Psychometric properties of the SDM-Q-9 questionnaire for shared decision-making in multiple sclerosis: item response theory modelling and confirmatory factor analysis

Abstract

BackgroundShared 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.MethodsA 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.ResultsA 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.ConclusionsThe SDM-Q-9 presents appropriate psychometric properties and is therefore useful for assessing different aspects of shared decision-making in patients with multiple sclerosis.

Does Shared Decision Making Actually Occur in the Emergency Department? Looking at It from the Patients’ Perspective

“…The SDM‐Q‐9 was developed by taking the theoretical key steps of SDM and translating them into actionable items . Considerable refinements led to the final nine‐item tool, which has since undergone psychometric testing in different populations, such as oncology, neurology, and behavioral health, with generally favorable properties (for example, in the oncology population, total sum scores derived from the general factor showed good reliability in terms of omega coefficient = 0.90) …”

Unmet needs, burden of treatment, and patient engagement in multiple sclerosis: A combined perspective from the MS in the 21st Century Steering Group

“…Critically, adding the perspective of patients to that of their HCPs is essential for optimising care (Golla et al, 2012). While a shared decision-making approach in patient-centred care has been the focus of recent publications in MS (Ballesteros et al, 2017;Col et al, 2017;Colligan et al, 2017), it is still not as well developed as it is in other therapeutic areas, such as in the community of people living with human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS).…”

“…In line with the early views of HIV/AIDS patients and advocates, both PwMS and HCPs believe that collaborative interactions are required to fully understand and address the complex issues involved in MS, and to improve future care; a collective patient-HCP voice is a positive and powerful one. Although a patient-centred approach in MS has started to emerge in the literature (Ballesteros et al, 2017;Col et al, 2017;Colligan et al, 2017) there is still a lack of recognition of the importance of a shared PwMS-HCP perspective in MS care (Tintoré et al, 2016).…”

Psychometric properties of the Arabic version of the 9-item Shared Decision-Making Questionnaire: the entire process from translation to validation

“…A total of 40 instruments were included, in this review, and results on the best evidence synthesis were inconclusive or unknown for 50% or more for the measurement psychometric properties mainly due to poor methods 6. We chose the 9-item Shared Decision Making Questionnaire (SDM-Q-9), as we wanted to have a patient-reported SDM measure in Arabic that has both good psychometric properties and that has been widely used 21. The SDM-Q-9 has been translated into more languages than any other SDM measure and has been used in a large amount of studies 22 23.…”