title: Thrombocytopenia in the critically ill: prevalence, incidence, risk factors, and clinical outcomes.
abstract: OBJECTIVE
  The aim of this cohort study was to describe the prevalence, incidence, and risk factors for thrombocytopenia in the intensive care unit (ICU) and to evaluate the impact of thrombocytopenia on mortality with further comparisons amongst major diagnostic categories.
  
  
  METHODS
  Patients admitted to the ICU from 1997-2011 for cardiac, medical, surgical, and trauma conditions were included. The presence of a platelet count < 100 × 10(9)·L(-1) on admission day or its appearance during ICU stay were considered as prevalent and incident thrombocytopenia, respectively. Risk factors for thrombocytopenia and the influence of thrombocytopenia on mortality were also analyzed.
  
  
  RESULTS
  This study included 20,696 patients. Prevalent and incident thrombocytopenia occurred in 13.3% and 7.8% of patients, respectively, with associated mortality rates of 14.3% and 24.7%, respectively, compared with 10.2% in the group with normal platelet count (P < 0.001). After adjustments, thrombocytopenia remained associated with an increased risk of mortality (odds ratio 1.25; 95% confidence interval 1.20 to 1.31; P < 0.001). The greatest impact of thrombocytopenia on mortality was observed in the cancer, respiratory, digestive, genitourinary, and infectious diagnostic categories. Independent risk factors included age, female sex, admission platelet counts and hemoglobin, mechanical ventilation, days of hospitalization prior to ICU admission, liver cirrhosis, hypersplenism, coronary bypass grafting, intra-aortic balloon pump placement, acute hepatitis, septic shock, and pulmonary embolism or deep vein thrombosis.
  
  
  CONCLUSIONS
  Thrombocytopenia in the ICU is associated with an independent risk of mortality that varies greatly depending on diagnostic admission category.
authors.affiliation: Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Sherbrooke, QC, Canada. david.williamson@umontreal.ca
authors.forename: David R
authors.initials: DR
authors.lastname: Williamson
authors.forename: Olivier
authors.initials: O
authors.lastname: Lesur
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Tétrault
authors.forename: Vincent
authors.initials: V
authors.lastname: Nault
authors.forename: Danielle
authors.initials: D
authors.lastname: Pilon
mesh_terms: D000368:Aged; D001803:Blood Transfusion / Q000706:statistics & numerical data; D002318:Cardiovascular Diseases / Q000453:epidemiology; D015331:Cohort Studies; D003141:Communicable Diseases / Q000453:epidemiology; D001026:Coronary Artery Bypass / Q000706:statistics & numerical data; D003422:Critical Care / Q000706:statistics & numerical data; D016638:Critical Illness; D005112:Extracorporeal Circulation / Q000706:statistics & numerical data; D005260:Female; D006471:Gastrointestinal Hemorrhage / Q000453:epidemiology; D006349:Heart Valve Diseases / Q000453:epidemiology; D006402:Hematologic Diseases / Q000453:epidemiology; D006470:Hemorrhage / Q000453:epidemiology; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D015994:Incidence; D007902:Length of Stay / Q000706:statistics & numerical data; D008103:Liver Cirrhosis / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011792:Quebec / Q000453:epidemiology; D012121:Respiration, Artificial / Q000706:statistics & numerical data; D012189:Retrospective Studies; D012307:Risk Factors; D013921:Thrombocytopenia / Q000453:epidemiology* / Q000401:mortality; D016896:Treatment Outcome; D014652:Vascular Diseases / Q000453:epidemiology