弹性匹配策略在分析基因与环境交互作用中的应用

以HER-2原癌基因Ile655Val多态性、吸烟与乳腺癌之间的关联研究为例,运用大样本近似原理计算检验效能,并通过逐步提高对照组中匹配因素的比例,探索弹性匹配策略在环境与基因交互作用分析中的应用价值及其效能计算方法 .HER-2基因多态和吸烟交互作用的检验效能在非匹配的病例对照研究中为30%,应用传统的频数匹配则提高为56%,进一步增加对照组的吸烟率,则能获得更高的效能值(power=74%).结论 :与非匹配或频数匹配的病例对照研究相比,应用弹性匹配的病例对照研究,能够显著增加环境与基因交互作用的检验效能和研究效率,此匹配策略尤其适用于人群中环境暴露率较低、环境暴露与基因易感性呈负向关联或匹配对照例数较少等情况.在研究设计时可充分权衡检验效能的提高与匹配成本的增加,从而选择最佳的匹配策略.

Application of flexible mashing strategy to detect gene-environment interactions for increasing the study power

Flexible matching has recently been proposed as a method of improving interactions efficiency. In this study, the concept of flexible matching has been introduced, and the applicability of this strategy has also been described based on the power calculation of interaction between HER-2 polymorphism and smoking with breast cancer. A large-sample approximation method is used to estimate the power and efficiency of gene-environment interactions. In the basic scenario, power of interaction between HER-2 polymorphism and smoking of unmatched case-control study appears to be 30% while in the frequency matching case-control study it is 56%. However, when increasing the smoking prevalence in controls, greater power can be obtained (power=74%). Conclusions: Flexible matching strategies can increase the power and efficiency of case-control studies to detect and estimate the gene-environment interactions when compared with traditional frequency matching and it is especially useful under those scenarios when low environmental exposure of population, adverse gene-environment interactions or less paired controls are seen. Optimal matching design should be made available by weighing the benefits and loss due to flexible matching.