The Juvenile Arthritis Functional Status Index (JASI): a validation study

Area of Science:

• Pediatric Rheumatology
• Rehabilitation Medicine
• Health Outcomes Measurement

Background:

• Juvenile rheumatoid arthritis (JRA) significantly impacts children's daily living and functional mobility.
• A validated instrument is needed to comprehensively assess functional status in pediatric patients with JRA.
• The Juvenile Arthritis Functional Status Index (JASI) was developed to address this need.

Purpose of the Study:

• To evaluate the reliability and validity of the Juvenile Arthritis Functional Status Index (JASI) in children with JRA.
• To assess the JASI's ability to measure functional tasks across various domains of daily life.
• To determine if children aged 8 and older can provide realistic self-reports on functional abilities.

Main Methods:

• The JASI was administered to 30 children (ages 8-19) with JRA at three time points (baseline, 3 weeks, 3 months) to assess test-retest reliability.
• Construct validity was evaluated using established rheumatology measures (e.g., joint count, grip strength, functional class).
• Child self-reports were compared with therapist observations for agreement.

Main Results:

• JASI Part I demonstrated excellent test-retest reliability (ICC > 0.95) for both retest intervals.
• JASI Part I scores showed strong correlations with multiple rheumatology measures (r > 0.50), confirming construct validity.
• There was fair to good agreement between child self-reports and therapist observations, supporting realistic reporting from age 8.

Conclusions:

• JASI Part I is a reliable and valid functional measure for school-aged children and adolescents with JRA.
• The self-report feature of JASI Part I is considered realistic for children as young as 8 years old.
• Further research is ongoing to evaluate JASI's responsiveness to change and compare its sensitivity with other JRA functional measures.