Background The physical function is very important component in clinical evaluation of the activity of juvenile idiopathic arthritis (JIA). The most widely used questionnaire for functional assessment is the Childhood Health Assessment Questionnaire (CHAQ¹), which main disadvantage is its length (69 questions) and its lesser applicability for the children of younger age due to its complexity.

Objectives To assess validity of the new, short and simple questionnaire -The Juvenile Arthritis Functionality Scale (JAFS²) on the children with JIA.

Methods The study included 80 consecutive children treated in the Institute of Rheumatology from January 2010 till April 2011, all diagnosed JIA, 56 (70%) girls and 24 (30%) boys, mean age 10.17±4.91years, disease duration 3.68±3.19 years. Construct validity of JAFS questionnaire was tested by comparison with CHAQ, and core set variables of disease activity (laboratory indices, articular indices, parent’s and children’s assessments of overall wellbeing and pain, and the physician assessment of disease activity). It waspredicted that correlation of the two functional status measures will be strong, and the correlation with other JIA activity measures will be moderate to weak. Also, the ability of the JAFS questionnaire to recognize different degrees of disability among patients based on Steinbrocker’s functional class criteria was tested. Spearman correlation coefficient (r), Interclass correlation coefficient (ICC), Kruskal-Wallis test and χ² test were used for statistical analysis.

Results Correlation of both JAFS I CHAQ questionnaires with other JIA activity measures is statistically highly significant (p<0,01), and for all variables it is higher for JAFS than for CHAQ. Correlation of two questionnaires is high (r 0,846 for parents; r=0,898 for children), while the correlation of questionnaires with other JIA activity measures is moderate to low (r<0,7), and corresponds to predicted correlation. The level of concordance between parents and children are high for both questionnaires (ICC 0,81 for JAFS; ICC 0,87 for CHAQ). There is statistically significant difference of total JAFS score and JAFS subscale scores for lower limbs and hand/wrist, among patients belonging to different functional classes according to Steinbrocker’s functional class (χ²8,427; χ² 8,774; χ² 10,787 p<0,05).

Conclusions JAFS questionnaire shows equally good, even better, construct validity compared to CHAQ on the patients with JIA, it has good discriminative ability, so it can be considered as adequate tool for assessment of functional status of children with JIA.

References

1. Singh G, Athreya BH, Fries JF, Goldsmith DP. Measurement of health status in children with juvenile rheumatoid arthritis. Arthritis Rheum 1994;37:1761–9.

2. Filocamo G, Sztajnbok F, Cespedes-Cruz A, Magni-Manzoni S, Pistorio A, Viola S, et al. Development and validation of a new short and simple measure of physical function for juvenile idiopathic arthritis. Arthritis Rheum2007;57(6):913-20.

Disclosure of Interest None Declared