中文摘要：

目的：探讨交叉设计多中心临床试验中事件数资料的分析。方法：采用多水平Poisson回归模型,以重复测量作为第一水平,试验阶段作为第二水平,受试者作为第三水平,建立多水平Poisson回归模型。结果：多水平Poisson模型分析交叉设计数据,不但可以解决层次结构的问题,使用也较重复测量资料的方差分析更为灵活。结论：在交叉设计临床试验中,对于事件数资料,可以采用多水平Poisson回归模型。

英文摘要：

AIM： To find the method of analyzing counting data from multi-center crossover clinical trails. METHODS： Multilevel Poisson regression model was fitted with the repeated-measurements as the first level, stage as the second level and patient as the third level. RESULTS： Multilevel model is not only convenient to handle data with hierarchical structures, but also more flexible than traditional methods such as repeated-measurements ANOVA. CONCLUSION： Multilevel Poisson regression model could be used in the analysis of counting data from crossover clinical designs.