Randomized Controlled Trial (RCT): What Labels Mean
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Randomized controlled trial

Also called RCT, randomized clinical trial, randomised trial, controlled trial · Reviewed

Definition: A randomized controlled trial (RCT) is a study that splits people into groups by chance and gives each group something different, such as a drug, a placebo or another drug. The NCI says using chance makes the groups similar, so the effects of the treatments can be compared more fairly.

What FDA rules ask of a well-controlled study

The FDA regulation on adequate and well-controlled studies (21 CFR 314.126) lists, among other things:

  • a clear statement of the study's goals and how the results will be analyzed;
  • a design that allows a valid comparison with a control group;
  • a way of assigning people to groups that limits bias and makes the groups alike in age, sex, how severe the disease is and other drugs used;
  • steps to limit bias by the people in the study, the observers and the analysts, such as blinding.

The rule names five kinds of control: placebo, a different dose of the same drug, no treatment, a known effective drug, and historical records. It says placebo, dose and active-drug trials usually include randomization and blinding.

How it shows up on labels

The side-effect table on the Ozempic label pools two placebo-controlled trials in which 521 people took Ozempic for a mean of 32.9 weeks. Nausea was reported by 15.8% on 0.5 mg and 20.3% on 1 mg, against 6.1% on placebo. Reading the drug columns next to the placebo column is what the trial design makes possible.

Why it matters for your log

A personal log is not a trial: there is one person, no control group and nothing is assigned by chance. It is still a dated record of what you took and how you felt, which your prescriber can set next to the trial numbers on the label.

Read more on Dose Track: Ozempic side effects · Side effects from FDA labels · Weekly research roundups

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.
PlaceboA placebo is an inactive substance or other treatment that looks the same as, and is given the same way… Double-blindA double-blind study is a trial in which neither the people taking part nor the researchers know who is… Open-labelAn open-label study is one in which both the health providers and the patients know which drug or… Clinical trial phasesClinical trial phases are the steps a drug goes through in human testing. The FDA describes four: phase 1… Noninferiority trialA noninferiority trial tests whether a new treatment is not worse than an active treatment it is compared…

Frequently asked questions

What does randomized mean in a drug trial?+
It means people are put into the treatment groups by chance. The NCI says this makes the groups similar, so the treatments can be compared more fairly.
Does every randomized trial use a placebo?+
No. FDA rules also recognize trials that compare doses of the same drug, compare with no treatment, or compare with a known effective drug.

Sources

  1. NCI Dictionary of Cancer Terms: randomized clinical trial
  2. 21 CFR 314.126: adequate and well-controlled studies, Cornell LII
  3. Ozempic (semaglutide) US prescribing information, DailyMed

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