Validation of the Haemophilia & Exercise Project-Test-Questionnaire (HEP-Test-Q)-An instrument for the assessment of subjective physical functioning in children with haemophilia

INTRODUCTION: Contemporary haemophilia management recommends sport and physical activity in children with haemophilia. Assessment of subjective physical functioning requires standardized and validated instruments.

AIMS: To adapt and psychometrically test the adult Haemophilia & Exercise Project-Test-Questionnaire (HEP-Test-Q) for children (aged 6-17 years).

METHODS: In discussion rounds with children, single items of the adult HEP-Test-Q were reformulated to make them understandable without changing the item concept. The validation of the child-adapted version in children with haemophilia (n = 228) included pre-testing with feasibility testing, cognitive interviewing (n = 34), pilot-testing of the revised version in the EIS Study (n = 67) and field-testing in the SO-FIT Study (n = 127).

RESULTS: Pre-testing revealed a completion time of 8.2 ± 4.1 minutes and children liked the instrument. Cognitive interviews demonstrated that most items were easy to understand; 9 items were reformulated. Pilot-testing demonstrated good psychometric characteristics in terms of reliability (α = .94 Total Score) and validity. Convergent validity testing showed moderate correlations with the Haemo-QoL (r = -.491), but low correlations with the Petrini Score (r = -.293). Known groups' validity revealed significant differences in clinical subgroups; chronic pain (P < .002) and target joints (P < .021). Field-testing confirmed psychometric characteristics; Cronbach's alpha ranged from α = .80 ("endurance") to α = .94 (Total Score). The child-adapted HEP-Test-Q showed moderate correlations with the PedHAL (r = .634, P < .0001) and the Haemo-QoL SF (r = -.575, P < .0001). Known groups' validity testing proved that the HEP-Test-Q could discriminate between clinical subgroups.

CONCLUSION: The child-adapted HEP-Test-Q is a short, practical and acceptable instrument for the assessment of subjective physical functioning. Outcomes can be compared to adults because item concepts are identical to the adult version.