[Abstract] Comparative effectiveness research (CER) has been regarded as a hot topic in health care recently.Many medicalresearchers currently deem CER as a potential powerful instrument for improving the quality of healthcare and cut medical cost. However， in the past， classic efficacy studies are always focusing on comparing one new intervention with placebo under complete controlled environment. Now CER turns to comparing different interventions directly in real world of routine practice. This article reviewed a series of literature about the design ......