High rate of abnormal blood values and vascular complications before diagnosis of myeloproliferative neoplasms.

Background: Vascular complications occurring before the diagnosis of myeloproliferative neoplasms (MPN) in 612 patients from four centers in Sweden, Denmark and France were retrospectively studied.

Results: Vascular complications were observed in 151 (25%) of the 612 patients. Of these, 66% occurred during the two years preceding diagnosis. The majority of events were thromboembolic (95%), and included myocardial infarction (n=46), ischemic stroke (n=43), transient ischemic attack (TIA) (n=22), deep vein thrombosis/pulmonary embolism (n=19), splanchnic vein thrombosis (n=7), and peripheral embolism (n=7). Bleeding was observed in only 7 (5%) of the 151 patients with vascular events (3 with intracranial bleeding, 2 with epistaxis and 2 with gastrointestinal bleeding). Full blood counts obtained at least 3 months prior to the MPN diagnosis showed that 269 (44%) had abnormal blood values, fulfilling the diagnostic criteria for MPN. During the time from the abnormal blood test to the diagnosis of MPN, 50 patients suffered from a vascular complication.

Conclusion: We therefore conclude that a large proportion of MPN patients suffer severe thromboembolic complications prior to diagnosis. If MPN were diagnosed earlier, a large proportion of these events might be prevented. An MPN should always be suspected and ruled out in patients with unexplained elevated hematocrit, leukocyte and/or platelet counts.