title: Monitoring aspirin therapy in children after interventional cardiac catheterization: laboratory measures, dose response, and clinical outcomes.
abstract: Very few studies have investigated dose response of aspirin and agreement of different platelet function assays in children. One hundred five children were studied at baseline and after interventional cardiac catheterization during aspirin treatment and, in cases of aspirin resistance (AR), after dose increase. Results from arachidonate-induced aggregation (AA) were compared with aggregation induced by ADP, PFA-100 closure times (CTs), urinary 11-dehydro-thromboxane B2 (urinary 11-dhTxB2) levels, and Impact-R % surface coverage. Aspirin at 2-5 mg/kg/day inhibited platelet function in a large majority. While 19 % showed bruising and mild epistaxis, no thrombotic complications were recorded. AR was detected by AA in seven children (6.7 %). After dose increase, the majority showed inhibition by aspirin. Infants had higher urinary 11-dhTxB2 baseline levels; this assay showed some correlation with AA. Both assays manifested high sensitivity and specificity for aspirin while inferior results were found for the other assays. With the PFA-100, 15.2 % of patients were found to have AR, but this corresponded to AR by AA in only one of seven children.
  
  
  CONCLUSIONS
  While there was poor agreement among assays, AA and urinary 11-dhTxB2 show good specificity for the monitoring of aspirin therapy in children. Aspirin at 2-5 mg/kg inhibits platelet function; AR in children is rare and can be overcome by dose increase.
authors.affiliation: Division of Haematology and Children's Research Centre, University Children's Hospital, Steinwiesstrasse 75, 8032, Zurich, Switzerland, markus.schmugge@kispi.uzh.ch.
authors.forename: Markus
authors.initials: M
authors.lastname: Schmugge
authors.forename: Oliver
authors.initials: O
authors.lastname: Speer
authors.forename: Sabine
authors.initials: S
authors.lastname: Kroiss
authors.forename: Walter
authors.initials: W
authors.lastname: Knirsch
authors.forename: Oliver
authors.initials: O
authors.lastname: Kretschmar
authors.forename: Margaret L
authors.initials: ML
authors.lastname: Rand
authors.forename: Manuela
authors.initials: M
authors.lastname: Albisetti
mesh_terms: D000293:Adolescent; D001095:Arachidonic Acids / Q000494:pharmacology; D001241:Aspirin / Q000008:administration & dosage*; D006328:Cardiac Catheterization; D002648:Child; D002675:Child, Preschool; D004305:Dose-Response Relationship, Drug; D016903:Drug Monitoring; D004351:Drug Resistance; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D010974:Platelet Aggregation / Q000187:drug effects; D010975:Platelet Aggregation Inhibitors / Q000008:administration & dosage*; D011446:Prospective Studies; D013929:Thromboxane B2 / Q000031:analogs & derivatives / Q000652:urine; D055815:Young Adult
chemical_list: D001095:Arachidonic Acids; D010975:Platelet Aggregation Inhibitors; D013929:Thromboxane B2; C049235:11-dehydro-thromboxane B2; D001241:Aspirin