title: Mean platelet volume is a risk factor for venous thromboembolism: the Tromsø Study, Tromsø, Norway.
abstract: BACKGROUND
  Platelet size, measured as mean platelet volume (MPV), is associated with platelet reactivity. MPV is increased in acute myocardial infarction, and has been identified as an independent risk factor for future myocardial infarction and stroke.
  
  
  OBJECTIVE
  The purpose of the study was to determine the impact of platelet count and MPV on the incidence of venous thromboembolism (VTE) in a prospective, population-based study.
  
  
  METHODS
  Platelet count, MPV and baseline characteristics were registered in 25 923 subjects aged 25-96 years who participated in the Tromsø Study in 1994-1995. Incident VTE events were registered to the end of follow-up (1 September 2007).
  
  
  RESULTS
  There were 445 validated incident VTE events (1.6 per 1000 person-years), of which 186 (42%) were unprovoked, during a mean of 10.8 years of follow-up. Subjects with MPV >or= 9.5 fL had a 1.3-fold [95% confidence interval (CI) 1.0-1.7] higher risk of total VTE and a 1.5-fold (95% CI 1.1-2.3) higher risk of unprovoked VTE than subjects with MPV < 8.5 fL in analyses adjusted for age, sex, smoking, body mass index, and platelet count. Increasing MPV was associated with increased risk of total VTE (P for trend = 0.09) and unprovoked VTE (P for trend = 0.03) in analyses adjusted for age and sex. There was no significant association between increasing platelet count and risk of VTE.
  
  
  CONCLUSIONS
  An increasing MPV was identified as a predictor for VTE, in particular VTE of unprovoked origin. The present findings support the concept that platelet reactivity is important in the pathogenesis of VTE.
authors.affiliation: Center for Atherothrombotic Research in Tromsø (CART), Institute of Clinical Medicine, University of Tromsø, Tromsø, Norway. sigrid.brakkan@uit.no
authors.forename: S K
authors.initials: SK
authors.lastname: Braekkan
authors.forename: E B
authors.initials: EB
authors.lastname: Mathiesen
authors.forename: I
authors.initials: I
authors.lastname: Njølstad
authors.forename: T
authors.initials: T
authors.lastname: Wilsgaard
authors.forename: J
authors.initials: J
authors.lastname: Størmer
authors.forename: J B
authors.initials: JB
authors.lastname: Hansen
mesh_terms: D000328:Adult; D001792:Blood Platelets / Q000473:pathology*; D048429:Cell Size; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009664:Norway / Q000453:epidemiology; D010976:Platelet Count; D010979:Platelet Function Tests; D011159:Population Surveillance; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models; D011446:Prospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D013997:Time Factors; D054556:Venous Thromboembolism / Q000097:blood / Q000453:epidemiology / Q000209:etiology*