Collision Sports and Risk of Bleeding in Children With Hemophilia
Authors: Marilyn J. Manco-Johnson
Journal: JAMA (2012)

IN THIS ISSUE OF JAMA, BRODERICK AND COLLEAGUES 1 report results of their study of the association of vigorous sports with bleeding rate in 104 children and adolescents with moderate or severe hemophilia. Most participants were receiving prophylactic infusions of replacement clotting factor, which has been established as the standard of care for children and adolescents with hemophilia. Activities were scored as category 1, 2, or 3, depending on the expected trauma related to frequency and severity of collisions associated with the activity; category 2 and 3 activities can be referred to as collision sports. The study results indicate that the risk of bleeding events requiring acute factor replacement was increased following collision sports, with an odds ratio of 2.7 for category 2 activities (such as basketball or baseball) and 3.7 for category 3 activities (such as wrestling or US football). However, because exposure time to the higher-risk activities was a small percentage of total life hours and because the annual rate of bleeding was low, the absolute increase in risk was low. Additional statistical modeling, in which factor level was inferred from infusion schedule and known recovery and half-life, revealed that each 1% increase in plasma factor activity was associated with a 2% lower bleeding risk, thus suggesting therapeutic strategies that might further reduce the bleeding risk associated with collision sports. The study was strengthened by a novel and robust prospective case-crossover design. Data were acquired for each bleeding event from the 24-hour period preceding the event, as well as the 2 preceding 24-hour periods that served as control time periods during which exposure to sports and factor infusions were compared. To evaluate the accuracy of activity estimates during the control periods, participants were also asked to report their physical activity during randomly chosen times without bleeding events, along with the 2 preceding 24-hour intervals. This accuracy check found activity levels that were comparable with the control periods. The study by Broderick et al expands previous data on injury and bleeding rates related to sports participation in children with severe hemophilia. A study of school-aged children by Ross et al comparing 299 high-impact-sports seasons in 27 children and 46 low-impact-sports seasons in 10 children (92% using clotting factor prophylaxis) found a very low rate and no between-group differences for joint hemorrhage, injuries, or new target joint development related to high-impact sports. Similar bleeding outcomes were found in a study by Tiktinsky et al of 44 children with hemophilia not using prophylaxis. Both studies suggested that bleeding events related to sports in children with severe hemophilia represent a small proportion of total bleeding episodes. Evidence that participation in collision sports does not worsen the outcome of severe hemophilia may seem counterintuitive and inconsistent with conventional wisdom. However, the study by Broderick et al suggests that a factor level below a critical threshold is a more important determinant of bleeding risk than modest exposure to vigorous activities. All children need to feel part of their peer group. The label of a rare disorder, requirements for frequent intravenous infusions, and exclusion from sports intensify a painful sense of being different for children with hemophilia. Hemophilia almost exclusively affects males and peer participation of boys in many societies is centered around competitive sports. Participation in a popular sport can be important to reduce the sense of isolation experienced by many boys with hemophilia. Participation in desired but possibly higher-risk sports may be a strong motivator for positive health-promoting activities such as self-infusion of prophylactic factor replacement, year-round conduct of strengthening exercises, and increased body awareness with early bleed recognition. In the study by Ross et al, all participants, with their parents, underwent counseling regarding the risks and benefits of the sports in question as well as techniques to minimize risks and maximize health benefits. In addition, prophylaxis regimens were carefully reviewed and optimized. The analyses by Broderick et al suggest that higher factor level at the time of collision was preventive for tempo-