Prediction of thrombotic and hemorrhagic events during polycythemia vera or essential thrombocythemia based on leukocyte burden.
BACKGROUND
Evidences suggest an association between leukocytosis and thrombotic or hemorrhagic complication in polycythemia vera (PV) and essential thrombocythemia (ET), but clinical implication is not well known.


OBJECTIVE
To evaluate whether leukocyte burden during follow-up is related to thrombotic or hemorrhagic events in PV and ET.


METHODS
We retrospectively analyzed patients with PV or ET treated at Seoul National University Bundang Hospital, Korea. Time-weighted averages of leukocytes during the follow-up period were defined as leukocyte burden and were calculated for each patient and compared between patient subgroups. In each patient with events, leukocyte burden for the 3-month period before the event was compared with that for the entire follow-up period.


RESULTS
In 102 patients with PV or ET, 35 events (16 thrombotic, 19 hemorrhagic) occurred in 29 patients (median follow-up, 54months). Leukocyte burden were significantly higher in patients with events than in event-free patients (12,015×10(3) /μL vs. 9,567×10(3)/μL, P=0.003). The difference was more prominent in ET patients than in PV patients, and in patients with hemorrhagic events than in those with thrombotic events. In patients with events, the leukocyte burden in the pre-event period was higher than in the entire follow-up period (16,767×10(3)/μL vs. 12,015×10(3)/μL, P=0.002). In all patients, leukocyte burden during entire follow-up period of 11,000×10(3)/μL or higher was an independent risk factor for vascular events.


CONCLUSIONS
In PV or ET patients, leukocyte burden during disease course is related to increased incidence of thrombotic or hemorrhagic events.
Department of Internal Medicine, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam, Republic of Korea.
Yoojoo
Y
Lim
Department of Internal Medicine, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam, Republic of Korea.
Jeong-Ok
JO
Lee
Department of Internal Medicine, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam, Republic of Korea.
Se Hyun
SH
Kim
Department of Internal Medicine, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam, Republic of Korea.
Jin Won
JW
Kim
Department of Internal Medicine, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam, Republic of Korea.
Yu Jung
YJ
Kim
Department of Internal Medicine, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam, Republic of Korea.
Keun-Wook
KW
Lee
Department of Internal Medicine, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam, Republic of Korea.
Jong Seok
JS
Lee
Department of Internal Medicine, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam, Republic of Korea. Electronic address: smbang7@snu.ac.kr.
Soo-Mee
SM
Bang
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019540:Area Under Curve; D001772:Blood Cell Count; D015897:Comorbidity; D016208:Databases, Factual; D005260:Female; D005500:Follow-Up Studies; D006470:Hemorrhage / Q000453:epidemiology / Q000209:etiology*; D006474:Hemorrhagic Disorders / Q000097:blood / Q000209:etiology; D006801:Humans; D006918:Hydroxyurea / Q000009:adverse effects / Q000627:therapeutic use; D007958:Leukocyte Count; D008297:Male; D008875:Middle Aged; D018962:Phlebotomy; D010975:Platelet Aggregation Inhibitors / Q000009:adverse effects / Q000627:therapeutic use; D011087:Polycythemia Vera / Q000097:blood / Q000150:complications* / Q000188:drug therapy; D011379:Prognosis; D011799:Quinazolines / Q000009:adverse effects / Q000627:therapeutic use; D012189:Retrospective Studies; D012307:Risk Factors; D013920:Thrombocythemia, Essential / Q000097:blood / Q000150:complications* / Q000188:drug therapy; D019851:Thrombophilia / Q000097:blood / Q000209:etiology; D013927:Thrombosis / Q000453:epidemiology / Q000209:etiology* / Q000517:prevention & control; D055815:Young Adult
D010975:Platelet Aggregation Inhibitors; D011799:Quinazolines; C021139:anagrelide; D006918:Hydroxyurea
Essential thrombocythemia; Hemorrhage; Polycythemia vera; Predictor; Thrombosis; Time-weighted averages