Physical Fitness of Children, Adolescents and Young Adults With Immune Thrombocytopenic Purpura

Patients with chronic immune thrombocytopenic purpura (ITP) live with an anxiety-inducing risk of haemorrhage that is unpredictable over several months or years. They also rate fatigue as one of the most frequent (48%) and most severe (73%) disabling symptoms, which contributes to a reduced quality of life \[Cooper, 2021\]. In this autoimmune disease targeting platelets, fatigue could be mediated by platelet and immunological abnormalities, and/or promoted by psychobehavioural determinants that are poorly understood in this chronic disease. Since 1980, the World Health Organisation has stated that functional capacity assessments best reflect the impact of chronic diseases on quality of life, with fatigue playing an important role. The association between fatigue and aerobic physical capacity, determined by maximum oxygen consumption (VO2max), has been demonstrated in several pathologies. It is often associated with the vicious circle of deconditioning, where the impact of the disease on cardiac, muscular and respiratory functions is intertwined with inactive or sedentary behaviours. At the end of this vicious circle, adults have been shown to have an increased cardiovascular risk and a high prevalence of anxiety and depression syndromes. VO2max measured by cardiopulmonary exercise testing (CPET) is increasingly used in monitoring, as recommended by the French Society of Cardiology \[Marcadet, 2018;Marcadet, 2019\]. Our team (Amedro et al.) has set up a research programme on aerobic physical capacity and deconditioning to exercise in chronic childhood diseases and has just published the reference values for exercise tests in healthy paediatric populations, enabling the interpretation of VO2max results in sick children \[Gavotto,2023\]. However, it has been demonstrated that the VO₂ plateau is not predominantly reached in healthy adults and is rarely reached (\<25%) in healthy children. \[Armstrong, 1996 ; Åstrand, 1952 ; Rowland, 1992\]. Thus, the highest oxygen consumption measurement (VO2pic) is often used instead of VO2max to define aerobic capacity. We will therefore use the concepts of VO2max and VO2pic in this study. The first population studied by our team was children with congenital heart disease, who showed a significant reduction in their VO2max \[Amedro, 2018\]. Based on these results, a functional rehabilitation programme (QUALIREHAB) was set up and evaluated in a randomised controlled clinical trial \[Amedro, 2019\] . The data demonstrate its positive impact not only on VO2max, but also on quality of life. Aerobic physical capacity was assessed in chronic paediatric diseases without direct cardiac involvement. We have also shown that VO2max declines more rapidly over time in children, adolescents and young adults who have survived childhood cancer \[Gavotto, 2023\] or in children with asthma \[Moreau, 2023\]. To date, no prospective controlled studies have reported on the level of aerobic physical capacity in children, adolescents and young adults with cITP. We therefore hypothesise that fatigue in patients monitored for cITP could be correlated with a decrease in their aerobic physical capacity, causing these patients to enter a 'vicious cycle of deconditioning'. If this hypothesis is verified, an exercise rehabilitation programme could have a positive impact on quality of life, physical health and mental health