Trajectories of pain severity in juvenile idiopathic arthritis: results from the Research in Arthritis in Canadian Children Emphasizing Outcomes cohort

Abstract

We studied children enrolled within 90 days of juvenile idiopathic arthritis diagnosis in the Research in Arthritis in Canadian Children Emphasizing Outcomes (ReACCh-Out) prospective inception cohort to identify longitudinal trajectories of pain severity and features that may predict pain trajectory at diagnosis. A total of 1062 participants were followed a median of 24.3 months (interquartile range = 16.0-37.1 months). Latent trajectory analysis of pain severity, measured in a 100-mm visual analogue scale, identified 5 distinct trajectories: (1) mild-decreasing pain (56.2% of the cohort); (2) moderate-decreasing pain (28.6%); (3) chronically moderate pain (7.4%); (4) minimal pain (4.0%); and (5) mild-increasing pain (3.7%). Mean disability and quality of life scores roughly paralleled the pain severity trajectories. At baseline, children with chronically moderate pain, compared to those with moderate-decreasing pain, were older (mean 10.0 vs 8.5 years, P = 0.01) and had higher active joint counts (mean 10.0 vs 7.2 joints, P = 0.06). Children with mild-increasing pain had lower joint counts than children with mild-decreasing pain (2.3 vs 5.2 joints, P < 0.001). Although most children with juvenile idiopathic arthritis in this cohort had mild or moderate initial levels of pain that decreased quickly, about 1 in 10 children had concerning pain trajectories (chronically moderate pain and mild-increasing pain). Systematic periodic assessment of pain severity in the months after diagnosis may help identify these concerning pain trajectories early and lay out appropriate pain management plans. Focused research into the factors leading to these concerning trajectories may help prevent them.

The pain trajectory of juvenile idiopathic arthritis (JIA): translating from adolescent patient report to behavioural sensitivity in a juvenile animal model

“…Divergent pain trajectories have been shown previously in JIA [8–10]. Studies describe a consistently low pain trajectory in many patients (≥50%) and a persistently high pain trajectory in 11.1% [8] or 17.9% [9] of patients, lower than reported here (24.2%).…”

“…Recent studies show that only a subset of children with JIA (10–20%) develop persistent pain over 5 years from disease onset [8–10]. These findings suggest that pain sensitivity may vary in JIA patients and that certain biological and psychosocial factors may contribute to this sensitivity and the development of persistent pain.…”

“…These findings suggest that pain sensitivity may vary in JIA patients and that certain biological and psychosocial factors may contribute to this sensitivity and the development of persistent pain. Age, [8–11] sex, [8, 12, 13] JIA subtype and arthritic activity, [10–12], disease duration, [9] symptoms of depression or anxiety, [3, 13, 14] stressful events [4], and dysfunctional health beliefs [15, 16] have all been implicated as possible contributing factors. However, evidence for the role of these factors in the development of pain is mixed.…”

“…However, evidence for the role of these factors in the development of pain is mixed. For example, the role of arthritic activity is disputed with some studies finding that the presence of active arthritis had no effect on pain sensitivity [13, 17] and others finding that increased numbers of inflamed joints are linked to a more persistent pain state in the following days [3] to years [8, 10].…”

Treating juvenile idiopathic arthritis to target: what is the optimal target definition to reach all goals?

“…As Lomholt put it: "pain was still a problem for a subgroup of children though they were in remission with biological agents" [17]. In a trajectory analysis, Shiff et al reported that disease activity only accounted for a small portion of variability in pain severity in children with JIA [18]. The same picture emerged for fatigue: although fatigue is a prominent feature in many JIA patients, disease activity seems not to be directly related to it [19][20][21].…”