HOME MONITORING OF WARFARIN THERAPY IN CHILDREN WITH A WHOLE-BLOOD PROTHROMBIN TIME MONITOR

We prospectively evaluated a capillary whole blood prothrombin time (P T) monitor (Biotrack, Ciba Coming) in an outpatient pediatric anticoag ulation clinic (40 clinic patients) and in age-matched healthy subject s (30 control subjects). Subsequently, 23 children requiring warfarin therapy were placed on a home program (home patients) using the PT mon itor; their parents were trained and the results followed by clinic st aff, The PT results were reported as internationalized normalized rati os (INRs). The laboratory and PT-monitor INR values were similar for t he clinic patients and the control subjects (y = 0.76x + 0.38; r = 0.9 3; 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; 9 0% of paired INR values were within 0.8 INR units, The average duratio n of monitoring for home patients was 13 months (range, 2 to 60 months ), They had an average of 3 dose measurements (range, I to 11 measurem ents) and 1.8 dose changes (range, 0.6 to 4.5 changes) per month, Of t he 599 measurements, 63% were within the therapeutic range, similar to those for clinic patients; the dose requirements were also similar, T here was 1 significant bleeding event, a subdural hematoma in a patien t 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 discontin ued 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 anticoagula tion.