Assessing the test–retest reliability and smallest detectable change of the Haemophilia Activities List

Introduction The Haemophilia Activities List (HAL) is a preferred instrument to measure self‐reported limitations in activities in persons with haemophilia (PWH). Information on reliability and interpretability of HAL scores is lacking. Aim To examine the test‐retest reliability and smallest detectable change (SDC) of the HAL in adult PWH. Methods Fifty adult (≥18 years) persons with mild to severe haemophilia completed the HAL (42 items, 7 domains, optimum 100) at baseline (T0) and 3‐4 weeks later (T1). The intraclass correlation coefficient (ICC) and SDC were calculated for sum and component scores. Results Fifty persons with haemophilia were included (median age 49 years; 92% haemophilia A; 70% severe haemophilia). The median (interquartile ranges) HAL sum score was 77 (62 to 99) at T0 and 81 (64 to 98) at T1. Reliability was good with ICCs for sum and component scores >0.9. The SDC for the sum score was 10.2, for the upper extremity component score 9.2, for the basic lower extremity component score 16.7 and for the complex lower extremity component score 13.4. Conclusion The HAL has a good reliability for the sum and component scores. Score changes of the normalized sum HAL score greater than the SDC 10.2 indicate that the change was not a result of measurement error.