Background/Purpose:

Physical activity (PA) is an important component of health, and is essential for optimal growth and development. Children with juvenile idiopathic arthritis (JIA) are reported to have lower PA levels than healthy peers, but most reported studies are cross-sectional and have included small patient numbers. The LEAP study is a large prospective study of children and youth with JIA, conducted at 12 centres in Canada, that aims to describe the trajectory of PA and its relationship to disease factors, quality of life, inflammation, and bone and muscle function. Here we report baseline PA at the time of LEAP study entry, and its association with these factors in children with JIA compared to healthy peers.

Methods: All patients with definite JIA (ILAR criteria) enrolled in the LEAP study between 2012-2015 who completed baseline visits were included. Patients had either newly diagnosed JIA (enrolled within 6 months of diagnosis), or previously diagnosed JIA (enrolled > 2yrs after diagnosis). The Physical Activity Questionnaire (PAQ) was the primary outcome. This 7 day self report tool is scored from 1 (very low PA) to 5 (high PA). We compared the PAQ for JIA patients to standard population normative values. The clinician completed demographic and clinical data, including a physician global assessment of disease activity (PGDA; VAS 0-100), while patient/parent-report outcomes included the Juvenile Arthritis Quality of Life Questionnaire (JAQQ), and the Childhood Health Assessment Questionnaire (CHAQ). Descriptive statistics and tests of association were performed using STATA.

Results: Of the 573 patients included (69% female, mean age 12.1 ±2.6 yr), 166 had newly diagnosed JIA and 407 had previously diagnosed JIA (median disease duration 0.3 and 5.8 yr respectively). The mean PAQ score was lower overall for children with JIA (mean 2.61, SD 0.75) compared to a healthy population (mean 2.75, SD 0.6) (p<0.001). Newly diagnosed JIA patients had a lower PAQ score (median 2.54. IQR 2.4,2.6) than those with longer disease duration (median 2.64, IQR 2.5, 2.7) (p=0.003). PAQ score varied significantly (p=0.0059) by JIA disease subtype, with lowest scores in patients with RF + polyarthritis (PAQ 2.15, IQR 1.9, 2.39) and enthesitis related arthritis (PAQ 2.48, IQR 2.29, 2.67 ); children with systemic JIA, oliogarticular persistent, psoriatic and undifferentiated subtypes had mean PAQ scores higher than 2.65. Variables associated with lower PAQ score included older age, higher number of active joints, and worse PGDA, JAQQ and CHAQ scores. Self-reported pain and gender were not associated with the PAQ score.

Conclusion: This large pan-Canadian study confirms that children with JIA have lower PA levels than healthy peers. PA is lower at diagnosis and in early disease compared to later in disease, and children with RF+ polyarthritis and ERA have lower PA levels. Children and youth with higher disease activity report lower PA, lower functional status and lower health related quality of life.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/physical-activity-in-canadian-children-with-juvenile-idiopathic-arthritis-the-leap-study-linking-exercise-activity-and-pathophysiology-in-canadian-children-with-arthritis/