What are clinical trials?

Clinical trials, also called clinical studies or trials, are experimental studies (which carry out some intervention) in humans.

Clinical trials bring the highest strength of evidence in therapeutic studies, namely, in studies that seek to evaluate certain therapies, including surgical treatments. As an example, the study carried out by Azevedo et al. at: https://www.scielo.br/j/abcd/a/Fz5n96WdcMJXvfs5HF3XYNQ/?lang=en. The authors compare mesh fixation in the inguinal hernia (staples vs. glue vs. no fixation).

We say that clinical trials are controlled when they compare two or more therapies (when there is a control group).

We say that they are randomized if the participants are assigned to each of the groups (intervention or control group) at random.

We say that they are double-blinded if participants and researchers do not know which group each participant was allocated to (intervention or control group)

Clinical trials can also be used for prophylactic studies, namely, studies that evaluate a given intervention to prevent disease. Perhaps the most classic example is vaccines. Vaccines prevent the onset of certain infectious and contagious diseases. Studies that compare intervention with a given vaccine with a placebo, for example, are controlled clinical trials. A trial comparing fundoplication vs. PPI for cancer prevention in patients with Barrett's esophagus is another example of a prophylactic controlled trial.

This text was written by:

Francisco Tustumi,

FMUSP Digestive System Surgeon

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