Background/Purpose:   Although children with JIA have lower fitness levels than healthy peers, little is known about their level of habitual physical activity.   The LEAP study is a prospective longitudinal multicentre study of children and teens with JIA, aimed at describing the trajectory of physical activity (PA) in JIA, and its relationship to disease factors, inflammation, quality of life, bone health and muscle function.  Here we report PA levels of children and teens with JIA in early and late disease at study entry.

Methods: We enrolled patients with JIA (aged 8-16 y) at 12 pediatric rheumatology centres in Canada as either an inception cohort (early disease; within 6 months of diagnosis) or an established disease cohort (late disease; > 2yr after diagnosis).  We assessed PA with a validated Physical Activity Questionnaire for children (PAQ-C, age 8-13 y) or teens (PAQ-A, age 14-16 y).  This 7-day recall self-report tool has scores from 0 (no PA) to 5, high level ofPA.  Participants record weekly PA across a wide range of activities and sports; normative data has been published.   Patients completed a pain scale (VAS 0-100), the Childhood Health Assessment Questionnaire (CHAQ), and Juvenile Arthritis Quality of life Questionnaire (JAQQ). Examining physicians recorded physician global assessment of disease activity (VAS 0-100) and presence of active joints.   We used descriptive statistics and two-way ANOVA to assess differences between groups.  We used PAQ standard population normative values to compare to JIA patients (female 2.69, SD 0.62; male 3.0 SD 0.72). 

Results: We collected complete PA data from 127 patients (85 F, 42 M, med age 9.5 y) from March 2012-April 2013.  The early cohort included 49 patients (enrolled median 1.2 mo after diagnosis) and the late cohort included 78 patients (enrolled median 3.3 yr after diagnosis).    Active arthritis was found in 48 patients, with a mean of 5.4 active joints (range 1-56);  PGA was a mean of 12.7 (range 0-74).  Overall mean PAQ score for the JIA patients was 2.6 (SD 0.73, range 1-4).Table 1 describes PAQ scores by sex, disease cohort, and presence of active arthritis.  When controlled for sex, PAQ scores were significantly different between new onset and late disease.   Factors significantly associated with PAQ score included patient-reported pain (p=0.001), CHAQ score (p<0.0001), JAQQ score (p=0.0001), number of active joints (p=0.002) and PGA (p=0.001); ESR and presence of joints with limited range of motion were not associated with PAQ score. 

Table  1.    PAQ scores in patients with JIA

	Total	Female (mean.SD)	Female z-score (mean, SD)	Male (mean, SD)	Male z-score (mean, SD)
Total	2.5 (O.73)	2.4 (0.66)	-0.46 (1.08)	2.71 (0.822)	-0.39(1.14)
Early disease	2.34(0.73)	2.31(0.67)	-0.60(1.08)	2.38(0.85)	-0.85(1.18)
Late disease	2.60(0.71)	2.45(0.66)	-0.38(1.07)	2.96(0.72)	-0.05(1.0)
Active joints present	2.27(0.68)	2.12(0.6)	-0.92 (0.97)	2.56(0.76)	-0.61(1.06)
No active joints	2.68(0.71)	2.62(0.63)	-0.10(1.01)	2.81(0.86)	-0.44(1.14)

Conclusion:   Children with JIA reported significantly lower levels of PA than healthy peers; this was especially evident in girls, patients with active arthritis, and early in disease.  Disease activity, self reported quality of life and functional status may play a role in moderating PA in JIA.  The longitudinal data collection of the LEAP study will provide important insight into factors associated with poor PA in JIA.

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