title: Home monitoring of warfarin therapy in children with a whole blood prothrombin time monitor.
abstract: We prospectively evaluated a capillary whole blood prothrombin time (PT) monitor (Biotrack, Ciba Corning) in an outpatient pediatric anticoagulation clinic (40 clinic patients) and in age-matched healthy subjects (30 control subjects). Subsequently, 23 children requiring warfarin therapy were placed on a home program (home patients) using the PT monitor; their parents were trained and the results followed by clinic staff. The PT results were reported as internationalized normalized ratios (INRs). The laboratory and PT-monitor INR values were similar for the clinic patients and the control subjects (y = 0.76x + 0.38; r = 0.93; p < 0.001). The accuracy of the PT monitor (the difference between INR values and the laboratory INR) was best at an INR of 2.5 to 3.5; 90% of paired INR values were within 0.8 INR units. The average duration of monitoring for home patients was 13 months (range, 2 to 60 months). They had an average of 3 dose measurements (range, 1 to 11 measurements) and 1.8 dose changes (range, 0.6 to 4.5 changes) per month. Of the 599 measurements, 63% were within the therapeutic range, similar to those for clinic patients; the dose requirements were also similar. There was 1 significant bleeding event, a subdural hematoma in a patient with an INR of 4.1, and 1 catheter-related thrombotic event with an INR of 1.2; both children recovered. Of the 23 families, one discontinued home monitoring because of parental discomfort, 2 children died of their primary disease, 6 completed warfarin therapy, and 14 remain on the home program. We conclude that the whole blood PT/INR monitor is safe and offers practical advantages to children requiring anticoagulation.
authors.affiliation: Children's Hospital at Chedoke-McMaster, Hamilton, Ontario, Canada.
authors.forename: P
authors.initials: P
authors.lastname: Massicotte
authors.forename: V
authors.initials: V
authors.lastname: Marzinotto
authors.forename: P
authors.initials: P
authors.lastname: Vegh
authors.forename: M
authors.initials: M
authors.lastname: Adams
authors.forename: M
authors.initials: M
authors.lastname: Andrew
mesh_terms: D000293:Adolescent; D002675:Child, Preschool; D016903:Drug Monitoring / Q000295:instrumentation / Q000379:methods* / Q000706:statistics & numerical data; D005069:Evaluation Studies as Topic; D005260:Female; D006701:Home Nursing / Q000379:methods* / Q000706:statistics & numerical data; D006801:Humans; D007223:Infant; D016014:Linear Models; D008297:Male; D010353:Patient Education as Topic; D011446:Prospective Studies; D011517:Prothrombin Time; D014859:Warfarin / Q000008:administration & dosage*
chemical_list: D014859:Warfarin