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Título:
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Psychometric properties of the SDM-Q-9 questionnaire for shared decision-making in multiple sclerosis: item response theory modelling and confirmatory factor analysis
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Autor/a:
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Ballesteros, Javier; Moral, Ester; Brieva Ruiz, Luis; Ruiz-Beato, Elena; Prefasi, Daniel; Maurino, Jorge
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Notas:
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Background: Shared decision-making is a cornerstone of patient-centred care. The 9-item Shared Decision-Making
Questionnaire (SDM-Q-9) is a brief self-assessment tool for measuring patients’ perceived level of involvement in
decision-making related to their own treatment and care. Information related to the psychometric properties of the
SDM-Q-9 for multiple sclerosis (MS) patients is limited. The objective of this study was to assess the performance of
the items composing the SDM-Q-9 and its dimensional structure in patients with relapsing-remitting MS.
Methods: A non-interventional, cross-sectional study in adult patients with relapsing-remitting MS was conducted
in 17 MS units throughout Spain. A nonparametric item response theory (IRT) analysis was used to assess the latent
construct and dimensional structure underlying the observed responses. A parametric IRT model, General Partial
Credit Model, was fitted to obtain estimates of the relationship between the latent construct and item
characteristics. The unidimensionality of the SDM-Q-9 instrument was assessed by confirmatory factor analysis.
Results: A total of 221 patients were studied (mean age = 42.1 ± 9.9 years, 68.3% female). Median Expanded
Disability Status Scale score was 2.5 ± 1.5. Most patients reported taking part in each step of the decision-making
process. Internal reliability of the instrument was high (Cronbach’s α = 0.91) and the overall scale scalability score
was 0.57, indicative of a strong scale. All items, except for the item 1, showed scalability indices higher than 0.30.
Four items (items 6 through to 9) conveyed more than half of the SDM-Q-9 overall information (67.3%). The
SDM-Q-9 was a good fit for a unidimensional latent structure (comparative fit index = 0.98, root-mean-square error
of approximation = 0.07). All freely estimated parameters were statistically significant (P < 0.001). All items presented
standardized parameter estimates with salient loadings (>0.40) with the exception of item 1 which presented the
lowest loading (0.26). Items 6 through to 8 were the most relevant items for shared decision-making.
Conclusions: The SDM-Q-9 presents appropriate psychometric properties and is therefore useful for assessing
different aspects of shared decision-making in patients with multiple sclerosis.
The study was funded by Roche Farma SA, Spain |
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Materia(s):
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-SDM-Q-9
-Shared decision-making
-Multiple sclerosis
-Psychometrics
-Patient involvement |
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Derechos:
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cc-by (c) Ballesteros et al., 2017
http://creativecommons.org/licenses/by/4.0/
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Tipo de documento:
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article
publishedVersion |
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Editor:
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BioMed Central
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Compartir:
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