Measuring fatigue four years after stroke: a bi-factor analysis of the Norwegian Chalder Fatigue Questionnaire
摘要
Post-stroke fatigue (PSF) is a persistent and debilitating condition. Assessing its characteristics and severity accurately is important, but the suitability of existing fatigue instruments for use in stroke populations is uncertain. The Chalder Fatigue Questionnaire (CFQ) is a widely used generic measure capturing both mental and physical fatigue, but the dimensionality of the 11-item CFQ is debated. The objective of this study was to examine the best-fitting model for the CFQ and evaluate whether the addition of latent specific factors for the physical and mental items provided meaningful information beyond the latent general fatigue score.
MethodsWe examined three competing measurement model of the CFQ – unidimensional, correlated two-factor (physical and mental fatigue) and a bi-factor model in a sample of 144 individuals at 4 years post-stroke. Furthermore, we investigated how other criterion-related variables correlated with the estimated CFQ factor scores compared with the simple CFQ.
ResultsThe bi-factor measurement model had best fit. Partial correlation analyses indicated that a simple overall fatigue score aligns relatively well with the estimated general factor score, as does the physical sum score. This indicates that separate physical and mental sum scores provide no additional value, whereas their estimated latent specific factors contribute more information. Men reported less fatigue, and except for gender most of the demographic variables were not significantly correlated with the CFQ variables.
ConclusionDespite best psychometric support for a bi-factor measurement model, a simple overall sum score may be used to assess fatigue severity satisfactorily. While separate physical and mental factors provide noteworthy nuance, their contribution is in practice limited. Future research should consider refining the mental fatigue items if a more precise assessment or a more nuanced clinical applicability of the physical-mental separation following stroke is needed.