title: Safety and efficacy of starting warfarin after two consecutive platelet count rises in heparin-induced thrombocytopenia.
abstract: BACKGROUND
  Current guidelines on the treatment of heparin-induced thrombocytopenia (HIT) recommend warfarin initiation when platelet levels recover to 150×10(9)/L or more. However, many patients may not achieve this platelet level or may have slow platelet recovery. The aim of this study is to determine if initiating warfarin when platelets start trending upward instead of at a specific level is safe and effective in patients diagnosed with HIT.
  
  
  METHODS
  Two groups of patients diagnosed and treated for HIT in a tertiary care hospital were assessed for HIT-related outcomes: 28 patients had warfarin initiated after platelets recovered to 150×10(9)/L or more and 30 patients had warfarin initiated prior to platelet recovery.
  
  
  RESULTS
  There was no significant difference between the rate of thrombosis, venous limb gangrene, or limb amputation. Three patients died during the data collection period, all deemed to be unrelated to HIT by independent investigators. The average hospital length of stay was 22.2±12.7days and 38.8±19.1days for patients who started warfarin at platelets less than 150×10(9)/L and platelets greater than or equal to 150×10(9)/L respectively (P=0.0002).
  
  
  CONCLUSIONS
  The data suggests that the absolute platelet level at which warfarin is initiated does not affect the rate of thrombosis or mortality but may shorten overall hospital length of stay and associated costs. Therefore, it may be more important to observe an upward trend in platelets rather than striving to achieve an absolute platelet level before starting warfarin in patients with HIT.
authors.affiliation: Department of Pharmacy, University of California Davis Medical Center, United States.
authors.forename: Lydia D
authors.initials: LD
authors.lastname: Chen
authors.affiliation: Department of Pharmacy, University of California Davis Medical Center, United States.
authors.forename: A Josh
authors.initials: AJ
authors.lastname: Roberts
authors.affiliation: Department of Pharmacy, University of California Davis Medical Center, United States. Electronic address: wedager@ucdavis.edu.
authors.forename: William E
authors.initials: WE
authors.lastname: Dager
mesh_terms: D000328:Adult; D000368:Aged; D000925:Anticoagulants / Q000627:therapeutic use*; D005260:Female; D005343:Fibrinolytic Agents / Q000009:adverse effects*; D006493:Heparin / Q000009:adverse effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010976:Platelet Count; D012189:Retrospective Studies; D013921:Thrombocytopenia / Q000139:chemically induced* / Q000150:complications; D013927:Thrombosis / Q000150:complications / Q000188:drug therapy*; D014859:Warfarin / Q000627:therapeutic use*
chemical_list: D000925:Anticoagulants; D005343:Fibrinolytic Agents; D014859:Warfarin; D006493:Heparin