The relationship between impairments in joint function and disabilities inindependent function in children with systemic juvenile idiopathic arthritis

Objective. Knowledge about the impact of joint impairment on functional abi lity is needed in planning care and setting treatment goals in children wit h juvenile idiopathic arthritis (JIA). We investigated the relationship bet ween joint impairments and upper and lower limb function. Methods. Twenty-one children with systemic JIA with an average age of 9.2 y ears and a mean disease duration of 4.8 years participated in this study. J oint impairments were assessed by the following variables: joint counts on swollen (JCS) and tender (JCT) joints and the loss of joint motion as deter mined by the Joint Alignment and Motion scale (JAM). Functional performance and functional ability were determined by the Juvenile Arthritis Functiona l Assessment Scale (JAFAS) and Childhood Health Assessment Questionnaire (C HAQ), respectively. The relationship between impairments and functional dis abilities was studied at the level of (1) the complete instruments, (2) upp er and lower limb function separately, and (3) the individual joints and it ems. Results. Regarding complete instruments, the Spearman rank correlation betw een functional disabilities and loss of joint motion was moderate to good ( JAM/CHAQ r(s) = 0.66, JAM/JAFAS r(s) = 0.77). A fair correlation was found between functional disabilities and the joint count on swollen joints (JCS/ CHAQ r(s) = 0.45, JCS/JAFAS r(s) = 0.52), but no significant relationship w as found with the number of tender joints (JCT/CHAQ r(s) = 0.02, p > 0.05, and JCT/JAFAS r(s) = 0.14, p > 0.05). At the extremity level (upper and low er limb function), the relationship between functional disabilities and the loss of joint motion appeared to be stronger in the lee than in the arm. A t the level of the individual joints and questionnaire items, loss of joint motion in hip or shoulder joint appeared to be the most important factor i n predicting limitation in leg or arm function. Conclusion. Our study shows that with respect to joint impairments, loss of joint motion is the strongest indicator of functional disability in childr en with systemic JIA. Loss of joint motion has a greater effect on lower li mb function.