Noninferiority trials

Noninferiority trials are intended to show that the effect of a new treatment is not worse than that of an active control by more than a specified margin. These trials have a number of inherent weaknesses that superiority trials do not: no internal demonstration of assay sensitivity, no single conservative analysis approach, lack of protection from bias by blinding, and difficulty in specifying the noninferiority margin. Noninferiority trials may sometimes be necessary when a placebo group can not be ethically included, but it should be recognized that the results of such trials are not as credible as those from a superiority trial.

非劣效性试验（Noninferiority trials）旨在证明，新治疗方案的疗效未劣于阳性对照（active control），且二者的疗效差距未超出预先设定的非劣效界值（noninferiority margin）。此类试验存在多项优效性试验（superiority trials）所不具备的固有缺陷：无法通过内部验证证实试验的分析灵敏度（assay sensitivity），不存在单一的保守分析范式，无法通过设盲（blinding）规避研究偏倚，且难以精准确定非劣效界值。当出于伦理合规性考量无法设置安慰剂对照组时，有时需采用非劣效性试验，但需明确此类试验的结果可信度不及优效性试验。