Randomized controlled trial (RCT)

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A randomized controlled trial (RCT) is a quantitative research method often used in the healthcare setting.


RCT’s are performed by randomly assigning different interventions (or treatments) to study participants. The study participants must meet certain inclusion criteria before they are allowed to enter the study. Likewise, some prospective study participants may be excluded from the study if they possess certain characteristics or disease states which would bias the study results. The purpose of randomizing subjects into a control (or non-intervention) group and an intervention group is to ensure that known and unknown confounding factors are evenly distributed between the two groups. All study subjects are treated identically except for intervention or lack of intervention. RCT’s are generally “blinded” so that the investigators and study participants are unaware of the subjects’ treatment assignment. Maintaining patients in “intention to treat” arms of a trial retains the advantage of randomization, in the event that subjects withdraw from the study for any reason. Analysis of RCT’s focuses on estimating the size of the difference in predefined outcomes between intervention groups.

Lachin et al have stated that RCT’s are the most reliable form of scientific evidence in healthcare studies because they eliminate spurious causality and bias. RCT’s have become the basis for what is currently called evidence-based medicine (EBM).


The history of clinical trials dates back to approximately 600 B.C. when Daniel of Judah conducted what is probably the earliest recorded clinical trial. He compared the health effects of the vegetarian diet with those of a royal Babylonian diet over a 10-day period. The 1st th century saw major advances in clinical trials, including a highly-touted study from France published in 1836, which examined the practice of bloodletting in the treatment of pneumonia. (The trial found that this was an effective practice.)

Archie Cochrane also popularized the RCT.

Credit for the modern randomized trial usually goes to Sir Austin Hill. The Medical Research Council trials on streptomycin for the treatment of pulmonary tuberculosis are considered landmark trials that ushered in a new era of medicine. Since that time, the methodology of the randomized controlled trial has been increasingly accepted and the number of randomized controlled trials has grown significantly.

Principal Use

RCT’s are considered to be the most rigorous scientific method of determining whether a cause-effect relationship exists between an intervention and outcome. For that reason, they are often used in medicine, especially when new or alternative interventions are being compared to usual standard care. Also, they are frequently used to assess the cost effectiveness of an intervention.


Randomization ensures that there are no systematic differences between intervention groups in factors, known and unknown, that may affect outcome. The blinding design ensures that the preconceived views of subjects and investigators cannot systematically bias the assessment of outcomes. Intention to treat analysis maintains the advantages of random allocation, which may be lost if subjects are excluded from analysis through, for example, withdrawal or the necessity to change intervention because of unforeseen circumstances.


RCT’s may be limited by ethical considerations. For example, if patients are given an intervention which is thought to be inferior to other treatment, the trial could be considered unethical.

Patient recruitment may be difficult in some RCT’s. Once an intervention has become widespread and well-known to the public, potential study participants may be unwilling to be in a study looking at alternative treatments. Also, some potential study participants are not willing to take on the “guinea pig” role, because they perceive that role as being inferior. Thirdly, some potential study subjects do not like the idea that they will receive no treatment, as is the case with some trials with a placebo-control arm.

A significant shortcoming of RCT’s is that generally they are more costly and time consuming than other types of experimental studies. Sample size considerations and rigorous randomization and study design make these trials more demanding.

Examples in Informatics

  • Rotman, BL et al. A randomized controlled trial of a computer-based physician workstation in an outpatient setting implementation barriers to outcome evaluation. Journal of the American Medical Informatics Association 3340-348, 1 6.
  • Lester, WT et al. Randomized controlled trial of an informatics-based intervention to increase statin prescription for secondary prevention of coronary disease. Journal of General Internal Medicine 2122-2 , 1006.
  • Leung, GM et al. Randomised controlled trial of clinical decision support tools to improve learning of evidence based medicine in medical students. British Medical Journal 32710 0, 2003.

Randomized Controlled Trials (RCT)


Randomized Controlled Trial is a type of an experiment in which all subjects of the experiment are randomly assigned to groups to receive or not to receive a substance or intervention that is being studied. The result of the experiment is derived from the comparison of the control group results with results from the variable group.


Earliest mention of the idea of a controlled study can be found in the Book of Daniel 1:11-16 where Daniel has proposed and participated in the study that compared a group who ate “vegetables and water” for ten days with a group that ate “royal food and wine” from the table of Nebuchadnezzar the king of Babylon. The time frame puts this at around 600 B.C. The result of the experiment reviled that group who had vegetarian diet were better nourished than group who consumed royal food.

Principal use

According to Wikipedia, randomized control trials are mostly used by healthcare services and health technologies such as pharmaceuticals, medical devices or surgery. RCTs are mostly used for clinical studies. Educational social and judicial sectors of science also take advantage of RTCs


The main advantage of this method is in its name – randomization. Randomization, if done properly, eliminates bias from the study, it ensures that characteristics of participants will be evenly distributed across all groups that participate in the experiment.


According to Harald O. Stolberg et al: “During the past 10 years, randomized controlled trials have been the subject rather than the tool of important, albeit isolated, research efforts usually designed to generate empiric evidence to improve the design, reporting, dissemination, and use of randomized controlled trials in health care. Such studies have shown that randomized controlled trials are vulnerable to multiple types of bias at all stages of their work span.” Another disadvantage is the cost of the study. For the study to have more power its population has to be as large as possible which can be very costly.

Examples in medical informatics:

There are many different studies in Biomedical informatics that take advantage of Randomized Control Trials these are just a few of them:

  • BL Rotman, AN Sullivan, TW McDonald, BW Brown, P DeSmedt, D Goodnature, MC Higgins, HJ Suermondt, C Young and DK Owens A randomized controlled trial of a computer-based physician workstation in an outpatient setting: implementation barriers to outcome evaluation .
  • Ida Sim, , Ben Olasov and Simona Carini Department of Medicine, Program in Biological and Medical Informatics, University of California, 3333 California St., Suite 435 Q, San Francisco, CA 94143-1211, USA . Available online 8 April 2004. An ontology of randomized controlled trials for evidence-based practice: content specification and evaluation using the competency decomposition method.
  • William T. Lester, MD, MS, Richard W. Grant, MD, MPH, G. Octo Barnett, MD, Henry C. Chueh, MD, MS Massachusetts General Hospital, and Harvard Medical School, Boston, Mass, USA. Randomized Controlled Trial of an Informatics-based Intervention to Increase Statin Prescription for Secondary Prevention of Coronary Disease.


  • Canadian Institute of Health Research. Randomized Controlled Trials (2006-2007) (Archived)
  • Wikipedia. Randomized controlled trial.
  • Harald O. Stolberg, Geoffrey Norman and Isabelle Trop. Randomized Controlled Trials


  • Lachin, JM et al. Randomization in clinical trials conclusions and recommendations. Controlled Clinical Trials 4365-374, 1 88.
  • Sibbald, B. Understanding controlled trials Why are randomized controlled trials important? British Medical Journal 316201, 1 8.
  • Stolberg, HO et al. Randomized controlled trials. American Journal of Roentgenology 183153 -1544, 2004.