[Non-inferiority studies efficacy and safety: review of methodological and statistical aspects in clinical trials and non-interventional studies with medicinal products.]

Non-inferiority studies are increasingly more common for introducing new medicines in the market. Despite being situations where the use of this study design is justified, there is not a common analytical approach on how to conduct them. Pursuing a rigorous methodology, both in the study conduction and in its disseminations, is critical to ensure robust results to enable regulatory agencies and clinicians to reach valid conclusions and decisions which ultimately will benefit clinical practice. Most of the published reviews focus on the efficacy outcomes of non-inferiority clinical trials. We are unaware of other reviews that goes beyond and includes specific aspects for non-interventional designs and for studies focused on safety. Moreover, this review provides a simple and practical perspective with a minimum mathematical content on this complex type of studies.