Introduction

Evans syndrome is a rare autoimmune condition caused by the immune system attacking the body's blood cells. Some of the hallmark signs of this condition are decreased blood cells (cytopenia), which can either be anaemia (decreased red cells) or thrombocytopenia (decreased platelets, which help the body form blood clots). This condition occurs in people of all ages and genders. Evans syndrome is chronic and often has a high relapse rate. 

People with this condition are at a higher risk of suffering from thrombotic events caused by clots such as heart attacks, strokes and deep vein thrombosis. In this article, we will explore whether these thrombotic events are due to the condition itself or the treatment plans. 

Pathophysiology of thrombosis in Evans syndrome

Haemolysis-related mechanisms

The anaemia in Evans syndrome is caused by a process called haemolysis. Haemolysis is when red blood cells rupture or break down. When this happens, heme is released into the bloodstream. This is a molecule that is released whenever red blood cells are destroyed. It has inflammatory properties and can also induce thrombotic events.¹ It does this by activating the coagulation cascade, a series of biochemical events that lead to the formation of a blood clot after inflammation or injury in the blood vessels.²

Treatment-related mechanisms

Another mechanism that might be responsible for the formation of clots in people with Evans syndrome is the treatments that they receive. 

One of the main medications that people with this condition receive is prednisolone. This is a type of steroid which is useful in effectively managing acute flares; however, it can increase the risk of thrombotic events. Studies have shown that short-term use of steroids can nearly triple one's risk of developing venous thromboembolism (blockage of a vein by a blood clot). 

Another treatment that is often used is intravenous immune globulin (IVIG). This is a medication made from human plasma that contains antibodies and can help increase the number of platelets. Although this is considered a safe treatment, clot formation has occurred as a rare side effect.^3,4,5

Clinical evidence of thrombotic events in Evans syndrome

Thrombotic events in people with Evans syndrome are a well-known complication that has been studied and published in several journals. In 1994, a case was published regarding a 24-year-old (assigned male at birth) diagnosed with Evans syndrome, who had recurrent deep vein thrombosis and subsequently needed amputation of one of his limbs. Additionally, a case was published in 2005 of a female 19 year old patient with this condition who also suffered a deep vein thrombosis of one of her lower limbs. 

Subsequently, thrombotic events have become a concern for doctors, particularly post-treatment. Venous thromboembolism has become a major post-operative complication in patients who have had splenectomies as surgical for this condition.⁶

Distinguishing hemolysis vs treatment as the major contributor

In order to effectively manage any thrombotic events that might occur, it is important to distinguish whether haemolysis or treatment modalities are responsible for the formation of the clots. 

Thrombotic events linked with hemolysis in Evans syndrome typically occur before any treatment has been initiated. Patients typically present with signs of organ damage, such as headaches in the case of strokes, blood in urine in patients with acute kidney injury and limb ischaemia (lack of blood flow to the limbs). 

Thrombotic events associated with treatment modalities often occur after treatment has commenced. Typical complications are deep vein thrombosis and venous thromboembolism following steroids and splenomectomy. 

Clinical implications

There are clinical implications associated with the increased thrombotic event risk in people with Evans syndrome. Risk stratification could be a useful process in managing people with this condition. This is the process of categorising people in different levels of risk, such as low, medium and high.⁷ Armed with this knowledge, clinicians could consider prophylactic anticoagulation therapy for people at high risk of developing clots. 

Regular monitoring could also be beneficial to treat any complications as soon as they occur. Coagulation markers are biochemical markers that can be detected through blood tests and help clinicians diagnose clots early. 

Additionally, it is important to accurately determine the dosage of any treatment modalities, such as prednisolone, in order to ensure that any thrombotic risk is kept at a minimum. 

Future directions

To better understand clot formation in Evans syndrome, additional research and studies are needed. Although there are a few case studies showing that clot formation is a complication of this condition, more extensive and detailed case studies are needed that have a wider selection of patients. 

Artificial Intelligence could also help clinicians in managing patients. This technology could be used to create risk prediction models that would be able to accurately predict one's risk of suffering from a thrombotic event. 

Additionally, safer treatment alternatives should be explored. Immunosuppressants could be trialled in people with Evans syndrome. As this condition is an autoimmune disease, using immunosuppressants could help treat it and reduce the number of acute flares. Blood transfusions are also a low-risk treatment that can be used to increase blood cell counts. 

Summary

Evans syndrome is an autoimmune condition characterised by decreased numbers of red blood cells and platelets. People with this condition are also at an increased risk of having thrombotic events caused by blood clots such as heart attacks, strokes and deep vein thrombosis. These thrombotic events can either be caused by hemolysis or treatment mechanisms. 

Case studies have been published in several journals, detailing these thrombotic events in people with Evans syndrome. However, there is a need for more extensive research into the increased risk of thrombotic events in these patients. 

It is also important for patients to be categorised into low, medium and high risk categories as this will help clinicians to manage these patients. Depending on their risk, prophylactic anticoagulation can be considered alongside regular monitoring. 

FAQs

Is Evans syndrome a rare condition?

Yes, Evans syndrome is a rare condition.

When is Evans syndrome’s awareness day?

 21st September is Evans Syndrome awareness day. 

What causes Evans syndrome?

 Evans syndrome is an autoimmune condition, meaning that one's immune system causes it.