Randomized Controlled Trials: Overview, Advantages and Disadvantages

In a controlled trial, the participants are put into different groups. Some get the new treatment (investigational group), others are in the control group. The control group might get a placebo (a treatment that looks like the investigational treatment but has no active medicine), or the current standard of care, especially in cancer trials.

In a randomized controlled trial, participants are randomly assigned to either the investigational group or the control group by a computer. Neither the researcher nor the participant chooses which treatment group the participant will be in. This way, the groups are balanced and fair with respect to factors like sex or age that could affect the results.

What are the advantages of a randomized controlled trial?

Controlled trials allow sponsors to compare outcomes for people in the investigational group with those who had either an existing treatment or no treatment. For an investigational treatment to be approved, clinical trials must show that the treatment can improve outcomes for patients.

Randomized controlled trials are often considered the gold standard in clinical research because they help prevent bias. Bias happens when the trial results are influenced by choices that people involved in the clinical trial might make, such as who gets which treatment. If participants are randomly assigned to each group, and the groups are well-balanced, then it is more likely that any differences between the groups are due to the treatments themselves.

What are the disadvantages of a randomized controlled trial?

From a participant’s perspective, the main disadvantage is that they do not get to choose which treatment they will get.

Often, especially when the trial involves a life-threatening condition with an existing treatment, all participants will get that standard treatment, no matter which group they are in. Participants in the investigational group will get standard treatment plus the new treatment, while those in the control group get only the standard-of-care treatment. The sponsors will check if adding the investigational treatment to the standard-of-care treatment improves outcomes.

From a research perspective, it can be harder to recruit participants for a randomized controlled trial. Because recruitment takes more effort, these trials often take longer to complete and are more expensive to run.

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