le Cessie Saskia, Nagelkerke Nico, Rosendaal Frits R, van Stralen Karlijn J, Pomp Elisabeth R, van Houwelingen Hans C
Department of Medical Statistics and Bioinformatics, S5-P, Leiden University Medical Center, P.O. Box 9600, 2300 RC Leiden, the Netherlands.
Am J Epidemiol. 2008 Nov 15;168(10):1204-10. doi: 10.1093/aje/kwn236. Epub 2008 Oct 3.
Multiple control groups in case-control studies are used to control for different sources of confounding. For example, cases can be contrasted with matched controls to adjust for multiple genetic or unknown lifestyle factors and simultaneously contrasted with an unmatched population-based control group. Inclusion of different control groups for a single exposure analysis yields several estimates of the odds ratio, all using only part of the data. Here the authors introduce an easy way to combine odds ratios from several case-control analyses with the same cases. The approach is based upon methods used for meta-analysis but takes into account the fact that the same cases are used and that the estimated odds ratios are therefore correlated. Two ways of estimating this correlation are discussed: sandwich methodology and the bootstrap. Confidence intervals for the pooled estimates and a test for checking whether the odds ratios in the separate case-control studies differ significantly are derived. The performance of the method is studied by simulation and by applying the methods to a large study on risk factors for thrombosis, the MEGA Study (1999-2004), wherein cases with first venous thrombosis were included with a matched control group of partners and an unmatched population-based control group.
病例对照研究中的多个对照组用于控制不同来源的混杂因素。例如，病例可与匹配的对照组进行对比，以调整多种遗传或未知生活方式因素，同时与未匹配的基于人群的对照组进行对比。针对单一暴露分析纳入不同的对照组会产生几个比值比估计值，所有这些估计值都仅使用了部分数据。在此，作者介绍了一种将来自多个针对相同病例的病例对照分析的比值比进行合并的简便方法。该方法基于用于荟萃分析的方法，但考虑到使用了相同的病例这一事实，因此估计的比值比是相关的。文中讨论了两种估计这种相关性的方法：三明治方法和自助法。得出了合并估计值的置信区间以及用于检验单独的病例对照研究中的比值比是否存在显著差异的检验方法。通过模拟以及将这些方法应用于一项关于血栓形成危险因素的大型研究（MEGA研究，1999 - 2004年）来研究该方法的性能，在该研究中，首次发生静脉血栓的病例与配偶匹配对照组以及未匹配的基于人群的对照组一起纳入研究。
