DIOPATHIC thrombocytopenic purpura (ITP, also I known as primary immune thrombocytopenic purpura) is a hematologic disorder for which appropriate diagnostic and treatment strategies are uncertain. In 1994, the American Society of Hematology (ASH) established a panel to produce explicitly developed practice guidelines for the diagnosis and management of ITP. "Explicitly developed," evidencebased practice guidelines, which are being issued increasingly by medical specialty societies, combine a critical appraisal of scientific evidence with practice recommendations that state clearly to what extent the guidelines are based either on published scientific evidence or opinion (eg, clinical experience).I4 More details about the clinical practice guideline movement are provided elsewhere.'.'This report begins with a brief summary of the panel's recommendations, followed by a more detailed analysis of its methodology, the findings of the comprehensive literature review, and a full presentation of the recommendations. The report concludes with recommendations for future research. As explained later, the recommendations are based on the panel's opinion, derived from a systematic scoring methodology. (Only recommendations receiving scores of 1 .O to 3.0 or 7.0 to 9.0, as defined later in the text, are cited in this summary.) SUMMARY OF RECOMMENDATIONS Children Diagnosis

DIOPATHIC thrombocytopenic purpura (ITP, also I known as primary immune thrombocytopenic purpura) is a hematologic disorder for which appropriate diagnostic and treatment strategies are uncertain. In 1994, the American Society of Hematology (ASH) established a panel to produce explicitly developed practice guidelines for the diagnosis and management of ITP. "Explicitly developed," evidencebased practice guidelines, which are being issued increasingly by medical specialty societies, combine a critical appraisal of scientific evidence with practice recommendations that state clearly to what extent the guidelines are based either on published scientific evidence or opinion (eg, clinical experience).I4 More details about the clinical practice guideline movement are provided elsewhere.'.' This report begins with a brief summary of the panel's recommendations, followed by a more detailed analysis of its methodology, the findings of the comprehensive literature review, and a full presentation of the recommendations. The report concludes with recommendations for future research. As explained later, the recommendations are based on the panel's opinion, derived from a systematic scoring methodology. (Only recommendations receiving scores of 1 .O to 3.0 or 7.0 to 9.0, as defined later in the text, are cited in this summary.)

Summary. Background: Inhibitors are rare in boys with mild hemophilia A (MHA; factor (F)VIII:C >5%) but may arise following intense FVIII exposure, e.g. continuous infusion (CI). Objectives: To determine the impact of intense FVIII exposure in inhibitor formation in MHA at our institution and to compare this with previous reports. Patients and methods: We reviewed FVIII exposure and inhibitor development in boys (ages 0-18 years) with MHA followed at our institution from 1996 to 2001 and conducted a Medline search on the experience of inhibitor development following intensive/CI exposure to FVIII. Results: We identified 54 boys with MHA. Twenty-nine (54%) had been exposed to FVIII. Seven had received FVIII by CI. Four developedinhibitors;threehightiter(atages10 years,16 yearsand 17 years) and one low titer (at 1 month old). All four had received a CI of recombinant (r) FVIII of at least 6 days within 6 weeks of developing inhibitors. Baseline FVIII levels fell to <1% in all cases and the three with high-titer inhibitors developed severe bleeding. Immune tolerance therapy (ITT) was attempted in two boys and was successful in one. Our literature search identified 35 cases (only four children) with MHA developing inhibitors following intense FVIII exposure often in the context of surgery. Conclusions: The incidence of inhibitors in our MHA population was 7.4%. If expressed according to exposure the incidence was significantly higher: 14% (4/29) for any exposure to FVIII and 57% (4/7) for exposure by CI. A prospective study to address whether CI is associated with an increased incidence of inhibitor development in MHA is warranted.

Primary prophylaxis is the emerging standard treatment for boys with severe haemophilia. Tailored (escalating-dose) prophylaxis (EscDose), beginning at a low frequency and escalating with repeated bleeding may prevent arthropathy at a lower cost than standard prophylaxis (SP). From a societal perspective, we compared the incremental cost per joint-haemorrhage that is avoided and quality-adjusted-life-year (QALY) gained of SP and EscDose to on-demand (Demand) therapy in severe haemophilia A boys treated to age 6 using a decision analytic model. Costs included factor VIII (FVIII), professional visits and tests, central venous placement/complications, hospitalization, home programmes and parents' lost work-days. Resource utilization was estimated by surveying 17 Canadian clinics. The natural history of bleeding and other probabilities were determined from a longitudinal chart review (n = 24) and published literature. EscDose costs an additional $3192 per joint-haemorrhage that was avoided compared with Demand whereas SP costs an additional $9046 per joint-haemorrhage that was avoided compared with EscDose. Clinic costs and lost wages were reduced by 60-80% for EscDose and SP compared with Demand. EscDose attained more QALYs than SP and Demand on account of less bleeding than Demand and lower need for ports than SP. The incremental cost per QALY for EscDose vs. Demand was $542 938. EscDose was less expensive with similar QALYs compared to SP. Sensitivity analysis was performed on all probability- and cost-estimates, and showed the model was sensitive to the cost of FVIII and the SP and target joint utilities. In conclusion, prophylaxis will substantially improve clinical outcomes and quality of life compared to Demand treatment, but with substantial cost.