Warren Alpert Medical School of Brown University, Providence, RI, USA.
Brown University, Providence, RI, USA.
Trop Med Int Health. 2019 Jan;24(1):23-30. doi: 10.1111/tmi.13166. Epub 2018 Oct 24.
Fluid loss during Ebola virus disease (EVD) infections from gastrointestinal dysfunction leads to volume depletion. It is possible that high environmental temperatures may exacerbate volume depletion or interfere with the provision of medical care by providers in full personal protective equipment. We investigated the effect of environmental temperature on case fatality.
The International Medical Corps (IMC) operated five Ebola Treatment Units (ETUs) in Liberia and Sierra Leone during the 2014-2016 epidemic. Demographic and outcomes variables for 465 patients with EVD were sourced from a de-identified, quality-checked clinical database collected by IMC. Daily environmental temperature data for Liberia and Sierra Leone were collected from a publicly available database (Weather Underground). Mean daily environmental temperatures were averaged across each patient's ETU stay and environmental temperature thresholds were determined. Multiple logistic regression was utilised, with forward variable selection and threshold for entry of P < 0.1. Statistical significance was defined as P < 0.05. The following variables were analysed as potential confounders: age, sex, ETU, length of ETU operation and date of treatment.
Case fatality was 57.6% among patients diagnosed with EVD. Analysis of case fatality across environmental temperature quintiles indicated a threshold effect; the optimal threshold for average environmental temperature during a patient's ETU stay was determined empirically to be 27.4 °C (81.3 °F). Case fatality was significantly greater for patients with average environmental temperatures above the threshold (70.4%) vs. below (52.0%) (P < 0.001). In multiple regression, patients with average environmental temperature above the threshold during their ETU stay were significantly more likely to die than patients below the threshold (aOR = 2.5, 95% CI 1.6-3.8, P < 0.001). This trend was observed only among patients treated in white tent ETUs, and not in ETUs with aluminium roofs.
These findings suggest that an average environmental temperature above 27.4 °C (81.3 °F) during patients' ETU stay is associated with greater risk of death among patients with EVD. Further studies should investigate this effect. These results have potential implications for reducing case fatality through improved ETU construction or other temperature control methods within ETUs during future outbreaks.
埃博拉病毒病（EVD）感染期间因胃肠功能障碍导致的液体流失会导致血容量不足。环境温度较高可能会加重血容量不足或干扰医护人员在全身个人防护装备下提供医疗护理。我们研究了环境温度对病死率的影响。
国际医疗团（IMC）在 2014-2016 年埃博拉疫情期间在利比里亚和塞拉利昂运营了五个埃博拉治疗中心（ETU）。从 IMC 收集的经过身份验证和质量检查的临床数据库中获取了 465 名埃博拉病毒病患者的人口统计学和结局变量。从一个公共数据库（Weather Underground）收集了利比里亚和塞拉利昂的每日环境温度数据。计算每位患者在 ETU 住院期间的平均每日环境温度，并确定环境温度阈值。采用多元逻辑回归，进行正向变量选择和 P < 0.1 的进入阈值。统计学意义定义为 P < 0.05。分析了以下变量作为潜在混杂因素：年龄、性别、ETU、ETU 运行时间和治疗日期。
被诊断患有 EVD 的患者病死率为 57.6%。分析环境温度五分位数的病死率表明存在阈值效应；通过经验确定患者在 ETU 住院期间环境温度的最佳阈值为 27.4°C（81.3°F）。平均环境温度高于阈值的患者病死率明显高于低于阈值的患者（70.4% vs. 52.0%）（P < 0.001）。在多元回归中，ETU 住院期间平均环境温度高于阈值的患者死亡的可能性明显高于低于阈值的患者（aOR = 2.5，95%CI 1.6-3.8，P < 0.001）。这种趋势仅见于在白色帐篷 ETU 中接受治疗的患者，而在带有铝制屋顶的 ETU 中则未见。
这些发现表明，患者 ETU 住院期间平均环境温度高于 27.4°C（81.3°F）与 EVD 患者死亡风险增加有关。应进一步研究这一影响。这些结果对通过改进 ETU 建设或在未来暴发期间通过其他温度控制方法降低病死率具有潜在意义。
