A prospective study of patterns of bleeding in boys with haemophilia.

To describe the patterns of bleeding and clotting factor concentrate use in boys with haemophilia over a 6-month period, daily diary records of bleeding, factor use, levels of physical activity, chore performance and school attendance were collected from parents of 96 males between 4 and 17 years of age with haemophilia A or B followed at six comprehensive haemophilia treatment centres in Massachusetts, Rhode Island and Tennessee. 14 243 person days were available for analysis. The sample cohort averaged approximately nine bleeding episodes (1.5 per months), almost two-thirds of which were haemarthroses. 44% of bleeds were associated with injury and the average duration was 1.4 days. New bleeding episodes were significantly more likely to begin on weekdays (Monday-Thursday) than on weekends (Friday-Sunday). Boys with more severe disease had significantly more bleeding episodes and a higher frequency of haemarthroses. Boys with the most severe disease were also more likely to have joints involved when they bled and to have more spontaneous bleedings without apparent preceding trauma. Bleeding was associated with increased school absence, decreased levels of physical activity and decreased rates of household task performance. Relatively high rates of bleeding associated with trauma suggest the need for preventive interventions.