Am J Occup Ther. 2003 Jul-Aug;57(4):389-95
Mathiowetz V.
Program in Occupational Therapy, Department of Physical Medicine &
Rehabilitation, University of Minnesota, MMC 388, 420 Delaware Street SE,
Minneapolis, Minnesota 55455, USA
OBJECTIVE:
The test-retest reliability and the convergent validity of the Fatigue Impact Scale (FIS) were evaluated using secondary data from 54 persons with multiple sclerosis (MS).
METHODS:
This reliability and validity study used FIS data from before and after two control periods to evaluate test-retest reliability.
Convergent validity of the FIS with the Fatigue Severity Scale and with subscales of the SF-36 Health Survey was evaluated using data collected before the first control period.
RESULTS:
No significant differences between before and after FIS measurements and intraclass correlation coefficients ranging from .68 to .85 indicate that the FIS has good test-retest reliability except for the physical subscale.
The expected moderate correlations between the FIS and several subscales of the SF-36 support its convergent validity.
In contrast, the unexpected low correlation between the FIS and Fatigue Severity Scale does not support convergent validity.
CONCLUSION:
The FIS has adequate reliability and validity and is recommended to evaluate the effectiveness of fatigue management interventions such as energy conservation education for persons with MS.