Validity of performance scales for disability assessment in multiple sclerosis
Ruth Ann Marrie1*
and
Myla Goldman2
1 Department of Neurology, Cleveland Clinic, Cleveland, OH, USA
2 Department of Neurology, University of Virginia, Charlottesville, VA, USA
* To whom correspondence should be addressed.
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Abstract |
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Researchers increasingly use self-reported health status assessments, but these
require validation. Performance Scales (PS) is a self-report measure for multiple
sclerosis (MS)-associated disability, assessing mobility, bowel/bladder,
fatigue, sensory, vision, cognition, spasticity and hand function. The criterion
validity of the total PS score was established using the Expanded Disability Status
Scale (EDSS), but the construct and criterion validity of the individual subscales
have not been established. We assessed the criterion and construct validity of the
PS subscales. Forty-four patients with MS completed PS, and these criterion
measurements: neurological examination (EDSS), the Multiple Sclerosis Functional
Composite (MSFC), contrast acuity testing, and the Multiple Sclerosis Quality of
Life Inventory. We assessed criterion and construct validity with Spearman rank
correlations between PS subscales and the other measurements. PS correlated with the
MSFC (r = -0.58, P < 0.0001). The
mobility, hand, vision, fatigue and bladder subscales correlated with their
criterion measures (r = 0.59–0.77, P <
0.0001). The sensory subscale correlated weakly with the sensory functional system
score (r = -0.39, P = 0.01), and the
cognitive subscale did not correlate with the PASAT (r =
-0.17, P = 0.26). This study supports the criterion and
construct validity of PS overall, and its mobility, hand, vision, fatigue, and
bladder subscales. Further assessment of the cognitive, sensory and spasticity
subscales is needed. Multiple Sclerosis 2007; 13: 000–000. http://msj.sagepub.com
Key Words:
multiple sclerosis; validity; disability; performance scales; MSFC; self-report
