A case study of non-inferiority testing with survival outcomes
This is a case study for a new class of nonparametric tests designed to assess evidence of non-inferiority ordering among multiple survival functions. The tests are devised for tree-structured orderings, as needed for the comparison of an experimental treatment to one or more alternative treatments. Applications to data from two non-inferiority trials are developed: 1) a two-armed trial for the treatment of liver cancer in which we find strong evidence of the non-inferiority of an experimental treatment (lenvatinib) to a standard treatment (sorafenib), and 2) a three-armed trial for the treatment of major depression in which we find strong evidence that an experimental treatment is both superior to placebo and non-inferior to a standard treatment. We implement the approach in R, and explain in detail how to carry out the analyses for 1) and 2).