Article

OBJECTIVE: To examine the validity and sensitivity to change of the Multiple
Sclerosis-Fatigue Self-Efficacy scale. DESIGN: A validation study nested within a
randomized controlled trial. SETTING: Community setting. PARTICIPANTS: Adults
with a clinically definite diagnosis of multiple sclerosis and significant
fatigue taking part in a randomized controlled trial evaluating a group-based
fatigue management programme (FACETS) for people with multiple sclerosis (N=164).
MAIN MEASURES: The 9-item Multiple Sclerosis-Fatigue Self-Efficacy scale was
completed at baseline, 1-, 4- and 12 months post intervention. Validity, internal
consistency and sensitivity to change were examined using classical test theory
and Rasch analysis. RESULTS: Item 3 was unanswered by 6% of respondents as they
did not know any other people with multiple sclerosis; remaining analyses were
carried out with this item deleted. All response choices were utilised, no floor
or ceiling effects were evident and there were few missing responses. Cronbach's
alphas were high (baseline, 0.89; follow-up 1, 0.93; follow-up 2, 0.94; follow-up
3, 0.90). The Multiple Sclerosis-Fatigue Self-Efficacy scale (8-item)
demonstrated good sensitivity to change following attendance of the FACETS
programme (within participant effect sizes 0.66 and 0.69 and 0.54 at 1, 4, and 12
months follow-up). Principal Components Analysis yielded one component. In the
Rasch analysis two items with disordered thresholds were rescored. Item 8
displayed differential item functioning by disability and was combined into a
testlet with item 4, resulting in a unidimensional scale.
The sample was well
targeted to the scale. CONCLUSION: At a scale level the Multiple
Sclerosis-Fatigue Self-Efficacy scale is internally valid and has good
sensitivity to change.
CI - (c) The Author(s) 2014.

Langue : ANGLAIS