Validity and Reliability of the International Physical Fitness Questionnaire and the Self-Perceived Health-Related Physical Fitness Questionnaire in Children and Adolescents With JIA and FMF

Juvenile Idiopathic Arthritis (JIA) and Familial Mediterranean Fever (FMF), two of the most prevalent pediatric rheumatologic diseases, significantly compromise the physical health of children and adolescents, leading to reduced physical fitness, muscle weakness, and a sedentary lifestyle. This study aims to evaluate the validity and reliability of the International Fitness Scale (IFS) and the Self-Perceived Health-Related Fitness Questionnaire for Children (PHFQ-C) as assessment tools for physical fitness in individuals diagnosed with JIA and FMF. Our hypothesis is that these scales will provide demonstrably reliable and valid data within this patient population. To test this, 98 patients aged 10-18 years, recruited from the Pediatric Rheumatology Clinic at Istanbul Faculty of Medicine, will participate. Their physical fitness will be objectively measured using the FitnessGram Test Battery (assessing aerobic capacity, muscular strength, and flexibility), while the IFS and PHFQ-C will be administered online. Statistical analysis, conducted using SPSS 25.0, will employ Pearson/Spearman correlation for validity and Cronbach's alpha and test-retest Intraclass Correlation Coefficient (ICC) for reliability. The expected findings will confirm the utility of the IFS and PHFQ-C as practical, economical, and valid instruments for assessing physical fitness in children and adolescents with JIA/FMF. Promoting the widespread use of these scales in clinical settings will facilitate the rapid and convenient evaluation of patients' fitness levels, thereby enabling the development of early, targeted intervention strategies and ultimately contributing to an improved quality of life. Furthermore, by offering a validated alternative to standard test batteries-which are often cumbersome due to requirements for time, specialized equipment, and expert personnel-this work will make a valuable methodological contribution to the existing scientific literature.