Physical (in)activity and screen-based media use of adolescents with juvenile idiopathic arthritis over time - data from a German inception cohort.

Background: Regular physical activity (PA) has been proven to help prevent non-communicable diseases and is beneficial for disease management in chronically ill populations. Physical inactivity and recreational screen-based media (SBM) use are related to poor health outcomes and common among youth. This study aimed to (1) investigate PA levels and recreational SBM use of adolescents with JIA over time and (2) compare these behaviours with those of their peers.

Methods: Data from JIA patients and their peers enrolled in the inception cohort study ICON at 11 German centers were analyzed. Individuals aged 13 and over were followed prospectively with questionnaires concerning PA level, recreational SBM use, and health-related quality of life (HRQoL) at a two-year interval. Group by time interactions were analyzed using linear mixed models.

Results: Data of 214 patients (mean age at first documentation 14.4 ± 0.9 years, female 63%) and 141 peers could be considered. At first documentation, patients were less physically active compared to their peers (p < 0.001). In contrast to their peers, patients' PA levels increased over time (OR 3.69; 95% CI: 1.01-13.50, p = 0.048). Mean screen time did not differ significantly between patients and peers (first documentation: 3.5 h vs. 3.0 h, p = 0.556; follow-up: 3.6 h vs. 3.3 h, p = 0. 969). During the observation period, male patients reported higher PA levels than female patients, but also higher screen time levels. While low socioeconomic status (SES) (OR 14.40; 95%-CI: 2.84-73.15) and higher cJADAS-10 score (OR 1.31; 95%-CI: 1.03-1.66) increased the likelihood for high SBM use (≥ 4.5 h/d), higher PedsQL psychosocial health score (OR 0.93; 95%-CI: 0.88-0.99) was associated with a decreased likelihood.

Conclusions: Adolescents with JIA become more physically active over the disease course and achieve comparable levels of PA and recreational screen time to their peers. However, the vast majority appear to be insufficiently physically active. Future interventions to promote healthy lifestyles should include gender and SES as important determinants to reach most vulnerable groups.