Evaluation of the Multiple Sclerosis Walking Scale-12 (MSWS-12) in a Dutch sample: Application of item response theory

Abstract

Background:

The Multiple Sclerosis Walking Scale-12 (MSWS-12) measures walking ability from the patients’ perspective. We examined the quality of the MSWS-12 using an item response theory model, the graded response model (GRM).

Methods:

A total of 625 unique Dutch multiple sclerosis (MS) patients were included. After testing for unidimensionality, monotonicity, and absence of local dependence, a GRM was fit and item characteristics were assessed. Differential item functioning (DIF) for the variables gender, age, duration of MS, type of MS and severity of MS, reliability, total test information, and standard error of the trait level (θ) were investigated.

Results:

Confirmatory factor analysis showed a unidimensional structure of the 12 items of the scale, explaining 88% of the variance. Item 2 did not fit into the GRM model. Reliability was 0.93. Items 8 and 9 (of the 11 and 12 item version respectively) showed DIF on the variable severity, based on the Expanded Disability Status Scale (EDSS). However, the EDSS is strongly related to the content of both items.

Conclusion:

Our results confirm the good quality of the MSWS-12. The trait level (θ) scores and item parameters of both the 12- and 11-item versions were highly comparable, although we do not suggest to change the content of the MSWS-12.

Keywords

Multiple Sclerosis Walking Scale-12 (MSWS-12)multiple sclerosis walking ability item response theory (IRT)graded response model item fit differential item functioning psychometrics

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References

Hoang

Cameron

Gandevia

. et al. Neuropsychological, balance, and mobility risk factors for falls in people with multiple sclerosis: A prospective cohort study. Arch Phys Med Rehabil 2014; 95(3): 480–486.

Heesen

Bohm

Reich

. et al. Patient perception of bodily functions in multiple sclerosis: Gait and visual function are the most valuable. Mult Scler 2008; 14(7): 988–991.

Sutliff

. Contribution of impaired mobility to patient burden in multiple sclerosis. Curr Med Res Opin 2010; 26(1): 109–119.

Coenen

Cieza

Freeman

. et al. The development of ICF Core Sets for multiple sclerosis: Results of the International Consensus Conference. J Neurol 2011; 258(8): 1477–1488.

Kieseier

Pozzilli

. Assessing walking disability in multiple sclerosis. Mult Scler 2012; 18(7): 914–924.

Hobart

Riazi

Lamping

. et al. Measuring the impact of MS on walking ability: The 12-Item MS Walking Scale (MSWS-12). Neurology 2003; 60(1): 31–36.

Bethoux

Bennett

. Evaluating walking in patients with multiple sclerosis: Which assessment tools are useful in clinical practice? Int J MS Care 2011; 13(1): 4–14.

Baert

Freeman

Smedal

. et al. Responsiveness and clinically meaningful improvement, according to disability level, of five walking measures after rehabilitation in multiple sclerosis: A European multicenter study. Neurorehabil Neural Repair 2014; 28(7): 621–631.

Marangoni

Pavan

Tilbery

. Cross-cultural adaptation and validation of the 12-item Multiple Sclerosis Walking Scale (MSWS-12) for the Brazilian population. Arq Neuropsiquiatr 2012; 70(12): 922–928.

10.

Ansari

Naghdi

Mohammadi

. et al. Multiple Sclerosis Walking Scale-12, translation, adaptation and validation for the Persian language population. Gait Posture 2015; 41(2): 420–424.

11.

Edelen

Reeve

. Applying item response theory (IRT) modeling to questionnaire development, evaluation, and refinement. Qual Life Res 2007; 16(Suppl. 1): 5–18.

12.

Hays

Morales

Reise

. Item response theory and health outcomes measurement in the 21st century. Med Care 2000; 38(9 Suppl.): II28–II42.

13.

Embretson

Reise

. Item response theory for psychologists. Mahwah, NJ: Lawrence Erlbaum Associates, 2000.

14.

Reise

Haviland

. Item response theory and the measurement of clinical change. J Pers Assess 2005; 84(3): 228–238.

15.

Bentler

. Cutoff criteria for fit indexes in covariance structure analysis: Conventional criteria versus new alternatives. Struct Equ Modeling 1999; 6(1): 1–55.

16.

Kenny

. http://davidakenny.net/cm/fit.htm (2015, accessed 7 July 2015).

17.

Sijtsma

Molenaar

. Introduction to nonparametric item response theory. Thousand Oaks, CA: SAGE, 2002.

18.

Sijtsma

. On the use, the misuse, and the very limited usefulness of Cronbach’s alpha. Psychometrika 2009; 74(1): 107–120.

19.

Samejima

. Estimation of latent ability using a response pattern of graded scores. Richmond, VA: The Psychometric Society, 1969.

20.

Orlando

Thissen

. Likelihood-based item-fit indices for dichotomous item response theory models. Appl Psychol Meas 2000; 24(1): 50–64.

21.

Orlando

Thissen

. Further investigation of the performance of S–X2: An item fit index for use with dichotomous item response theory models. Appl Psychol Meas 2003; 27(4): 289–298.

22.

Mokkink

Knol

Van Nispen

RMA

. et al. Improving the quality and applicability of the Dutch scales of the Communication Profile for the Hearing Impaired using item response theory. J Speech Lang Hear Res 2010; 53: 556–571.

23.

Motl

Snook

. Confirmation and extension of the validity of the Multiple Sclerosis Walking Scale-12 (MSWS-12). J Neurol Sci 2008; 268(1–2): 69–73.

24.

Solaro

Trabucco

Signori

. et al. Italian validation of the 12-item multiple sclerosis walking scale. Mult Scler Int 2015; 2015: 540828.

25.

McGuigan

Hutchinson

. Confirming the validity and responsiveness of the Multiple Sclerosis Walking Scale-12 (MSWS-12). Neurology 2004; 62(11): 2103–2105.