title: Coated platelets and severe haemophilia A bleeding phenotype: Is there a connection?
abstract: BACKGROUND
  Coated platelets are a subpopulation of platelets that possess highly prothrombotic properties. Previous observational data suggest that bleeding phenotype in severe haemophilia A is associated with coated platelet levels. Haemophilia A patients with higher coated platelet levels may have a mild bleeding phenotype; those with lower levels may have a more severe bleeding phenotype.
  
  
  OBJECTIVE
  The aim of the study was to test the hypothesis that coated platelet levels are correlated with clinical bleeding phenotype.
  
  
  METHODS
  This cross-sectional, observational study enrolled 20 severe haemophilia A patients, including 15 with severe and five with a mild bleeding phenotype, and a control group of 12 healthy volunteers. The haemophilia bleeding phenotype was determined by the patient's medical history and haemophilia treatment centre records. Blood was obtained from each patient by venipuncture and platelets were analysed by flow cytometry.
  
  
  RESULTS
  Patients categorized as having a severe bleeding phenotype experienced a median eight bleeds per year compared to one bleed annually in the mild bleeding phenotype group. Both groups had similar total platelet counts and fibrinogen levels. There was no difference in coated platelet percentage between severe and mild bleeding phenotype (17 and 16% respectively), however, both groups had significantly lower % coated platelets compared to controls (44%, P < 0.0001).
  
  
  CONCLUSIONS
  Coated platelet levels were not associated with bleeding phenotype in this study; however, these data may suggest coated platelet levels are lower in haemophilia patients relative to healthy volunteers.
authors.affiliation: Department of Pediatric Hematology/Oncology, Children's Hospital of Richmond and Virginia Commonwealth University Health System, Richmond, VA, USA.|Coagulation Advancement Laboratory, Department of Pharmacotherapy & Outcomes Science, Virginia Commonwealth University, Richmond, VA, USA.
authors.forename: K K
authors.initials: KK
authors.lastname: Lastrapes
authors.affiliation: Coagulation Advancement Laboratory, Department of Pharmacotherapy & Outcomes Science, Virginia Commonwealth University, Richmond, VA, USA.|Department of Clinical Pharmacy, Faculty of Pharmacy, Cairo University, Giza, Egypt.
authors.forename: B M
authors.initials: BM
authors.lastname: Mohammed
authors.affiliation: Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, NC, USA.
authors.forename: M A
authors.initials: MA
authors.lastname: Mazepa
authors.affiliation: Coagulation Advancement Laboratory, Department of Pharmacotherapy & Outcomes Science, Virginia Commonwealth University, Richmond, VA, USA.
authors.forename: E J
authors.initials: EJ
authors.lastname: Martin
authors.affiliation: Division of Hematology/Oncology, Virginia Commonwealth University, Richmond, VA, USA.
authors.forename: J C
authors.initials: JC
authors.lastname: Barrett
authors.affiliation: Department of Pediatric Hematology/Oncology, Children's Hospital of Richmond and Virginia Commonwealth University Health System, Richmond, VA, USA.
authors.forename: G V
authors.initials: GV
authors.lastname: Massey
authors.affiliation: Division of Hematology/Oncology, Virginia Commonwealth University, Richmond, VA, USA.
authors.forename: J G
authors.initials: JG
authors.lastname: Kuhn
authors.affiliation: Division of Hematology/Oncology, Virginia Commonwealth University, Richmond, VA, USA.
authors.forename: M E
authors.initials: ME
authors.lastname: Nolte
authors.affiliation: Department of Pathology, Duke University and Durham Veterans Affairs Medical Centers, Durham, NC, USA.|Department of Medicine, University of North Carolina, Chapel Hill, NC, USA.
authors.forename: M
authors.initials: M
authors.lastname: Hoffman
authors.affiliation: Department of Medicine, University of North Carolina, Chapel Hill, NC, USA.
authors.forename: D M
authors.initials: DM
authors.lastname: Monroe
authors.affiliation: Coagulation Advancement Laboratory, Department of Pharmacotherapy & Outcomes Science, Virginia Commonwealth University, Richmond, VA, USA.
authors.forename: D F
authors.initials: DF
authors.lastname: Brophy
mesh_terms: D000293:Adolescent; D000328:Adult; D001792:Blood Platelets / Q000502:physiology*; D002648:Child; D006467:Hemophilia A / Q000150:complications* / Q000503:physiopathology*; D006470:Hemorrhage / Q000150:complications*; D006801:Humans; D010641:Phenotype; D013927:Thrombosis / Q000150:complications; D055815:Young Adult
keywords: bleeding; haemophilia; patient monitoring; phenotype; platelets