Assessment of Aerobic Capacity and Other Cardiopulmonary Parameters in Children with Juvenile Idiopathic Arthritis

Introduction: Juvenile idiopathic arthritis (JIA) is the most common chronic rheumatic disease in children. It is believed that children with JIA have lower cardiopulmonary capacity and worse exercise tolerance. The gold standard for assessing physical fitness is aerobic fitness, commonly referred to as the maximum or peak oxygen uptake volume (peakVO₂) measured during a maximum load exercise test. Reduced aerobic fitness may play a key role in predicting the health of JIA patients as it has been associated with cardiovascular diseases and increased adult mortality. Methods: The aim of this study was to assess the oxygen capacity of adolescents with JIA along with other cardiopulmonary parameters in order to determine a group of patients with increased risk of developing cardiovascular diseases in comparison with healthy individuals. Patients were assessed based on parameters such as age, sex, type of JIA, laboratory parameters, physical activity, and treatment. Results: Patients with JIA had lower median values of peakVO₂ (29.05 vs. 38.02 mL/min/kg, p < 0.001), as well as other crucial cardiopulmonary parameters, such as O₂ pulse, minute ventilation, oxygen uptake efficiency slope, and cardiac output than in the healthy control group. The ventilatory anaerobic threshold was achieved earlier and at lower VO₂ values in children with JIA (p = 0.0001). Children with JIA also had lowered respiratory parameters such as maximal voluntary ventilation (p = 0.0031) and tidal volume (p = 0.0002). Patients who were physically active (moderate-intensity physical activity lasting at least 60 min per day) had significantly higher peakVO₂ (p = 0.0099) and ΔVO₂/ΔWR relationship (p = 0.0041) values than JIA patients who were not physically active. Conclusions: Children with JIA show moderate to severe physical impairment. Reduced physical fitness and a low level of activity might be associated with further deterioration of patient's condition, which might contribute to increased risk of cardiovascular disease, social exclusion and deterioration of quality of life in this group of patients. Exercise programs that improve aerobic fitness and increase muscle strength should be individualized and modified based on the individual needs and capabilities of the patient.