Enthesitis-related arthritis is associated with higher pain intensity and poorer health status in comparison with other categories of juvenile idiopathic arthritis: the Childhood Arthritis and Rheumatology Research Alliance Registry

Abstract

Objective: To assess the relative effect of clinical factors and medications on pain intensity, physical function, and health status in juvenile idiopathic arthritis (JIA).

Methods: We conducted a retrospective cross-sectional study of data from children with JIA enrolled in the Childhood Arthritis and Rheumatology Research Alliance (CARRA) Registry. We tested whether clinical characteristics of JIA were associated with pain intensity, physical function, and health status using multivariable linear and ordinal logistic regression.

Results: During the study period, 2571 subjects with JIA enrolled in the CARRA Registry. Ratings of pain intensity, physical function, and health status differed significantly between JIA categories. In comparison to other categories of JIA, subjects with enthesitis-related arthritis (ERA) reported worse pain and function. In multivariable analyses, higher active joint count and current use of nonsteroidal antiinflammatory drugs (NSAID), biologics, or corticosteroids were associated with worse scores on all patient-reported measures. ERA and older age were significantly associated with higher pain intensity and poorer health status. Systemic JIA and uveitis were significantly associated with worse health status. Enthesitis, sacroiliac tenderness, and NSAID use were independently associated with increased pain intensity in ERA. The correlation was low between physician global assessment of disease activity and patient-reported pain intensity, physical function, and health status.

Conclusion: Significant differences in pain intensity, physical function, and health status exist among JIA categories. These results suggest that current treatments may not be equally effective for particular disease characteristics more common in specific JIA categories, such as enthesitis or sacroiliac tenderness in ERA.

Figure 1. Pain and function by JIA category

(A) Proportion of subjects reporting any pain within the past week. Pain was defined as a pain VAS >0. (B) Median and IQR of pain reported by VAS. Significant differences of pain existed across JIA categories (p-value <0.01). (C) Proportion of subjects reporting impaired function, as defined by CHAQ>0, within the past week. (D) Median and IQR of parent child function as reported by CHAQ. Significant differences of function exist across JIA categories using the Kruskal-Wallis test (p-value <0.01). Scores are not adjusted for subject characteristics or disease activity.

Figure 1. Pain and function by JIA category

(A) Proportion of subjects reporting any pain within the past week. Pain was defined as a pain VAS >0. (B) Median and IQR of pain reported by VAS. Significant differences of pain existed across JIA categories (p-value <0.01). (C) Proportion of subjects reporting impaired function, as defined by CHAQ>0, within the past week. (D) Median and IQR of parent child function as reported by CHAQ. Significant differences of function exist across JIA categories using the Kruskal-Wallis test (p-value <0.01). Scores are not adjusted for subject characteristics or disease activity.

Figure 2. Health status by JIA category

The health status question uses a 5-choice response scale, very poor, poor, good, very good, and excellent. Percent based on total number of patients in each JIA category.

Figure 3. Correlation of PGA with self-reported outcomes

Pair-wise correlation between PGA of disease activity and (A) pain intensity, (B) physical function as measured by the CHAQ, and (C) health status. The jitter function was used to randomly place observed values around their true value to avoid overlap with identical values, thus depicting the amount of data at a given value.