Study: Thrombotic Events Increase Mortality Risk for People With Polycythemia Vera or Essential Thrombocythemia

Study adds to the evidence that reducing the risk of blood clots should be one of the main goals of managing these myeloproliferative disorders. Monitoring cholesterol levels may be especially important.

People with polycythemia vera and essential thrombocythemia, two of the more common forms of myeloproliferative neoplasms, have a tendency to develop blood clots that can lead to heart attacks and strokes. To reduce that risk, patients are often prescribed aspirin as a way to make their platelets less “sticky.” Even so, a well-documented risk of blood clots with possibly severe cardiovascular events remains.

What is less well researched are the outcomes for the people with polycythemia vera and essential thrombocythemia who have had a stroke or heart attack. Naveen Pemmaraju, M.D., of the University of Texas MD Anderson Cancer Center, and his colleagues helped fill that void with a study compared people with polycythemia vera and essential thrombocythemia who have a had a “thrombotic event” to those that haven’t. The most common thrombotic events were ischemic strokes, myocardial infractions and transient ischemic attacks (TIAs).

Perhaps not surprisingly, they found a significantly higher mortality risk among those who had a thrombotic event compared to those who didn’t. Their results, which they reported in the journal Leukemia Research in February, show that the mortality risk was increased by 18% among people with polycythemia vera who had a thrombotic event compared to those who didn’t. Among those with essential thrombocythemia, the mortality risk among those with a thrombotic event was 25% higher than those without one.

Lowering the risk of stroke and heart attack is already one of the main goals of managing polycythemia and essential thrombocythemia. But the findings by Pemmaraju and his colleagues highlight just how important it is. They note that in their study, high cholesterol was a common comorbidity among people with polycythemia vera and essential thrombocythemia, a finding that they say suggests that management of cholesterol and body weight could help reduce thrombotic risk of people with polycythemia vera and essential thrombocythemia and therefore their mortality risk.

The researchers conducted their retrospective, observational study using a Medicare fee-for-service claims database that included claims from 2010 to 2017. They sifted through those claims to identify just under 55,000 people with polycythemia vera and just 125,000 people with essential thrombocythemia.

Their next step was to use the claims to identify the proportion of those patients who had a thrombotic event,with strokes, heart attacks and TIAs being the most common of those events. They discovered that roughly 1 in 4 patients had a thrombotic event. More precisely, during a follow-up period of about three years (34.5 months), 14,334, or about 28%, of the people with polycythemia vera had a thrombotic event. During a shorter follow-up period of about two years (25.2 months), 30,478, or about 25%, of those with essential thrombocythemia had a thrombotic event.