Development and validation of a new short and simple measure of physical function for juvenile idiopathic arthritis

Giovanni Filocamo, Flavio Sztajnbok, Adriana Cespedes-Cruz, Silvia Magni-Manzoni, Angela Pistorio, Stefania Viola, Nicolino Ruperto, Antonella Buoncompagni, Anna Loy, Alberto Martini, Angelo Ravelli

Research output: Contribution to journalArticlepeer-review


Objective. To develop and validate a new short and simple measure of physical function in children with juvenile idiopathic arthritis (JIA). Methods. The Juvenile Arthritis Functionality Scale (JAFS) is a 15-item questionnaire that explores physical function in 3 body areas (lower limbs, hand/wrist, and upper segment). Validation of the Italian version of the instrument was accomplished by evaluating 211 consecutive JIA patients ages 2.2-18 years. The instrument's feasibility, face and content validity, construct and discriminative ability, internal consistency, interrater reliability, and responsiveness to clinical change were examined. JAFS psychometric properties were compared with those of the Childhood Health Assessment Questionnaire (C-HAQ). Results. The JAFS was found to be feasible and to possess both face and content validity. The JAFS score correlated with most of the other JIA outcome measures in the range predicted, thereby demonstrating good construct validity, and discriminated well among different levels of disability. The internal consistency (Cronbach's alpha) was 0.82. The intraclass correlation coefficients between raters (mothers, fathers, and children) and between reported and observed level of function ranged from 0.65 to 0.84. The JAFS revealed fair responsiveness, with a standardized response mean ranging from 0.42 to 0.56. Comparison with the C-HAQ indicated that the JAFS may be superior in terms of construct validity and reliability, and at least as good in terms of discriminant validity and responsiveness. Conclusion. The JAFS exhibited good reliability, construct validity, and discriminative ability and fair responsiveness, and is therefore a valid instrument for the assessment of physical function in children with JIA.

Original languageEnglish
Pages (from-to)913-920
Number of pages8
JournalArthritis Care and Research
Issue number6
Publication statusPublished - Aug 15 2007


  • Disability
  • Functional assessment
  • Health outcomes
  • Juvenile idiopathic arthritis

ASJC Scopus subject areas

  • Rheumatology


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