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Randomized controlled trial

(or randomised control trial; RCT) is a type of scientific (often medical) experiment, where the people being studied are randomly allocated one or other of the different treatments under study. The RCT is the gold standard for a clinical trial. RCTs are often used to test the efficacy or effectiveness of various types of medical intervention and may provide information about adverse effects, such as drug reactions. Random assignment of intervention is done after subjects have been assessed for eligibility and recruited, but before the intervention to be studied begins.

Experimental study designs can provide the evidence needed to answer pertinent clinical questions. To study the efficacy of a treatment, there needs to be a control group, ideally in the context of a randomized controlled trial (RCT).

Although the call for evidence based practice in surgery is increasingly high on the agenda, most surgeons feel that the format of the randomized controlled trial is not suitable for surgery 1) 2).

Random allocation in real trials is complex, but conceptually, the process is like tossing a coin. After randomization, the two (or more) groups of subjects are followed in exactly the same way, and the only differences between the care they receive, for example, in terms of procedures, tests, outpatient visits, and follow-up calls, should be those intrinsic to the treatments being compared. The most important advantage of proper randomization is that it minimizes allocation bias, balancing both known and unknown prognostic factors, in the assignment of treatments.

The terms “RCT” and randomized trial are sometimes used synonymously, but the methodologically sound practice is to reserve the “RCT” name only for trials that contain control groups, in which groups receiving the experimental treatment are compared with control groups receiving no treatment (a placebo-controlled study) or a previously tested treatment (a positive-control study). The term “randomized trials” omits mention of controls and can describe studies that compare multiple treatment groups with each other (in the absence of a control group).

Similarly, although the “RCT” name is sometimes expanded as “randomized clinical trial” or “randomized comparative trial”, the methodologically sound practice, to avoid ambiguity in the scientific literature, is to retain “control” in the definition of “RCT” and thus reserve that name only for trials that contain controls. Not all randomized clinical trials are randomized controlled trials (and some of them could never be, in cases where controls would be impractical or unethical to institute). The term randomized controlled clinical trials is a methodologically sound alternate expansion for “RCT” in RCTs that concern clinical research; however, RCTs are also employed in other research areas, including many of the social sciences.


Phase 1 randomized controlled trial

Phase 2 randomized controlled trial

Phase 3 randomized controlled trial

Phase IV: Studies are done after the drug or treatment has been marketed to gather information on the drug's effect in various populations and any side effects associated with long-term use.

Unger CA, Barber MD. Studying surgical innovations: challenges of the randomized controlled trial. J Minim Invasive Gynecol 2015;22:573–82.
Ceelen WP. Clinical research in surgery: threats and opportunities. Eur Surg Res 2014;53:95–107.
randomized_controlled_trial.txt · Last modified: 2016/06/25 11:37 (external edit)