Magnitude of Potential Biases in a Simulated Case-Control Study of the Effectiveness of Influenza Vaccination
Magnitude of Potential Biases in a Simulated Case-Control Study of the Effectiveness of Influenza Vaccination
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DOI：
10.1093/cid/cir750
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发表时间：
2012-01-01
影响因子：
11.8
通讯作者：
Shay, David K.
中科院分区：
文献类型：
--
作者：
Ferdinands, Jill M.;Shay, David K.
背景资料。许多流感疫苗的有效性评估都是使用病例对照方法进行的。尽管几种形式的偏差可能会扭曲从病例对照研究得出的疫苗有效性的估计，但很少有人试图量化这些偏差的大小。我们估计了由病例对照研究得出的流感疫苗有效性值的潜在偏差的大小，这些因素包括基于流感疫苗状态的诊断检测的不同使用造成的偏差、不完美的诊断测试特征和混淆。一个决策树模型被用来模拟一个儿童流感疫苗有效性的病例对照研究。使用概率分布，我们改变了影响疫苗有效性估计的因素的值，包括诊断测试特征、疫苗覆盖率、接受流感诊断测试的可能性、因急性呼吸道感染住院的儿童患流感的可能性等。偏差被测量为在模拟病例对照研究中观察到的有效性与真实潜在有效性值之间的差异。结果与结论。我们发现，观察到的疫苗效力和真实疫苗效力之间的平均差异为-11.9%。在88%的模型迭代中，观察到的疫苗有效性低估了真实有效性。诊断试验的特异性与观察到的疫苗有效性显示出最强的相关性，其次是接受基于疫苗接种状况的诊断测试的可能性，以及因急性呼吸道感染住院的儿童患流感的可能性。我们的发现表明，我们检查的病例对照研究中的潜在偏差往往会导致对真正的流感疫苗效果的低估。
Background. Many influenza vaccine effectiveness estimates have been made using case-control methods. Although several forms of bias may distort estimates of vaccine effectiveness derived from case-control studies, there have been few attempts to quantify the magnitude of these biases.Methods. We estimated the magnitude of potential biases in influenza vaccine effectiveness values derived from case-control studies from several factors, including bias from differential use of diagnostic testing based on influenza vaccine status, imperfect diagnostic test characteristics, and confounding. A decision tree model was used to simulate an influenza vaccine effectiveness case-control study in children. Using probability distributions, we varied the value of factors that influence vaccine effectiveness estimates, including diagnostic test characteristics, vaccine coverage, likelihood of receiving a diagnostic test for influenza, likelihood that a child hospitalized with acute respiratory infection had influenza, and others. Bias was measured as the difference between the effectiveness observed in the simulated case-control study and a true underlying effectiveness value.Results and Conclusions. We found an average difference between observed and true vaccine effectiveness of -11.9%. Observed vaccine effectiveness underestimated the true effectiveness in 88% of model iterations. Diagnostic test specificity exhibited the strongest association with observed vaccine effectiveness, followed by the likelihood of receiving a diagnostic test based on vaccination status and the likelihood that a child hospitalized with acute respiratory infection had influenza. Our findings suggest that the potential biases in case-control studies that we examined tend to result in underestimates of true influenza vaccine effects.