Noninferiority Trial: Testing "Not Worse Than"
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Noninferiority trial

Also called non-inferiority trial, non-inferior, active-controlled trial, active comparator · Reviewed

Definition: A noninferiority trial tests whether a new treatment is not worse than an active treatment it is compared with. The NCI says these trials are sometimes done when a placebo cannot be used. They do not test whether the new treatment is better.

What FDA rules say

21 CFR 314.126 recognizes an active treatment control for when giving a placebo or no treatment would go against the patient's interest. When the aim is to show the two drugs are similar, the rule says the study report should assess whether the study could have detected a difference, because similar results can mean both drugs worked or that neither did.

An example: Endometrin

  • Endometrin is a progesterone vaginal insert used in fertility treatment.
  • In the main study, both 100 mg twice daily and three times daily were non-inferior to the active comparator for pregnancy rates, which were 39% and 42%.
  • In women aged 35 to 42, and in those with an FSH of 10 to 15 IU/L, pregnancy rates did not meet the non-inferiority criteria.
  • The label says efficacy in women 35 and older has not been clearly established.

Why it matters for your log

"Not worse than" is not "better than." When a comparison page or ad cites a trial, the type of trial tells you which claim it can support. Logging which product and schedule you use keeps your record clear if your plan changes.

Read more on Dose Track: Endometrin side effects · Crinone side effects · Crinone vs Endometrin · Prometrium vs Crinone

General education drawn from labels and published studies, not personal medical advice. Your prescriber, pharmacist and the label that came with your product are the final word.
Randomized controlled trialA randomized controlled trial (RCT) is a study that splits people into groups by chance and gives each… PlaceboA placebo is an inactive substance or other treatment that looks the same as, and is given the same way… Clinical trial phasesClinical trial phases are the steps a drug goes through in human testing. The FDA describes four: phase 1… FSH (follicle-stimulating hormone)FSH (follicle-stimulating hormone) is a hormone made by the pituitary gland. In men, MedlinePlus says FSH…

Frequently asked questions

What does non-inferior mean?+
It means a trial showed the new treatment was not worse than the active treatment it was compared with. It does not mean the new treatment was better.
Why not compare with a placebo?+
The NCI says non-inferiority trials are sometimes done when a placebo cannot be used, and FDA rules allow an active comparison when a placebo would go against the patient's interest.

Sources

  1. NCI Dictionary of Cancer Terms: non-inferiority trial
  2. 21 CFR 314.126: adequate and well-controlled studies, Cornell LII
  3. Endometrin (progesterone) vaginal insert US prescribing information, DailyMed

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