG4的下降速度。然而，许多国家5岁以下儿童死亡率的绝对水平仍然很高，2015年有11个国家的死亡率仍超过每1000例活产100例。许多传染病导致的5岁以下儿童死亡显著减少，包括下呼吸道感染、腹泻病、麻疹和疟疾，这在很大程度上推动了低收入国家总体5岁以下儿童死亡率的下降。与传染病和营养缺乏症方面取得的进展相比，新生儿疾病和先天性异常对儿童生存的持续影响变得明显，尤其是在低收入和中低收入国家。我们发现，在比较5岁以下儿童死亡率的观察值与预期值以及5岁以下儿童死亡率变化的观察值与预期值时存在相当大的差异。在全球层面，我们发现从2000年开始5岁以下儿童死亡率的观察值与预期值出现分歧，到2015年观察到的趋势下降速度比仅基于SDI预期的要快得多。2000年至2015年期间，全球5岁以下儿童死亡人数比仅基于SDI改善预期的少1030万。
儿童生存方面取得了巨大、广泛的进步，在世界许多地方，进步速度比基于发展水平提高所预期的要快。然而，一些国家，特别是撒哈拉以南非洲的国家，2015年5岁以下儿童死亡率仍然很高。除非这些国家能够以非凡的速度加速减少儿童死亡，否则它们不太可能实现提议的可持续发展目标。完善关于可能加速儿童生存进步速度的驱动因素的证据基础，从具有成本效益的干预措施组合到创新融资机制，对于规划到2030年最终消除可预防儿童死亡的途径至关重要。
比尔及梅琳达·盖茨基金会。
