What are they?

Randomised controlled trials (RCTs) are experimental studies that determine the effectiveness of a new intervention or treatment. They are typically considered the “gold standard” in research to identify a cause-and-effect relationship.

How does it work?

Participants in the trial are randomly assigned to one of two (or more) groups: the experimental group that receives the intervention and the comparison/control group that receives ‘usual’ care, no treatment, or a placebo. Depending on the study, the control group is not left without care if that would be unethical. During recruitment, it is important that neither the participants nor researchers can predict which group someone will be assigned to – this is called allocation concealment and helps to prevent bias. Randomisation is typically done by a computer. The groups are followed up at specific times throughout the study to find out how effective the experimental intervention is.

For example, as part of the EUmetriosis project, the DietAry interveNtion in ameliorating fertiliTy parameters in women with Endometriosis (DANTE) study is conducting a randomised controlled trial (RCT). Participants will be randomly allocated to one of two groups:

  • A 12-week anti-inflammatory diet based on Mediterranean diet principles (the experimental group)
  • No dietary changes (the control group)

This will take place before the beginning of controlled ovarian stimulation for IVF.

What is blinding?

Blinding may also be used in RCTs to further minimise bias and strengthen the credibility of a study. In a single-blind study, patients do not know which group they have been placed in. In a double-blind study, both patients and researchers/doctors do not know which group the patients are in. This helps to prevent bias from the researchers and/or medical team influencing the results of the study.

However, blinding may not always be feasible or appropriate in all RCTs. For example, in nutritional studies such as in the DANTE study, double-blinding is almost impossible, which is normal and does not reduce the scientific value of the study if other sources of bias are properly controlled. With a drug, it is relatively easy to provide a placebo that looks identical to the treatment being tested. But in the DANTE study, participants and clinicians will immediately see what is on the plate, so blinding is not feasible.

Why this matters?

Clinical practice is based on the best current research evidence to guide patient care. RCTs are one of the best ways to test whether a treatment works and is safe. By conducting RCTs in endometriosis, new treatments can be developed and care can be improved. Research findings can also help update clinical guidelines, ensuring that patients receive the most effective and up-to-date care.

Read more about EUmetriosis research on our news page.