Objective
Fatigue is a common complaint amongst youth and adults with Cerebral Palsy (CP). It is multi-faceted and can affect many aspects of an individual’s life. In order to support youth and adults with CP in managing their fatigue, it is important for clinicians to have appropriate assessment tools. The objective of this study was to compare fatigue self-report assessment tools in a group of adults with CP to guide clinicians in their future practice.
Participants and Methods
Thirty youth and adults with CP were assessed with Danish versions of the Fatigue Impact and Severity Self-Assessment (FISSA) questionnaire (Brunton, 2017), the Modified Mental Fatigue Scale (m-MFS) (Bergqvist, 2019), and the Multidimensional Fatigue Inventory (MFI-20) (Smets et al., 1995). The questionnaires were designed for different populations with the m-MFS and the FISSA designed specifically for a CP population and the MFI-20 as a generic tool to assess fatigue in a wide range of patient and non-patient populations. While the m-MFS focuses on mental fatigue and the FISSA on physical fatigue, the MFI-20 was designed to assess five dimensions: General Fatigue, Physical Fatigue, Reduced Activity, Reduced Motivation, and Mental Fatigue. The psychometric properties of each questionnaire were investigated. Rank order and classification models were compared across questionnaires. In addition, associations between fatigue severity and background variables were analyzed.
Results
Investigations of psychometric properties revealed that while item statistics for the FISSA Impact Scale and the m-MFS were generally satisfactory, there was inadequate internal consistency for the Reduced Motivation and the Physical Fatigue subscale of the MFI-20. Significant positive inter-correlations were found across the core scales of the questionnaires suggesting that they measure a similar construct. However, participants were frequently ranked differently with the three scales, suggesting that they capture distinct aspects of fatigue. The MFI-20 and the m-MFS are the only tools that provide pathological cut-off scores and we found that there was considerable likelihood for a participant as being classified as having pathological fatigue with one tool and not the other. Investigations of construct validity across tools revealed issues related to the conceptualization of physical fatigue. We did not find a statistical difference in fatigue severity across GMFCS levels and found no significant association between age and fatigue severity.
Conclusions
The study has demonstrated that choices made by clinicians with regards to which fatigue self-report assessment tools they use, can have important implications on the conclusions that are likely to be made with regards to the extent to which an individual is considered to be affected by fatigue. Based on the findings, it can be argued that pathological fatigue in CP should be diagnosed on the basis of formal diagnostic criteria rather than based on the score on single self-report fatigue tools.