Background: Physical activity (PA) is essential throughout growth and maturation and may offer potential preventive and therapeutic benefits in young patients with juvenile idiopathic arthritis (JIA) [1]. Valid and reliable assessment of children’s many spontaneous and impulsive movements in everyday life is a major challenge, but essential for deriving targeted interventions to promote active lifestyles.

Objectives: Since to date little is known about directly measured 24-hour movement behaviour in adolescents with JIA, we aimed to 1) examine levels of PA and sedentary time (ST) in a sample of adolescent JIA patients in relation to sociodemographic and JIA-related factors and 2) compare levels of PA and ST to population controls.

Methods: Patients with JIA aged 12 to 20 years were eligible for the multicenter ActiMON study. Recruitment took place at seven pediatric rheumatology centers distributed throughout Germany. PA and ST were assessed by an accelerometer (ActiGraph wGT3X-BT, ActiGraph LLC, Pensacola, FL), wearing laterally on the right hip for 7 consecutive days during all awake hours. In order to assess PA patterns in everyday life, accelerometer data were gathered during school weeks only. Device-measured PA were linked to clinical data from the National Pediatric Rheumatological Database (NPRD). Patients’ PA levels were compared with an age-, sex- and BMI-stratified nationwide sample from the MoMo study, in which the same study protocol was used [2]. In accordance with the International Children’s Accelerometry Database criteria [3], subject datasets had to contain validated wear time at least on 4 weekdays and 1 weekend day during their measurement period to be eligible for further data processing and statistical analysis.

Results: Data of 125 patients (mean age 15.2 ± 2.1 years, female 67%, patients’ disease duration 7.2 ± 4.8 years, polyarthritis 30%, cJADAS-10 2.3 ± 2.4) and 455 controls (mean age 14.6 ± 2.6 years, female 66%) were available for evaluation.

Overall, 22% of patients and 14% of controls fulfilled the World Health Organization’s (WHO) PA recommendation of ≥60 min of daily moderate to vigorous PA (MVPA) on average. Almost 86% of patients’ and 76% of controls’ wearing time were identified as ST, followed by PA in light (8% vs. 19%), vigorous (4% vs. 3%), and moderate (2% vs. 2%) intensity. Female patients spent more time sedentary than males (p=0.023), while late adolescent patients spent more time sedentary than early adolescent patients ( p =0.012). Age and the amount of time spent sedentary correlated positively (r=0.32, p<0.001). Patients with polyarticular disease spent on average less time in MVPA than patients with oligoarticular disease course ( p =0.046). No associations were found between average time in MVPA/ST and disease activity (cjadas-10), functional ability (C-HAQ), and pain intensity (NRS 0-10).

Conclusion: Adolescents with JIA were more likely to achieve the WHO recommended minimum level of PA, but spent significantly more time sedentary than German population controls. Since movement behaviour was largely independent of common disease-specific symptoms/barriers, targeted interventions to promote PA and health behaviour change involving multidisciplinary approaches appear urgently needed in this population.

ActiMON as part of the research network TARISMA is funded by the Federal Ministry of Education and Research (01EC1902F).

REFERENCES: [1] Rochette E et al. Physical activity as a promising alternative for young people with juvenile idiopathic arthritis: Towards an evidence-based prescription. Front Immunol 2023;14:1119930.

[2] Burchartz A et al. Measurement of physical activity and sedentary behavior by accelerometry among a nationwide sample from the KiGGS and MoMo Study: Study Protocol. JMIR Res Protoc 2020;9:e14370.

[3] Sherar LB et al. International children’s accelerometry database (ICAD): design and methods. BMC Public Health 2011;11:485.

Acknowledgements: We thank all patients and their parents as well all physicians and study nurses for their participation in ActiMON.

Disclosure of Interests: None declared.