Young people with juvenile fibromyalgia report higher pain levels and show greater “functional disability” affecting daily life than do children with other rheumatic diseases, a recent study reports.
However, these findings also suggest that pain scores are less associated with functional disability among children with juvenile fibromyalgia than among children with these other diseases.
The study, “Pain, functional disability, and their Association in Juvenile Fibromyalgia Compared to other pediatric rheumatic diseases,” was published in Pediatric Rheumatology.
Pain is the defining characteristic of juvenile primary fibromyalgia syndrome (JPFS). And in “a subset of youth with JPFS, pain is associated with significant and enduring impairment in the ability to participate in usual activities and maintain positive well-being,” the researchers wrote.
It also significantly impairs the quality of life of young patients with other rheumatic childhood diseases.
Researchers assessed how pain scores tended to compare between diseases, and whether those scores were associated with changes in children’s ability to function.
They analyzed data from the Childhood Arthritis and Rheumatology Research Alliance (CARRA) Legacy Registry, which included data from 56 pediatric rheumatology centers in North America. The analyzed sample included 201 children with JPFS and 7,552 with other childhood rheumatic diseases, namely juvenile dermatomyositis (JDM), systemic lupus erythematosus (SLE), mixed connective tissue disease (MCTD), central nervous system vasculitis or juvenile idiopathic arthritis (JIA). The groups were broadly analyzed as JPFS or ‘other.’
In addition to relevant clinical reports, the data included children’s self-assessed pain, rated on a scale from one to 10 (1o being the most pain). Functional ability was assessed using the Childhood Health Assessment Questionnaire (CHAQ), which covers both an ability to do everyday tasks (like hygiene, grip strength, walking) as well as pain levels and was filled out by the child or the caregiver. The children/caregivers were also asked to rate the extent to which pain impacted their overall well-being on a scale from one to 10 (with 10 representing the biggest impact of the disease, or, put another way, low overall well-being).
Several demographic differences between the groups were noted. On average, children with JPFS were significantly older at the time of data collection (15.5 vs. 13.0 years) and at the time of symptom onset (12.1 vs. 8.3 years) than children with other diseases. JPFS patients were also older at time of the first visit to a rheumatologist (13.7 versus 9.2 years).
The entire sample size was predominantly female, and there was a significantly greater percentage of females in the JPFS group (84% vs. 72%) than among other groups. A higher percentage of JPFS children that other children here had a family history of fibromyalgia or autoimmune disease (18% vs. 4% and 45% vs. 31%, respectively), and JPFS children had a significantly higher average body mass index (24.2 vs. 21.2 kg/m2). Both groups were at least 80% white.
Children with JPFS reported significantly higher average pain scores than those with other rheumatic diseases (6.4 vs. 2.6). Additionally, a greater proportion of children with JPFS reported a pain score of seven or higher (54.7% vs. 11.7%). The lowest average pain scores (1.7) were reported among children with JDM.
After adjustment for age and disease activity, children with JPFS had generally worse functional scores than those with other rheumatic diseases, including a significantly lower average CHAQ scores (0.76 vs. 0.36) and higher disease impact on overall well-being (5.0 vs. 2.5).
Interestingly, pain and functional scores were not very strongly correlated among children with JPFS, as compared to children with other rheumatic diseases. For instance, associations between pain and CHAQ scores were highest among children with MCTD, SLE, JDM, and JIA, and overall well-being and pain were most strongly correlated among children with JIA.
“Patients with JPFS were found in this study to reliably report both higher levels of pain and more impairment in functioning than children with any other rheumatic disease,” the researchers concluded. “The degree to which pain is associated with impairment in functioning and well-being, however, was found to be variable across rheumatic conditions.”
Side effects of treatments given these “other” pediatric patients may be one reason for a closer association between the two, the team added, or pain “may work synergistically with other disease symptoms (e.g., muscle weakness, arthritis) common in these conditions” that impact function.
“Our findings emphasize that pain across conditions commonly managed in pediatric rheumatology would benefit from continued increased prioritization in assessment, treatment and research,” the study said.