title: Influence of platelet and white blood cell counts on major thrombosis - analysis from a patient registry in essential thrombocythemia.
abstract: OBJECTIVE
  Although guidelines recommend normalization of platelet counts as an appropriate endpoint for treatment in high-risk essential thrombocythemia (ET), retrospective studies could not prove a correlation of diagnostic platelet counts with an increased thrombotic rate. There is, however, an increasing evidence that leukocytosis is an important risk factor for arterial thrombosis in myeloproliferative neoplasms.
  
  
  METHODS
  This study considers the Austrian cohort of a European registry regarding the platelet-lowering therapeutic anagrelide. Influence of platelet and white blood cell (WBC) counts on thrombotic risk was assessed.
  
  
  RESULTS
  Using the calculated cutoffs of 574.5 G/L for platelets and 8.48 G/L for WBC counts, respectively, the Cox regression analysis revealed a clear influence of elevated platelets (P = 0.008) and WBC counts (P = 0.011) on the occurrence of major thrombotic events. The time to a major thrombotic event was shortest (P < 0.001) and the frequency related to 100 patient-years was highest (P = <0.001) when both platelet and WBC counts ranged above the calculated cutoffs.
  
  
  CONCLUSIONS
  Our data add evidence to the impact of platelet and WBC counts on thrombosis in ET. We suspect a particular interaction between platelets and WBC which might be based on a biological interplay depending on particular cell counts.
authors.affiliation: Division of Hematology and Blood Coagulation, Department of Internal Medicine I, Medical University of Vienna, Vienna, Austria.|Department of Internal Medicine I, Elisabethinen Hospital Linz, Linz, Austria.
authors.forename: Veronika
authors.initials: V
authors.lastname: Buxhofer-Ausch
authors.affiliation: Division of Hematology and Oncology, Innsbruck Medical University, Innsbruck, Austria.
authors.forename: Michael
authors.initials: M
authors.lastname: Steurer
authors.affiliation: Department of Hematology, Medical University of Graz, Graz, Austria.
authors.forename: Siegfried
authors.initials: S
authors.lastname: Sormann
authors.affiliation: Department of Internal Medicine 3, Hanusch Hospital, Vienna, Austria.
authors.forename: Ernst
authors.initials: E
authors.lastname: Schloegl
authors.affiliation: Department of Applied Systems Research and Statistics, Johannes Kepler University, Linz, Austria.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Schimetta
authors.affiliation: Division of Hematology and Blood Coagulation, Department of Internal Medicine I, Medical University of Vienna, Vienna, Austria.
authors.forename: Bettina
authors.initials: B
authors.lastname: Gisslinger
authors.affiliation: Department of Internal Medicine 2, Donauspital, Vienna, Austria.
authors.forename: Reinhard
authors.initials: R
authors.lastname: Ruckser
authors.affiliation: Division of Hematology and Oncology, Innsbruck Medical University, Innsbruck, Austria.
authors.forename: Günther
authors.initials: G
authors.lastname: Gastl
authors.affiliation: Division of Hematology and Blood Coagulation, Department of Internal Medicine I, Medical University of Vienna, Vienna, Austria.
authors.forename: Heinz
authors.initials: H
authors.lastname: Gisslinger
mesh_terms: D000368:Aged; D001792:Blood Platelets; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D053208:Kaplan-Meier Estimate; D007958:Leukocyte Count; D008297:Male; D008875:Middle Aged; D010975:Platelet Aggregation Inhibitors / Q000627:therapeutic use; D011379:Prognosis; D016016:Proportional Hazards Models; D011799:Quinazolines / Q000627:therapeutic use; D012042:Registries; D018570:Risk Assessment; D013920:Thrombocythemia, Essential / Q000097:blood* / Q000150:complications* / Q000175:diagnosis / Q000453:epidemiology; D013927:Thrombosis / Q000097:blood* / Q000188:drug therapy / Q000453:epidemiology / Q000209:etiology*
chemical_list: D010975:Platelet Aggregation Inhibitors; D011799:Quinazolines; C021139:anagrelide
keywords: essential thrombocythemia; platelet count; thrombosis risk; white blood cell count