Managing clot risk is critical in adults with immune thrombocytopenia
Study suggests early disease control may help enable anticoagulation
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Adults with immune thrombocytopenia (ITP) may be at risk of developing blood clots, and prompt control of the disease may help anticoagulation (blood thinners) be started when needed, with long-term treatment considered for patients who remain at high risk, a French study found.
The study, “Incidence, Characteristics, and Management of Venous Thrombosis in Adult Patients With Immune Thrombocytopenia: Results From the Multicenter, Prospective Registry CARMEN-France,” was published in the American Journal of Hematology.
In ITP, the immune system mistakenly attacks platelets, which are needed for the blood to clot and stop bleeding after injury. As a result, people with ITP commonly experience easy bruising or excessive bleeding. Although this may seem contradictory, people with ITP are also at increased risk of developing blood clots in veins, known as venous thrombosis.
Treating ITP can become more complicated when patients also need blood thinners to prevent blood clots from forming or growing larger. Doctors must carefully balance the risk of bleeding from low platelet counts with the risk of blood clotting. “The management of ITP in the context of anticoagulation is challenging,” the researchers wrote.
How common blood clots are in adults with ITP
To better understand this challenge, the researchers analyzed data from the CARMEN-France registry (NCT02877706), which collects real-world information from multiple hospitals across France. The study included 1,303 adults newly diagnosed with ITP, with a median age of 62, who were followed over time to see how often venous thrombosis occurred. At the time of diagnosis, 791 patients (60.1%) had bleeding.
Over a median follow-up of 13.7 months, 53 patients developed venous thrombosis. The overall cumulative risk increased over time, from 2.6% after one year to 8.6% after five years. Most events (52.8%) occurred within the first three months after diagnosis. Among patients treated with thrombopoietin receptor agonists (TPO-RAs), which stimulate the bone marrow to produce more platelets, the risk was higher — 9.3% after one year and 13.4% after five years.
Of the 53 patients, 23 had a pulmonary embolism, which occurs when a blood clot travels to the lungs. Another 20 had blood clots in unusual locations, such as in the brain or abdominal veins. Nearly two-thirds (64.1%) had at least three risk factors for venous thrombosis. Common risk factors included age older than 50, prior blood clots, and exposure to corticosteroids or TPO-RAs.
Compared with patients who did not develop venous thrombosis, those who did generally had more severe ITP. They were more likely to have a history of blood clots (24.5% vs. 6.3%), secondary ITP triggered by an underlying condition (26.4% vs. 14.5%), and bleeding at diagnosis (77.4% vs. 60%). They were also more likely to have blood markers linked to clot risk and were more often treated with TPO-RAs or had undergone spleen removal surgery.
Anticoagulation and long-term clot prevention
All patients who developed venous thrombosis, except one, were treated with anticoagulation. Most (83%) first received heparin, an injectable blood thinner, while the others received oral anticoagulants. Many (56.6%) were later switched to oral treatment, particularly patients with antiphospholipid antibodies or antiphospholipid syndrome, which increases clot risk.
Some patients required only short-term treatment, while others remained on long-term anticoagulation because of ongoing risk factors. After venous thrombosis, ITP was mainly treated with TPO-RAs, corticosteroids, or rituximab, an antibody therapy that reduces immune activity. In many patients, TPO-RAs were temporarily stopped and restarted later. During follow-up, five patients (9.4%) developed a second blood clot, and one patient died from a pulmonary embolism.
“This study suggests the good benefit-to-risk ratio of promptly controlling ITP, including with maintenance of TPO-RAs initially, to allow the prompt initiation of a therapeutic dose of anticoagulation. Long-term anticoagulation should be considered for patients with persistent risk factors of [venous thrombosis],” the researchers wrote.
