Department of Infectious Disease Epidemiology, Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London WC1E 7HT, United Kingdom.
Proc Natl Acad Sci U S A. 2023 Jul 25;120(30):e2217601120. doi: 10.1073/pnas.2217601120. Epub 2023 Jul 19.
Armed conflict, displacement and food insecurity have affected Adamawa, Borno, and Yobe states of northeast Nigeria (population ≈ 12 million) since 2009. Insecurity escalated in 2013 to 2015, but the humanitarian response was delayed and the crisis' health impact was unquantified due to incomplete death registration and limited ground access. We estimated mortality attributable to this crisis using a small-area estimation approach that circumvented these challenges. We fitted a mixed effects model to household mortality data collected as part of 70 ground surveys implemented by humanitarian actors. Model predictors, drawn from existing data, included livelihood typology, staple cereal price, vaccination geocoverage, and humanitarian actor presence. To project accurate death tolls, we reconstructed population denominators based on forced displacement. We used the model and population estimates to project mortality under observed conditions and varying assumed counterfactual conditions, had there been no crisis, with the difference providing excess mortality. Death rates were highly elevated across most ground surveys, with net negative household migration. Between April 2016 and December 2019, we projected 490,000 excess deaths (230,000 children under 5 y) in the most likely counterfactual scenario, with a range from 90,000 (best-case) to 550,000 (worst-case). Death rates were two to three times higher than counterfactual levels, double the projected national rate, and highest in 2016 to 2017. Despite limited scope (we could not study the situation before 2016 or in neighboring affected countries), our findings suggest a staggering health impact of this crisis. Further studies to document mortality in this and other crises are needed to guide decision-making and memorialize their human toll.
自 2009 年以来，武装冲突、流离失所和粮食不安全一直影响着尼日利亚东北部的阿达马瓦州、博尔诺州和约贝州（人口约 1200 万）。2013 年至 2015 年，局势升级，由于死亡登记不完整和实地准入有限，人道主义应对行动滞后，这场危机对健康的影响也无法量化。我们使用一种小区域估计方法来估计这场危机导致的死亡率，该方法规避了这些挑战。我们根据人道主义行为者实施的 70 次实地调查收集的家庭死亡率数据拟合了一个混合效应模型。模型预测因子取自现有数据，包括生计类型、主食谷物价格、疫苗接种地理覆盖范围和人道主义行为者的存在。为了准确预测死亡人数，我们根据被迫流离失所重建了人口基数。我们使用该模型和人口估计值来预测在观察到的条件下和不同假设的反事实条件下的死亡率，两者之间的差异提供了超额死亡率。在大多数实地调查中，死亡率都非常高，家庭净负迁移。2016 年 4 月至 2019 年 12 月，我们在最有可能的反事实情况下预测了 49 万人（5 岁以下儿童 23 万）的超额死亡人数，范围从 9 万（最佳情况）到 55 万（最坏情况）。死亡率比反事实水平高出两到三倍，是全国预计死亡率的两倍，在 2016 年至 2017 年期间最高。尽管范围有限（我们无法研究 2016 年之前或邻国受影响国家的情况），但我们的研究结果表明，这场危机对健康造成了惊人的影响。需要进一步研究记录这场危机和其他危机中的死亡情况，以指导决策并纪念其对人类造成的损失。
