Decreased pain threshold in juvenile idiopathic arthritis: a cross-sectional study.

Objective: To examine the pain threshold in children with juvenile idiopathic arthritis (JIA) compared with healthy children by using a digital pressure algometer.

Methods: Fifty-eight children with JIA born between 1995 and 2000 and 91 age-related healthy children participated in the study. We used a digital pressure algometer to measure the pain threshold on 17 symmetric, anatomically predefined joint-related or bone-related areas. All children were asked to rate their current pain on a Faces Pain Scale, and parents of children with JIA were asked to complete a parental revised version of the Child Health Assessment Questionnaire (CHAQ-R). Clinical data were registered on children with JIA.

Results: The pain threshold was significantly lower among children with JIA (total mean PT = 1.33 ± 0.69 kg/cm(2)) when compared with the healthy control group (total mean PT = 1.77 ± 0.67 kg/cm(2)). The same pattern was found in all areas measured, including negative control areas that are normally unaffected in JIA (p = 0.0001 to 0.005). Overall, the pain threshold was 34% lower in females than in males in both groups (p < 0.0001). We found no correlation between pain threshold and age, current pain experience, disease duration, or disease activity.

Conclusion: Children with JIA had a substantially lower pain threshold even in areas usually unaffected by arthritis. Our findings suggest that JIA alters the pain perception and causes decreased pain threshold.