Measuring Clinical Response and Remission in Juvenile Idiopathic Arthritis

Table 1.

Characteristics of Disease Outcome Measures

Table 2.

Pediatric Core Set Components

Table 3.

Disease Activity Score (DAS) Components and Equations for the DAS and DAS28

Table 4.

Clinical Remission in Juvenile Idiopathic Arthritis

processing....

Measures of Joint Damage

While evidence of joint damage, as measured radiographically, has been associated with functional disability in JIA,^[23] no standards for grading radiographic findings or for the follow-up of radiographic images during the disease course are routinely in use. Radiographic outcomes, including joint space narrowing and erosions, are difficult to evaluate in children secondary to changing ossification centers and growth variation, particularly in the setting of chronic illness. In addition, damage visible on radiographs tends to reflect past damage, rather than the current disease state. It has therefore been difficult to incorporate these findings into the standard JIA outcome measures.

A recent report compared two radiographic grading systems used in adult rheumatoid arthritis: the Sharp method and Larsen score, to the Poznanski score in the scoring of wrist radiographs from 25 children with JIA with follow-up radiographs obtained over 5 years.^[24] The Sharp method grades 18 areas of the wrist for joint space narrowing and 17 areas for erosion, while the Larsen score grades radiographic findings on a continuous scale from 0 to 120, based on the appearance of the joint space and presence of erosions. For the purposes of this study, both scoring systems were modified for use in children with the exclusion of interfaces that would not yet be ossified. The Poznanski score has been used in children with JIA and other skeletal diseases and is based on radiometacarpal lengths.^[25] Good interclass correlation was found between the two adult measures (r > 0.9) and moderate correlation was found between these two measures and the Posznanski score for wrist radiograph findings (r > 0.7). In addition, changes within each of the three scores were found to correlate moderately well with active joint count, number of joints with restricted motion, and CHAQ scores.

MRI and ultrasound are both being studied for use in JIA, but standardized measures are not currently in use.^[26] Contrast-enhanced MRI has the advantage of being extremely sensitive for detecting active disease and for the early detection of cartilage loss, bone erosions, and synovial hypertrophy in children.^[27] Bone edema, as detected on MRI, has been associated with the development of erosions and may be a useful reflection of treatment efficacy.^[28] While ultrasound is useful for detecting effusions, imaging joint cartilage, and visualizing synovial hypertrophy, it does not provide similar information as MRI regarding the presence of active disease.^[29]