Increased risk of thrombosis in myeloproliferative neoplasms

(HealthDay)—Patients with myeloproliferative neoplasms (MPNs) have increased risk of arterial thrombosis and venous thrombosis across all age groups and MPN subtypes, according to a study published online Jan. 16 in the Annals of Internal Medicine.

Malin Hultcrantz, M.D., Ph.D., from Karolinska University Hospital and Karolinska Institutet in Stockholm, and colleagues examined the risk for arterial and venous thrombosis seen in patients with MPNs versus control participants in a population-based setting. Data were included for 9,429 patients with MPNs and 35,820 matched control participants in Sweden from 1987 to 2009, with follow-up to 2010.

The researchers found that, compared with control participants, for patients with MPNs, the hazard ratios for arterial thrombosis were 3.0, 2.0, and 1.5 at three months, one year, and five years, respectively. For venous thrombosis, the corresponding hazard ratios were 9.7, 4.7, and 3.2. Across all age groups, the rate was significantly increased and was similar for MPN subtypes. In patients with MPNs, the five-year cumulative incidence of thrombosis showed an initial rapid increase followed by a smaller increase during follow-up. During more recent calendar periods, the hazard ratio for venous thrombosis decreased.

"Patients with MPNs across all age groups have a significantly increased rate of arterial and venous thrombosis compared with matched control participants, with the highest rates at and shortly after diagnosis," the authors write.