Comparisons between superiority and non-inferiority trials
Characteristics | Superiority trials | Non-inferiority trials |
Null hypothesis | New treatment not superior to standard treatment/placebo | New treatment inferior to standard treatment |
Alternative hypothesis | New treatment is better than standard treatment/placebo | New treatment non-inferior to standard treatment |
Non-inferior margin | Not applicable | Predetermined |
Sequential testing | Not possible | Can be performed |
Significance level | P<0.05 (two-sided) | P<0.025 (one-sided) |
Comparator | Standard treatment or placebo | Standard treatment (seldom placebo) |
Possible outcomes | 1. New treatment superior (or inferior) to standard treatment/placebo 2. Inconclusive | See figure 1 |
Subgroup analyses | Possible | Possible |