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Ask your doctor about participating in a clinical trial, says Dr Catherine Bagot

Dr Catherine Bagot is a consultant haematologist who works in the West of Scotland Adult Haemophilia Comprehensive Care Centre.  She talks about how treatments for haemophilia have evolved in recent years and why people with haemophilia should ask about participating in clinical trials.

Haemophilia A or B occurs when you have a shortage of a clotting factor in your blood, or when the clotting factor doesn’t work normally. This means that whenever a blood vessel is damaged it is difficult for your blood to clot properly. This can result in bleeds in muscles and joints and occasionally the brain.  Around one in 5,000 men suffer from Haemophilia A and one in 30,000 men from Haemophilia B.

When I first got involved in haemophilia research, the standard treatment was regular injections of the clotting factor that haemophiliacs lack, into a vein. This is known as prophylaxis. However, these injections had to be done often – 2-3 times a week.

Nowadays, we are seeing clotting factor products which don’t need to be injected as often. These aim to increase the time that the body takes to remove the clotting factor from the bloodstream. This means they work for longer after being injected.

I’m involved in research into new treatments for haemophilia A and B that work in a different way. To make sure your blood doesn’t get too thick, our bodies naturally contain anticoagulants which prevent the blood from clotting too much. Instead of treating people with haemophilia by injecting the clotting factor that they are missing, these treatments work by either reducing the bodies’ ability to produce these natural anticoagulants, or prevent them from working. These treatments, which are still being researched, can be given less often than clotting factors, and they don’t need to be injected into a vein, but under the skin, which can be more convenient to administer.  

I’m also involved in research into gene therapies for Haemophilia A and B, which aim to give back the bodies’ ability to produce the clotting factor by itself. Gene therapy has the potential to prevent the need to inject yourself at all, or to reduce those injections drastically. There are a number of different types of gene therapy for haemophilia and some are at earlier stages of development than others. Excitingly, it is possible that, as a result of data from clinical trials, gene therapies for haemophilia A and B may become available in the next few years for some patients.  

The last ten years have really revolutionised haemophilia treatment, and that is all down to clinical trials and the patients with haemophilia who kindly agree to take part in them. These medicines would never have been discovered and become available to patients with haemophilia  if it wasn’t for clinical trials and patients being willing to participate in them.

Finally, as a doctor, when you run a clinical trial, you sometimes don’t know if your patients will benefit. And if they do, it might be years later. But in the trials I have been involved with for haemophilia, I have seen some people benefit in a very short space of time. I’ve heard some patients describe their participation in a clinical trial as life-changing. I’d like to see as many people as possible get that opportunity and so would really encourage anyone with haemophilia to ask their doctor if they might be a good candidate to participate in a trial.


Clinical trials are currently running at the West of Scotland Adult Haemophilia and Thrombosis Centre for patients with Haemophilia B. For more information on clinical trials for haemophilia A and B throughout the UK, see the Haemophilia Society website.  

PLEASE NOTE: Participating in a clinical trial may or may not be appropriate or beneficial for a number of reasons. Clinical trials use criteria to decide who can participate, including medical and treatment histories.

Not all clinical trials lead to a new or better treatment, as the treatment being tested may not work or have worse side effects than existing treatments. If you are thinking of joining a clinical trial, the researchers delivering it should explain these points before you agree to participate.


  • Rare diseases

Last modified: 20 September 2023

Last reviewed: 20 September 2023