EBM Consult

Randomized Controlled Trial (RCT)


    • A prospective study where patients from a population of interest are randomly assigned to either a experimental (treatment) or a control group and then are followed up a specific time intervals to collect data on the outcomes of interest.
    • Patients in the control group usually receive a placebo or comparative treatment generally considered already part of the standard of care.
    Study Diagram

    Randomized Controlled Trial RCT Design

    • Considered the gold standard for helping to explain an effect
    • When appropriate randomization has occurred, this design allows for washout of most population bias
    • Reduced influence by confounders because they can be controlled for by the investigators
    • Reduced variability in the outcome(s) being measured, thus increasing the precision of estimation (assumes proper control of confounders)
    • Easier to blind patients than observational studies

    • Generally more time consuming
    • Tend to be more expensive

    1. Noordij M et al. Study designs in clinical research. Nephron Clin Pract 2009;113(3):c218-21.
    2. Tinmouth A et al. Interventional trials: an overview of design alternatives. Transfusion 2007;47:565-67.
    Editors & Reviewers


    • Anthony J. Busti, MD, PharmD, FNLA, FAHA

    Last Reviewed:  July 2015