Measuring patients' perceptions on their functional abilities: validation of the Haemophilia Activities List

Abstract

Recently, the Haemophilia Activities List (HAL), a haemophilia-specific self-assessment questionnaire to assess a patient's self-perceived functional ability, was introduced and a limited pilot study warranted its further development. The present study finalizes the HAL and assesses the convergent and construct validity, as well as the internal consistency of its definitive version. Three questionnaires (HAL, Dutch-Arthritis Impact Measurement Scales 2 and the Impact on Participation and Autonomy questionnaire) were completed by 127 patients with severe haemophilia (<1% clotting activity), as well as four performance tests (button test, 50 metre walking test, timed-up-and-go test and figure-8 walking test). After removal of 15 non-informative items from the provisional HAL, three components within the questionnaire were identified (upper extremity activities, basic lower extremity activities and complex lower extremity activities). The internal consistency of these components was high (Cronbach's alpha = 0.93-0.95), as was internal consistency for the seven domains of the HAL (alpha = 0.61-0.96). The convergent validity of the HAL when compared to the other two questionnaires was good (r = 0.47-0.84). The construct validity of the HAL when compared to the four performance tests was generally lower (r = 0.23-0.77). The final version of the HAL has good internal consistency and convergent validity and gives the clinician insight into a patient's self-perceived ability to perform activities of daily life. It is likely that self-assessment instruments (questionnaires) and performance tests consider different concepts of functional health status and it is therefore recommended that both types are included when clinicians assess a patient's functional abilities.