Early epidemiological assessment of the virulence of emerging infectious diseases: a case study of an influenza pandemic.
Early epidemiological assessment of the virulence of emerging infectious diseases: a case study of an influenza pandemic.
复制标题
DOI：
10.1371/journal.pone.0006852
复制
发表时间：
2009-08-31
期刊：
影响因子：
3.7
通讯作者：
Heesterbeek JA
中科院分区：
文献类型：
--
作者：
Nishiura H;Klinkenberg D;Roberts M;Heesterbeek JA
病死率（CFR），即传染病死亡人数与病例数的比率，提供了对毒力的评估。计算流行病期间累计死亡人数与病例数的比率往往会导致有偏差的CFR。本研究开发了一种简单的方法，以获得一个无偏的估计确认CFR（cCFR），仅使用确诊病例作为分母，在流行病的早期阶段，即使只有少数死亡。我们的方法通过一个低估因子来调整偏倚的cCFR，该因子由症状发作至死亡的时间来告知。我们首先通过使用已知的无偏cCFR估计分析香港（2003年）的严重急性呼吸综合征爆发来检验该方法，然后调查美国和加拿大（2009年）已发表的新型猪源甲型H1N1流感病毒感染的流行病学数据集。由于仅观察到少数死亡不允许估计从发病到死亡的时间分布，因此通过敏感性分析解决了不确定性。流感的无偏cCFR的最大似然估计值可能在假设参数空间内的0.16-4.48%范围内，存在低估因素。对流感的估计表明，毒力与墨西哥的早期估计相当。即使没有死亡病例，我们的模型也允许估计cCFR的保守上限。虽然人们必须记住，整个人群的cCFR容易受到亚群之间的差异和诊断不足的影响，但我们的方法对于在流行病的早期阶段评估毒力以及告知政策制定者和公众是有用的。
The case fatality ratio (CFR), the ratio of deaths from an infectious disease to the number of cases, provides an assessment of virulence. Calculation of the ratio of the cumulative number of deaths to cases during the course of an epidemic tends to result in a biased CFR. The present study develops a simple method to obtain an unbiased estimate of confirmed CFR (cCFR), using only the confirmed cases as the denominator, at an early stage of epidemic, even when there have been only a few deaths. Our method adjusts the biased cCFR by a factor of underestimation which is informed by the time from symptom onset to death. We first examine the approach by analyzing an outbreak of severe acute respiratory syndrome in Hong Kong (2003) with known unbiased cCFR estimate, and then investigate published epidemiological datasets of novel swine-origin influenza A (H1N1) virus infection in the USA and Canada (2009). Because observation of a few deaths alone does not permit estimating the distribution of the time from onset to death, the uncertainty is addressed by means of sensitivity analysis. The maximum likelihood estimate of the unbiased cCFR for influenza may lie in the range of 0.16–4.48% within the assumed parameter space for a factor of underestimation. The estimates for influenza suggest that the virulence is comparable to the early estimate in Mexico. Even when there have been no deaths, our model permits estimating a conservative upper bound of the cCFR. Although one has to keep in mind that the cCFR for an entire population is vulnerable to its variations among sub-populations and underdiagnosis, our method is useful for assessing virulence at the early stage of an epidemic and for informing policy makers and the public.
登录
查看更多内容
影响因子：
--
作者：
Nishiura, Hiroshi
通讯作者：
Nishiura, Hiroshi
影响因子：
2.6
作者：
Cameron, AR;Baldock, FC
通讯作者：
Baldock, FC
DOI：
10.1016/s0140-6736(03)13410-1
发表时间：
2003-05-24
期刊：
Lancet (London, England)
影响因子：
--
作者：
Donnelly CA;Ghani AC;Leung GM;Hedley AJ;Fraser C;Riley S;Abu-Raddad LJ;Ho LM;Thach TQ;Chau P;Chan KP;Lam TH;Tse LY;Tsang T;Liu SH;Kong JH;Lau EM;Ferguson NM;Anderson RM
通讯作者：
Anderson RM
影响因子：
11.8
作者：
Brundage JF;Shanks GD
通讯作者：
Shanks GD
DOI：
10.1056/nejmp0904380
发表时间：
2009-07-09
期刊：
The New England journal of medicine
影响因子：
--
作者：
Lipsitch M;Riley S;Cauchemez S;Ghani AC;Ferguson NM
通讯作者：
Ferguson NM