A clinical trial design that tests whether a new treatment is no worse than an active comparator by more than a pre-defined margin — rather than testing whether it is better (superiority). The 2021 NEJM psilocybin vs escitalopram trial was a non-inferiority study: psilocybin was found non-inferior to the SSRI on the primary QIDS-SR outcome, meaning it performed at least as well. This is a meaningful finding — not a consolation. Non-inferiority with fewer side effects and a shorter treatment course represents a clinically significant advantage.
Non-inferiority is a clinical trial design that tests whether a new treatment is no worse than an active comparator by more than a pre-defined margin — rather than testing whether it is better (superiority). The 2021 NEJM psilocybin vs escitalopram trial was a non-inferiority study: psilocybin was found non-inferior to the SSRI on the primary QIDS-SR outcome, meaning it performed at least as well. This is a meaningful finding — not a consolation. Non-inferiority with fewer side effects and a shorter treatment course represents a clinically significant advantage.
See: Psilocybin vs SSRIs (/guides/psilocybin-vs-ssris).
Understanding non-inferiority helps you read the NEJM trial correctly: psilocybin "as good as" escitalopram is a strong result, especially with a shorter course and different side-effect profile.