Development and validation of a new questionnaire for the assessment of subjective physical performance in adult patients with haemophilia--the HEP-Test-Q.

Specific research studies for the investigation of physical performance in haemophilic patients are rare. However, these instruments become increasingly more important to evaluate therapeutic treatments. Within the frame of the Haemophilia & Exercise Project (HEP), a new questionnaire, namely HEP-Test-Q, has been developed for the assessment of subjective physical performance in haemophilic adults. In this article, the development and validation of the HEP-Test-Q is described. The development consisted of different phases including item collection, pilot testing and field testing. The preliminary version was pilot-tested in 24 German HEP-participants. Following evaluation and preliminary psychometric analysis, the HEP-Test-Q was revised. The final version consists of 25 items pertaining to the domains 'mobility', 'strength & coordination', 'endurance' and 'body perception', which was administered to 43 German haemophilic patients (43.8 +/- 11.2 years). Psychometric analysis included reliability and validity testing. Convergent validity was tested correlating the HEP-Test-Q with SF-36, Haem-A-QoL, HAL and the Orthopaedic Joint Score. Discriminant validity tested different clinical subgroups. Patients accepted the questionnaire and found it easy to fill in. Psychometric testing revealed good values for reliability in terms of internal consistency (Cronbach's alpha = 0.96) and test-retest reliability (r = 0.90) as well as for convergent validity correlating highly with Haem-A-QoL, HAL and SF-36. Discriminant validity testing showed significant differences for age, hepatitis A and hepatitis B and the number of target joints. HEP-Test-Q is a short and well-accepted questionnaire, assessing subjective physical performance of haemophiliacs, which might be combined with objective assessments to reveal aspects, which cannot be measured objectively, such as body perception.