Clinical question: What are the risks for arterial and venous thrombosis in patients with myeloproliferative neoplasms (MPNs)?
Background: Myeloproliferative neoplasms include polycythemia vera, essential thrombocythemia, and primary myelofibrosis. Prior studies have investigated the incidence of arterial and venous thrombosis in patients with myeloproliferative neoplasms, but the actual magnitude of thrombosis risk relative to the general population is unknown.
Study design: Retrospective matched-cohort study.
Setting: Sweden, using the Swedish Inpatient and Cancer Registers.
Synopsis: Using data from 1987 to 2009, 9,429 patients with MPNs were compared with 35,820 control participants to determine hazard ratios for arterial thrombosis, venous thrombosis, and any thrombosis. The highest hazard ratios were seen within 3 months of MPN diagnosis, with hazard ratios of 4.0 (95% confidence interval, 3.6-4.4) for any thrombosis, 3.0 (95% CI, 2.7-3.4) for arterial thrombosis, and 9.7 (95% CI, 7.8-12.0) for venous thrombosis. Risk decreased but remained significantly elevated through follow-up out to 20 years after diagnosis. This decrease was thought to be caused by effective thromboprophylactic and cytoreductive treatment of the MPN.
This study demonstrates significantly elevated risk for thrombosis in patients with MPNs, highest shortly after diagnosis. It suggests the importance of timely diagnosis and treatment of MPNs to decrease early thrombosis risk.
Bottom line: Patients with MPNs have increased rates of arterial and venous thrombosis, with the highest rates within 3 months of diagnosis.
Citation: Hultcrantz M et al. Risk for arterial and venous thrombosis in patients with myeloproliferative neoplasms. Ann Intern Med. 2018 Mar 6;168(5):317-25.
Dr. Komsoukaniants is a hospitalist at UC San Diego Health and an assistant clinical professor at the University of California, San Diego.
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