Feng Shuo, Sullivan Sheena G, Tchetgen Tchetgen Eric J, Cowling Benjamin J
Am J Epidemiol. 2021 Oct 1;190(10):1993-1999. doi: 10.1093/aje/kwab101.
Test-negative studies are commonly used to estimate influenza vaccine effectiveness (VE). In a typical study, an "overall VE" estimate based on data from the entire sample may be reported. However, there may be heterogeneity in VE, particularly by age. Therefore, in this article we discuss the potential for a weighted average of age-specific VE estimates to provide a more meaningful measure of overall VE. We illustrate this perspective first using simulations to evaluate how overall VE would be biased when certain age groups are overrepresented. We found that unweighted overall VE estimates tended to be higher than weighted VE estimates when children were overrepresented and lower when elderly persons were overrepresented. Then we extracted published estimates from the US Flu VE network, in which children are overrepresented, and some discrepancy between unweighted and weighted overall VE was observed. Differences in weighted versus unweighted overall VE estimates could translate to substantial differences in the interpretation of individual risk reduction among vaccinated persons and in the total averted disease burden at the population level. Weighting of overall estimates should be considered in VE studies in the future.
检测呈阴性的研究通常用于估计流感疫苗的有效性（VE）。在一项典型研究中，可能会报告基于整个样本数据的“总体VE”估计值。然而，VE可能存在异质性，尤其是按年龄划分。因此，在本文中，我们讨论了按年龄划分的VE估计值加权平均以提供更有意义的总体VE衡量指标的可能性。我们首先通过模拟来说明这一观点，以评估当某些年龄组占比过高时总体VE会如何产生偏差。我们发现，当儿童占比过高时，未加权的总体VE估计值往往高于加权VE估计值；而当老年人占比过高时，未加权的总体VE估计值则较低。然后，我们从美国流感VE网络中提取了已发表的估计值，该网络中儿童占比过高，并且观察到未加权和加权总体VE之间存在一些差异。加权与未加权总体VE估计值的差异可能会导致在接种疫苗人群个体风险降低的解释以及人群层面避免的疾病总负担方面产生重大差异。未来在VE研究中应考虑对总体估计值进行加权。
