Reliability and internal validity of the michigan hand questionnaire.

BACKGROUND: The Michigan Hand Outcomes Questionnaire (MHQ) remains one of very few to be based on validated and systematic methods in its creation. However, test-retest reliability and internal validity have not been appropriately investigated in any other English-speaking population outside the original development sample. The objective of this study is to examine the reliability and internal validity of the MHQ in a Canadian population.
METHODS: All patients with a clinical hand problem but no hand immobilization who attended our Plastic Surgery Clinic were invited to participate in this study. Patients were asked to complete the MHQ, and then contacted to arrange for completion of the MHQ a second time. Internal validity was estimated using Cronbach alpha. Reliability was estimated using the method of Bland and Altman, and intraclass correlation coefficients. Correlation analysis between score differences and time between tests was performed.
RESULTS: Full versions of the MHQ were completed by 116 participants on their initial visit, while only 77 participants completed a second MHQ. Cronbach alpha ranged from 0.84 to 0.95 for the MHQ subscales. Intraclass-correlation coefficients ranged from 0.71 to 0.84 for the subscales. The magnitude of the limits of agreement for the subscales ranged from 13.8 to 26.2. The difference in scores between the first and second tests was not related to the time between tests.
CONCLUSION: The high values of Cronbach alpha indicate high internal validity, but that there may be redundancy between items in the MHQ, which could be eliminated without losing information. Reliability of the MHQ is considered moderate. The limits of agreement are considered wide, indicating potential issues with respect to interpretation of a change in score between 2 administrations of the MHQ.