Viability of a MSQOL-54 general health-related quality of life score using bifactor model

Abstract

Background MSQOL-54 is a multidimensional, widely-used, health-related quality of life (HRQOL) instrument specific for multiple sclerosis (MS). Findings from the validation study suggested that the two MSQOL-54 composite scores are correlated. Given this correlation, it could be assumed that a unique total score of HRQOL may be calculated, with the advantage to provide key stakeholders with a single overall HRQOL score. We aimed to assess how well the bifactor model could account for the MSQOL-54 structure, in order to verify whether a total HRQOL score can be calculated. Methods A large international database (3669 MS patients) was used. By means of confirmatory factor analysis, we estimated a bifactor model in which every item loads onto both a general factor and a group factor. Fit of the bifactor model was compared to that of single and two second-order factor models by means of Akaike information and Bayesian information criteria reduction. Reliability of the total and subscale scores was evaluated with Mc Donald’s coefficients (omega, and omega hierarchical). Results The bifactor model outperformed the two second-order factor models in all the statistics. All items loaded satisfactorily (≥ 0.40) on the general HRQOL factor, except the sexual function items. Omega coefficients for total score were very satisfactory (0.98 and 0.87). Omega hierarchical for subscales ranged between 0.22 to 0.57, except for the sexual function (0.70). Conclusions The bifactor model is particularly useful when it is intended to acknowledge multidimensionality and at the same time take account of a single general construct, as the HRQOL related to MS. The total raw score can be used as an estimate of the general HRQOL latent score.

Applying multidimensional computerized adaptive testing to the MSQOL-54: a simulation study

“…In a previous study conducted in MS [ 37 ], we found that a bifactor model fit the data well, suggesting that a unidimensional HRQOL score can be computed using the MSQOL-54. By definition, items in the bifactor model load on a general factor and on one group factor only.…”

“…The overall HRQOL score could be used in clinical practice to provide health professionals and MS patients with feedback on current functioning [ 37 ]. Also, it could be useful to identify patient subgroups—with different levels of disability as well as disease forms—in order to deliver personalized interventions addressing, for example, resilience or self-efficacy.…”

MultiSCRIPT-Cycle 1- A Pragmatic trial embedded within the Swiss Multiple Sclerosis Cohort (SMSC) on neurofilament light chain monitoring to inform personalized treatment decisions in Multiple Sclerosis: a study protocol for a randomized clinical trial

“…MSQoL-54 is a structured self-reported questionnaire including 54 items generating 12 subscales with two summary scores, the physical health composite summary and the mental health composite summary (28). For the primary outcome, we will use the sum of both composite summaries as a total score (30).…”

The psychometric properties of the Persian version of the Multiple Sclerosis Self‐Management Scale‐Revised: A cross‐sectional methodological study

“…The 4-dimension MSSS measures patients' ability to manage their conditions and overcome their challenges 16 and the 12-dimension MSQOL-54 measures patients' physical and mental health. 17 These instruments are not SM-specific and do not cover all aspects of SM.…”

“…Examples of these instruments are the Multiple Sclerosis Self‐Efficacy Scale (MSSS) ‎‎and the Multiple Sclerosis Quality of Life‐54 (MSQOL‐54) scale. The 4‐‎dimension MSSS measures patients' ability to manage their conditions and overcome ‎their challenges 16 and the 12‐dimension MSQOL‐54 measures patients' physical ‎and mental health 17 . These instruments are not SM‐specific and do not cover all aspects of SM.…”