Assessment of systematic bias in the estimates.

During 2010–2012, extreme food insecurity and famine in Somalia were estimated to account for 256,000 deaths. Since 2014 Somalia has experienced recurrent below-average rainfall, with consecutive failed rains in late 2016 and 2017 leading to large-scale drought, displacement and epidemics. We wished to estimate mortality across Somalia from 2014 to 2018, and measure the excess death toll attributable to the 2017–2018 drought-triggered crisis. We used a statistical approach akin to small-area estimation, and relying solely on existing data. We identified and re-analysed 91 household surveys conducted at the district level and estimating the crude (CDR) and under 5 years death rate (U5DR) over retrospective periods of 3–4 months. We captured datasets of candidate predictors of mortality with availability by district and month. We also reconstructed population denominators by district-month combining alternative census estimates and displacement data. We combined these data inputs into predictive models to estimate CDR and U5DR and combined the predictions with population estimates to project death tolls. Excess mortality was estimated by constructing counterfactual no-crisis scenarios. Between 2013 and 2018, Somalia’s population increased from 12.0 to 13.5 million, and internally displaced people or returnees reached 20% of the population. We estimated an excess death toll of 44,700 in the most likely counterfactual scenario, and as high as 163,800 in a pessimistic scenario. By contrast to 2010–2012, excess deaths were widespread across Somalia, including central and northern regions. This analysis suggests that the 2017–2018 crisis had a lower, albeit still very substantial, mortality impact than its 2010–2012 predecessor. Despite modest elevations in death rate, crisis conditions were widespread and affected a population of millions. Humanitarian response to drought-related crises in Somalia needs to be strengthened, target the most vulnerable and emphasise very early interventions.2010年至2012年间，索马里境内极端粮食不安全与饥荒状况据估计造成25.6万人死亡。2014年以来，索马里持续出现降雨量低于常年平均水平的情况，2016年末与2017年连续雨季失效引发大规模干旱、人口流离失所以及流行病暴发。本研究旨在估算2014年至2018年索马里的整体死亡率，并测算2017-2018年干旱触发的危机所导致的超额死亡人数。研究采用了与小区域估计（small-area estimation）相似的统计方法，且仅依托现有数据开展分析。我们梳理并重新分析了91项区级层面的家庭调查，这些调查在3至4个月的回顾周期内，分别估算了粗死亡率（crude death rate, CDR）与5岁以下儿童死亡率（under-5 death rate, U5DR）。我们收集了按区域与月份划分的死亡率预测因子数据集，并结合替代人口普查估算值与流离失所人口数据，重构了区级-月度的人口基数。随后将所有数据输入预测模型，以估算粗死亡率与5岁以下儿童死亡率，再结合人口估算值推算总死亡人数。超额死亡率通过构建无危机的反事实情景进行估算。2013年至2018年间，索马里总人口从1200万增长至1350万，国内流离失所者或回流人口占总人口的比例达20%。在最贴合实际的反事实情景中，我们估计超额死亡人数为44700人，而在悲观情景下这一数值最高可达163800人。与2010-2012年的危机不同，本次超额死亡事件在索马里全境广泛分布，涵盖中部与北部地区。本分析显示，尽管2017-2018年危机的死亡影响仍极为严峻，但相较于2010-2012年的危机仍相对更低。尽管死亡率仅出现小幅上升，但危机状况已广泛蔓延，影响了数百万人口。索马里针对干旱相关危机的人道主义响应亟需强化，应瞄准最脆弱群体，并强调尽早开展干预举措。