title: Thrombocytopenia in critically ill patients receiving thromboprophylaxis: frequency, risk factors, and outcomes.
abstract: BACKGROUND
  Thrombocytopenia is the most common hemostatic disorder in critically ill patients. The objective of this study was to describe the incidence, risk factors, and outcomes of thrombocytopenia in patients admitted to medical-surgical ICUs.
  
  
  METHODS
  Three thousand seven hundred forty-six patients in 67 centers were enrolled in a randomized trial in which unfractionated heparin was compared with low-molecular-weight heparin (LMWH) for thromboprophylaxis. Patients who had baseline platelet counts < 75 × 10(9)/L or severe coagulopathy at screening were excluded. We analyzed the risk of developing mild (100-149 × 10(9)/L), moderate (50-99 × 10(9)/L), and severe (< 50 × 109/L) thrombocytopenia during an ICU stay. We also assessed independent and time-varying predictors of thrombocytopenia and the effect of thrombocytopenia on major bleeding, transfusions, and death.
  
  
  RESULTS
  The incidences of mild, moderate, and severe thrombocytopenia were 15.3%, 5.1%, and 1.6%, respectively. The predictors of each category of thrombocytopenia were APACHE (Acute Physiology and Chronic Health Evaluation) II score, use of inotropes or vasopressors, and renal replacement therapy. The risk of moderate thrombocytopenia was lower in patients who received LMWH thromboprophylaxis but higher in surgical patients and in patients who had liver disease. Each category of thrombocytopenia was associated with subsequent bleeding and transfusions. Moderate and severe thrombocytopenia were associated with increased ICU and hospital mortality.
  
  
  CONCLUSIONS
  A high severity of illness, prior surgery, use of inotropes or vasopressors, renal replacement therapy, and liver dysfunction are associated with a higher risk of thrombocytopenia developing in the ICU, whereas LMWH thromboprophylaxis is associated with a lower risk. Patients who develop thrombocytopenia in the ICU are more likely to bleed, receive transfusions, and die.
authors.affiliation: Hôpital du Sacré-Coeur de Montréal, Montreal, QC, Canada; Department of Pharmacy, Université de Montréal, Montreal, QC, Canada. Electronic address: david.williamson@umontreal.ca.
authors.forename: David R
authors.initials: DR
authors.lastname: Williamson
authors.affiliation: Hôpital du Sacré-Coeur de Montréal, Montreal, QC, Canada; Department of Medicine, Université de Montréal, Montreal, QC, Canada.
authors.forename: Martin
authors.initials: M
authors.lastname: Albert
authors.affiliation: Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, ON, Canada.
authors.forename: Diane
authors.initials: D
authors.lastname: Heels-Ansdell
authors.affiliation: Canadian Blood Services, Ottawa, ON, Canada; Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, ON, Canada.
authors.forename: Donald M
authors.initials: DM
authors.lastname: Arnold
authors.affiliation: Centre de recherche du CHU de Québec and Université Laval, Montreal, QC, Canada.
authors.forename: François
authors.initials: F
authors.lastname: Lauzier
authors.affiliation: Cancercare Manitoba and University of Manitoba, Winnipeg, MB, Canada.
authors.forename: Ryan
authors.initials: R
authors.lastname: Zarychanski
authors.affiliation: Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, ON, Canada.
authors.forename: Mark
authors.initials: M
authors.lastname: Crowther
authors.affiliation: Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, ON, Canada; Department of Medicine, McMaster University, Hamilton, ON, Canada; Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON, Canada.
authors.forename: Theodore E
authors.initials: TE
authors.lastname: Warkentin
authors.affiliation: St.Paul's Hospital and University of British Columbia, Vancouver, BC, Canada.
authors.forename: Peter
authors.initials: P
authors.lastname: Dodek
authors.affiliation: Royal Melbourne Hospital, Melbourne, VIC, Australia.
authors.forename: John
authors.initials: J
authors.lastname: Cade
authors.affiliation: Centre Hospitalier Universitaire de Sherbrooke and Université de Sherbrooke, Sherbrooke, QC, Canada.
authors.forename: Olivier
authors.initials: O
authors.lastname: Lesur
authors.affiliation: Department of Medicine, McMaster University, Hamilton, ON, Canada.
authors.forename: Wendy
authors.initials: W
authors.lastname: Lim
authors.affiliation: Department of Medicine, University of Toronto, Toronto, ON, Canada; Sunnybrook Health Sciences Center, Toronto, ON, Canada.
authors.forename: Robert
authors.initials: R
authors.lastname: Fowler
authors.affiliation: Centre Hospitalier Universitaire de Sherbrooke and Université de Sherbrooke, Sherbrooke, QC, Canada.
authors.forename: Francois
authors.initials: F
authors.lastname: Lamontagne
authors.affiliation: Centre de recherche du CHU de Québec and Université Laval, Montreal, QC, Canada.
authors.forename: Stephan
authors.initials: S
authors.lastname: Langevin
authors.affiliation: Department of Medicine, McMaster University, Hamilton, ON, Canada.
authors.forename: Andreas
authors.initials: A
authors.lastname: Freitag
authors.affiliation: Kingston General Hospital and Queens University, Kingston, ON, Canada.
authors.forename: John
authors.initials: J
authors.lastname: Muscedere
authors.affiliation: Department of Medicine, University of Toronto, Toronto, ON, Canada; St. Michael's Hospital, Toronto, ON, Canada.
authors.forename: Jan O
authors.initials: JO
authors.lastname: Friedrich
authors.affiliation: Department of Medicine, University of Toronto, Toronto, ON, Canada; Sunnybrook Health Sciences Center, Toronto, ON, Canada.
authors.forename: William
authors.initials: W
authors.lastname: Geerts
authors.affiliation: Mount Sinai Hospital, Toronto, ON, Canada.
authors.forename: Lisa
authors.initials: L
authors.lastname: Burry
authors.affiliation: King Abdulaziz University, Jeddah, Saudi Arabia.
authors.forename: Jamal
authors.initials: J
authors.lastname: Alhashemi
authors.affiliation: Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, ON, Canada; Department of Medicine, McMaster University, Hamilton, ON, Canada.
authors.forename: Deborah
authors.initials: D
authors.lastname: Cook
mesh_terms: D000925:Anticoagulants / Q000627:therapeutic use*; D016638:Critical Illness; D005260:Female; D006493:Heparin / Q000627:therapeutic use*; D006495:Heparin, Low-Molecular-Weight / Q000627:therapeutic use*; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D016037:Single-Blind Method; D013921:Thrombocytopenia / Q000453:epidemiology*; D016896:Treatment Outcome
chemical_list: D000925:Anticoagulants; D006495:Heparin, Low-Molecular-Weight; D006493:Heparin