Aerobic capacity and disease activity in children, adolescents and young adults with juvenile idiopathic arthritis (JIA)

Abstract

Background: As patients with juvenile idiopathic arthritis (JIA) progress into adulthood, long-term outcome is determined by disease activity, physical and psychosocial development. Decreased aerobic capacity may play a critical role in health-related outcomes in JIA, since it has been linked with cardiovascular morbidity and mortality in late adulthood. The objectives of the current study are to examine the aerobic capacity and its relation to parameters of disease activity in children, adolescents and young adults with JIA.

Methods: Sixty-three patients with JIA (aged 10-27 years) were cross sectional studied regarding their aerobic capacity and correlations were made to demographic, disease-related variables, and medication utilization. in a cross-sectional study group of 63 patients of all subtypes. Patients were divided in three age groups, 10-13 years; 14-17 years and 18-27 years.

Results: Reduced aerobic capacity is found in clinical remission as well as active disease in all subtypes and all age groups. Aerobic capacity is more impaired in active disease shown by DAS 28, JADAS 27, ESR and serum thrombocyte counts. Lower haemoglobin has a negative impact. Long-term used medication including methotrexate and corticosteroids didn't influence outcome. There is no association with current sports participation.

Conclusion: Reduced aerobic capacity is present in children and adolescents with JIA, both in active disease and in patients with remission. Measures of aerobic capacity may serve as important outcome measure in JIA.

Figure 1

Aerobic capacity (expressed as median Z-score of VO_2peakand VO_2peak/kg) in relation to age in adolescents and young adults with JIA. Z scores are compared to age and sex related healthy controls (p-values <0.01). Abbreviations: Z-score_: standard deviation of the individual patient compared with values from age- and sex- related historical Dutch controls(37); VO_{2peak abs}: highest oxygen uptake in liters of oxygen per minute (l/min) during maximum exercise test in l/min; VO_2peak/kg_l : highest oxygen uptake in milliliters of oxygen per kilogram of bodyweight per minute (ml/min/kg) during maximum exercise.

Figure 2

Aerobic capacity (expressed as Z-score of VO_2peakand VO_2peak/kg) in relation to disease activity in adolescents and young adults with JIA in remission and with active disease. Z scores are compared to age and sex matched healthy controls (* p-values <0.05; **p-values <0.01). Abbreviations: Z-score_: standard deviation of the individual patient compared with values from age- and sex- related historical Dutch controls(37); VO_{2peak abs}: highest oxygen uptake in liters of oxygen per minute (l/min) during maximum exercise test in l/min; VO_2peak/kg_l : highest oxygen uptake in milliliters of oxygen per kilogram of bodyweight per minute (ml/min/kg) during maximum exercise; AJC: Active Joint Count; DAS28: Disease Activity Score of 28 joints.