Why participate in clinical trials for endometriosis?

By Nicola Watson, Priscilla Fernandez, Ann Doust, Emma Cox, ASHLEIGH SYMINGTON, Lone Hummelshoj, and Andrew Horne

Clinical trials are a key research tool to investigate new ways to prevent, treat, or detect conditions, such as endometriosis.

Why are clinical trials important?

Clinical research is done only if doctors do not know whether a new treatment approach or test works best for certain illnesses or groups of people, and whether it is safe.

Doctors make treatment recommendations based on the best available research evidence, which highlights the importance of continuing health research in areas where information is limited.

Evidence is limited in the field of endometriosis

A JLA Priority Setting Partnership surveyed over 1200 patients with endometriosis and clinicians to identify questions asked about endometriosis that we don’t yet know the answers to [1].

  1. Can a cure be developed for endometriosis?
  2. What causes endometriosis?
  3. What are the most effective ways of educating healthcare professionals throughout the healthcare system resulting in reduced time to diagnosis and improved treatment and care of women with endometriosis?
  4. Is it possible to develop a non-invasive screening tool to aid the diagnosis of endometriosis?
  5. What are the most effective ways of maximising and/or maintaining fertility in women with confirmed or suspected endometriosis?
  6. How can the diagnosis of endometriosis be improved?
  7. What is the most effective way of managing the emotional and/or psychological and/or fatigue impact of living with endometriosis (including medical, non-medical and self-management methods)?
  8. What are the outcomes and/or success rates for surgical or medical treatments which aim to cure or treat endometriosis, rather than manage it?
  9. What is the most effective way of stopping endometriosis progressing and/or spreading to other organs (e.g. after surgery)?
  10. What are the most effective non-surgical ways of managing endometriosis-related pain and/or symptoms (medical/non-medical)?

What is a clinical trial?

A clinical trial is a research study carried out by scientists and doctors to find out if a new treatment, intervention, or test is safe and effective in people.  This could involve a new drug, diet, or medical device, and the trial will compare the effects of the new treatment with another, existing, treatment.

For the study to take place, people are asked to volunteer to become participants in trial. Depending on the trial, the people involved may be patients, healthy people, or both.

Why would I take part in a clinical trial?

Evidence shows that hospitals that are active in research and deliver clinical research trials and studies have better patient outcomes.

Patients admitted to these research hospitals have more confidence in the clinical staff and are better informed about their condition and medical care.

Some reasons given by participants in clinical trials explaining why they decided to participate in and contribute to research:

  • To help others (including family members who may potentially develop the same condition)
  • To add to the body of information available for patients
  • To receive the newest treatment
  • To receive additional care and support from the clinical research staff
  • To help advance medical knowledge

How does a clinical trial work?

In drug trials participants are often divided into different groups including one group that receives the drug being tested, at least one other group that receives an inactive substance (placebo / dummy pill), and a group that receives an existing treatment.

Trials investigating surgical interventions might divide participants into groups which aim to study a particular surgical approach or to assess the improvement of symptoms and quality of life following the surgery.

Researchers are able to assess the effects of the trial drug or intervention by asking participants to complete health-related questionnaires.

The process used to allocate the participants into the different groups is called randomisation.


Randomised Controlled Trials (RCTs) are where participants in the trial are divided into two or more groups, with each group receiving a different treatment. RCTs are considered the best way of comparing treatments.

The randomisation process equally distributes participants into the trial’s pre-defined groups to ensure there is not a big variation in particular characteristics between the different groups. This ensures there is no bias in the way participants are allocated to each group, for example sicker or younger patients being allocated to one group only, which could make the trial results unreliable.

Participants are allocated to a group based on chance alone – usually done via a computer. Together with blinding, randomisation removes bias and truly allows for a direct comparison between different groups in a trial.


‘Blinding’ is when a patient doesn’t know which treatment they have been given, including if they have not been treated or have been given a placebo.

A placebo is an inactive treatment or drug sometimes used in trials to allow the researchers see if the new treatment they are testing does any better than no treatment at all. ‘Blinding’ ensures that when participants complete trial questionnaires the answers they provide cannot be affected by any knowledge of the treatment they received.

In some clinical trials the research team and medical staff are also blinded and do not know what treatment individual patients are getting. This is referred to as a ‘double-blind’ trial, and prevents bias from the research team and medical staff.

It is a very important aspect of clinical trials to ensure sure that the results we get are true and unbiased – especially if future treatments are to be based on the results of the trial.

It is important to remember that the researchers do not know which treatment is better.

Deciding whether to participate in a clinical trial or not

When considering whether or not to take part in research, you and your doctor need to weigh the benefits against any risks and then decide what is best for you.

It is important for you to know that all trials have gone through a rigorous approval process by an ethical review board to ensure that you are not put at any undue risk and, although you may not experience any immediate benefit from the intervention you have received, you should not come to any harm.

All clinical trials must work to a plan (“a protocol”), which explains how all aspects of the trial will work.

Your routine clinical care is also not affected by any participation.

Frequently asked questions about being part of a clinical trial

What if I start participating in a trial but do not wish to continue?
Should you wish to, you can remove yourself from the trial at any point.

What if I need further medical treatment whilst I am in a trial?
Your health will always take priority over your involvement in a trial. If you need further treatment due to symptoms of your condition, or for a different reason, you will be prescribed this as you normally would. It is an important aspect of a trial to see how treatments work in the real world, and this will be recorded as part of the trial data.

For example, patients who take part in surgical endometriosis trials are usually still allowed to either maintain or start new medical treatments for their condition as recommended by their doctor.

I feel overwhelmed by the prospect of participating in a trial
Some patients already feel physically and emotionally drained by the impact of endometriosis and feel unable to cope with any additional commitments without a guarantee of a definite benefit.

This is totally understandable. In this situation –  to decide whether or not to participate -however, many participants have commented on the benefit of the extra support they have received from the research team throughout their trial experience.

I want to know what treatment I receive
Patients wish to (and are encouraged to) feel in control of their care, which may make the idea of blinding unsettling. Blinding, however, is an extremely important part of clinical trials, which contributes to the best quality data being obtained.

It is important to note that not all trials are blinded. In trials, that are blinded, it is usual to offer the opportunity for participants to find out which treatment they received at the end of the trial. However, if there is a need for you or your doctors to find out before the end of the trial what treatment you were given (for example if you need further medical treatment) this information will be provided.

I want to follow my doctor’s recommendation
We encourage patients to discuss treatment options with their doctor and make a decision together. If a doctor feels a particular trial could potentially be of benefit to the patient, a referral will be made to the research team. This allows the patient to have access to all treatment options and empowers them to make the decision, which is right for them.

Any further questions?

If you have questions about participating in clinical trials, which we have not addressed here, please refer to:

  1. Horne AW, et al. Top ten research priorities in the UK and Ireland. Lancet 2017;389:2191-92
See also


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