title: The incidence of heparin-induced thrombocytopenia in patients treated with low molecular weight heparin for superficial vein thrombosis.
abstract: BACKGROUND
  The risk of heparin induced thrombocytopenia (HIT) associated with low molecular weight heparin (LMWH) for treatment of superficial vein thrombosis (SVT) is uncertain. As a result the necessity of platelet count monitoring is unclear in this setting.
  
  
  OBJECTIVE
  To assess the risk of HIT in outpatients treated with LMWH for SVT.
  
  
  METHODS
  In a prospective single centre study we included all symptomatic outpatients in whom a real-time B-mode and color Doppler ultrasonography examination revealed SVT without DVT. Patients treated with vitamin K antagonists or fondaparinux were excluded. Patients received full dose enoxaparin for 1week followed by half therapeutic dose for 3weeks or parnaparin 8500UI aXa for 10days followed by 6400UI aXa once daily for 20days. Platelet count was performed on the day of diagnosis (D0) and 7 (D7), and 14 (D14) days afterward. Primary outcomes were the rate of thromboembolic events and of HIT during a 3-month follow-up.
  
  
  RESULTS
  678 outpatients (age: 64.7±16.2years, male: 42.0%) were evaluated. During follow-up, 7 venous thrombo-embolic events were recorded (1.03% CI 95%: 0.50-2.11%), while no major bleeding was observed (0.0% CI 95%: 0.0-0.56%). Platelet count was 255±93×10(9)/L at D0, 245±93×10(9)/L at D7 (p=0.204 vs. D0) and 261±116×10(9)/L at D14 (p=0.405 vs. D0). No fall in platelet count>50% and no case of HIT were recorded (HR 0.0% CI 95%: 0-0.56%).
  
  
  CONCLUSIONS
  A 4-week LMWH treatment for SVT is associated with an incidence of HIT lower than 0.6% and platelet count monitoring may be omitted in this setting.
authors.affiliation: Department of Angiology and Blood Coagulation, S. Orsola-Malpighi University Hospital, 40138 Bologna, Italy. Electronic address: michelangelo.sartori@aosp.bo.it.
authors.forename: Michelangelo
authors.initials: M
authors.lastname: Sartori
authors.affiliation: Department of Angiology and Blood Coagulation, S. Orsola-Malpighi University Hospital, 40138 Bologna, Italy.
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Favaretto
authors.affiliation: Department of Angiology and Blood Coagulation, S. Orsola-Malpighi University Hospital, 40138 Bologna, Italy.
authors.forename: Ludovica
authors.initials: L
authors.lastname: Migliaccio
authors.affiliation: Department of Angiology and Blood Coagulation, S. Orsola-Malpighi University Hospital, 40138 Bologna, Italy.
authors.forename: Giuliana
authors.initials: G
authors.lastname: Guazzaloca
authors.affiliation: Department of Angiology and Blood Coagulation, S. Orsola-Malpighi University Hospital, 40138 Bologna, Italy.
authors.forename: Cristina
authors.initials: C
authors.lastname: Legnani
authors.affiliation: Department of Angiology and Blood Coagulation, S. Orsola-Malpighi University Hospital, 40138 Bologna, Italy.
authors.forename: Gualtiero
authors.initials: G
authors.lastname: Palareti
authors.affiliation: Department of Angiology and Blood Coagulation, S. Orsola-Malpighi University Hospital, 40138 Bologna, Italy.
authors.forename: Benilde
authors.initials: B
authors.lastname: Cosmi
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000009:adverse effects* / Q000627:therapeutic use; D005260:Female; D006495:Heparin, Low-Molecular-Weight / Q000009:adverse effects* / Q000627:therapeutic use; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D010976:Platelet Count; D011446:Prospective Studies; D013921:Thrombocytopenia / Q000139:chemically induced* / Q000453:epidemiology; D020246:Venous Thrombosis / Q000188:drug therapy*
chemical_list: D000925:Anticoagulants; D006495:Heparin, Low-Molecular-Weight
keywords: Heparin treatment; Heparin-induced thrombocytopenia; Low molecular weight heparin; Superficial vein thrombosis