Heterogeneities in the case fatality ratio in the West African Ebola outbreak 2013–2016

Tini Garske, Anne Cori, Archchun Ariyarajah, Isobel M Blake, Ilaria Dorigatti, Tim Eckmanns, Christophe Fraser, Wes Hinsley, Thibaut Jombart, Harriet Mills, Gemma Nedjati-Gilani, Emily Newton, Pierre Nouvellet, Devin Perkins, Steven Riley, Dirk Schumacher, Anita Shah, Maria D Van Kerkhove, Christopher Dye, Neil M FergusonChristl A Donnelly

Research output: Contribution to journalArticle (Academic Journal)peer-review

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Abstract

The 2013–2016 Ebola outbreak in West Africa is the largest on record with 28 616 confirmed, probable and suspected cases and 11 310 deaths officially recorded by 10 June 2016, the true burden probably considerably higher. The case fatality ratio (CFR: proportion of cases that are fatal) is a key indicator of disease severity useful for gauging the appropriate public health response and for evaluating treatment benefits, if estimated accurately. We analysed individual-level clinical outcome data from Guinea, Liberia and Sierra Leone officially reported to the World Health Organization. The overall mean CFR was 62.9% (95% CI: 61.9% to 64.0%) among confirmed cases with recorded clinical outcomes. Age was the most important modifier of survival probabilities, but country, stage of the epidemic and whether patients were hospitalized also played roles. We developed a statistical analysis to detect outliers in CFR between districts of residence and treatment centres (TCs), adjusting for known factors influencing survival and identified eight districts and three TCs with a CFR significantly different from the average. From the current dataset, we cannot determine whether the observed variation in CFR seen by district or treatment centre reflects real differences in survival, related to the quality of care or other factors or was caused by differences in reporting practices or case ascertainment.
Original languageEnglish
Article number20160308
Number of pages9
JournalPhilosophical Transactions B: Biological Sciences
Volume372
Issue number1721
Early online date10 Apr 2017
DOIs
Publication statusPublished - 26 May 2017

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