Abstract
BackgroundAlthough it is widely appreciated that vigorous physical activity can increase the risk of bleeding episodes in children with haemophilia, the magnitude of the increase in risk is not known. Accurate risk estimates could inform decisions made by children with haemophilia and their parents about participation in physical activity and aid the development of optimal prophylactic schedules. The aim of this study is to provide an accurate estimate of the risks of bleeding associated with vigorous physical activity in children with haemophilia.Methods/DesignThe study will be a case-crossover study nested within a prospective cohort study. Children with moderate or severe haemophilia A or B, recruited from two paediatric haematology departments in Australia, will participate in the study. The child, or the child's parent or guardian, will report bleeding episodes experienced over a 12-month period. Following a bleeding episode, the participant will be interviewed by telephone about exposures to physical activity in the case period (8 hours before the bleed) and 2 control periods (an 8 hour period at the same time on the day preceding the bleed and an 8 hour period two days preceding the bleed). Conditional logistic regression will be used to estimate the risk of participating in vigorous physical activity from measures of exposure to physical activity in the case and control periods.DiscussionThis case-control study will provide estimates of the risk of participation in vigorous physical activity in children with haemophilia.
Highlights
It is widely appreciated that vigorous physical activity can increase the risk of bleeding episodes in children with haemophilia, the magnitude of the increase in risk is not known
(b) Determine whether habitual activity is associated with the transient risk of bleeding episodes following physical activity (c) Determine the induction period for a bleed caused by vigorous physical activity
Empirical evidence of the length of the induction period will be sought by examining histograms of the time elapsed between the onset of symptoms of each bleed and the last preceding occasion of physical activity. These histograms will be compared with histograms obtained from the control periods, and with the histograms obtained when participants were interviewed at one randomly selected occasion during the year, to determine the period over which physical activity appeared to contribute to an excess of bleeds
Summary
Haemophilia affects 1 in 7,000 males in Australia.[1]. Clinically, haemophilia is characterised by bleeds, most often into muscles or joints. In addition to guiding prophylactic schedules, good information about the risks of bleeds associated with vigorous physical activity is needed to inform the decisions made by children with haemophilia and their parents about participation in physical activities. This study will provide the first estimates of the risks of bleeding associated with vigorous physical activity in children with haemophilia. The researcher will record participants' contact details and the child's characteristics, including current age, age at diagnosis, type of bleeding disorder, severity of bleeding disorder, estimated number of bleeds in the past 12 months, height and weight (BMI), prophylaxis schedule, habitual activity level, orthopaedic history (including history of known arthropathy and joint arthropathy score) and presence of neutralising antibodies or inhibitors (i.e. inhibitor titre of 0.5 Bethesda units or more [2]). (b) Determine whether habitual activity is associated with the transient risk of bleeding episodes following physical activity (c) Determine the induction period for a bleed caused by vigorous physical activity
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