These findings were more pronounced in those with lower limb joint involvement and those who were inactive. This is likely to reflect reduced physical activity and in particular, reduced impact loading activity in children with haemophilia. These findings have been observed both

in populations of children receiving prophylaxis and receiving on-demand therapy [5, 16]. The aim of this study was to evaluate sports participation and the time spent in physical activity, including vigorous physical activity, in children with haemophilia. We were also interested in quantifying inactive time and determining whether children with haemophilia met the Australian government’s guidelines for recommended PS-341 cell line levels of physical activity and small-screen time in children and adolescents. The data reported here were obtained from a case-crossover study nested in a prospective cohort study. Details of that study have been described elsewhere [22]. Children between the ages of 4 and 18 years with moderate or severe haemophilia A or B were eligible for the study. The study was approved by The Human Research Ethics Committees of The University of Sydney and the three recruiting hospital sites. Participants or their parent or guardians gave written, informed consent. Following

recruitment to the study, parents of children with haemophilia were contacted by telephone to record SCH772984 cost characteristics including age, severity of haemophilia, prophylaxis schedule if on prophylaxis, orthopaedic history (including history of known 3-oxoacyl-(acyl-carrier-protein) reductase arthropathy) and the presence of inhibitors. At the same time, an interviewer-assisted modifiable activity questionnaire (Kriska’s MAQ) was administered. The questionnaire has been validated in adolescents and enables estimation of total

hours of activity per week for the past year, average intensity and average hours per week of vigorous activity [23]. Intensity of physical activity was expressed in metabolic equivalents (METS). Activities were allocated a MET value based on the Compendium of Physical Activities classification system [24]. One MET is equivalent to an energy expenditure of 1 kcal kg–1 h–1 or an oxygen consumption of 3.5 mL kg–1 min–1 which is approximately the energy expenditure or oxygen consumption at rest. Moderate intensity physical activity was defined as between 3 and 6 METS and vigorous physical activity was greater than 6 METS. The MAQ also enabled estimation of average daily small-screen recreation time which includes time spent watching television, playing computer games and other small-screen activities. It has been successfully used to measure habitual activity in children and adolescents with cystic fibrosis and has demonstrated test–retest reliability [25]. Participants were followed for one year and bleeding episodes monitored using a weekly short message service (SMS) system.