Patients With Myeloproliferative Neoplasms May Have Increased Thrombosis Risk

For years, many health care professionals noticed that patients with myeloproliferative neoplasms (MPNs) tend to experience thrombosis more than the average person. Now, a recent population-based study conducted in Sweden confirmed their suspicions.

“The magnitude of the risk for thrombosis in patients with MPNs in relation to the general population is largely unknown,” the researchers wrote in their study, which was published in the Annals of Internal Medicine.

“Therefore, we conducted a comprehensive population-based study to assess the relative risk for thrombosis in patients with MPNs compared with matched control participants overall and in relation to clinical features and follow-up time.”

Using the Swedish Cancer Register, the researchers examined 9,429 patients with MPNs and 35,820 matched control participants. Patients and controls were then followed until their first thrombotic event — meaning they had blood clotting in their circulatory system. Hazard ratios (HRs) were then calculated to see the degree of correlation.

“The rate of thrombosis was significantly higher in patients with MPNs, and the highest HR was observed shortly after MPN diagnosis,” the authors wrote.

Researchers observed a nearly 10-fold increase in venous thrombosis (blood clots in the vein) within three months of patients being diagnosed with an MPN. This correlation did decrease over time, but researchers saw an elevated number of thrombotic events at one and five years post-diagnosis.

Similarly, the HRs for pulmonary embolism and deep venous thrombosis were also elevated at diagnosis and then decreased as time went on.

The study was conducted between 1987 and 2009, so the researchers noted that the percentage of patients developing thrombosis did decrease over the years, pointing toward improved treatment.

“The excess rate of venous thrombosis decreased during more recent calendar periods, implying a positive effect of improved treatment strategies,” they wrote. “In addition, absolute risk for arterial thrombosis has decreased overall in patients with MPNs and the general population in recent decades.”

The researchers also mentioned that newer, commonly used drugs to treat MPNs, such as Jakafi (ruxolitinib) and interferon, may also decrease a patient’s risk of thrombosis.

However, there is still work to be done. Further analysis of subgroups — particularly younger patients with MPNs – is needed, as well as what other risk factors may be.

“Nevertheless, there are more complex mechanisms than age and prior thrombosis to consider when assessing thrombotic risk in patients with MPNs.”