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Brogårdh C1,2, Jonasson SB1, Lexell J1,3
1Lund University, Dept of Health Sciences, Lund, Sweden, 2Skåne University Hospital, Dept of Neurology and Rehabilitation Medicine, Lund, Sweden, 3Uppsala University, Dept of Neuroscience, Rehabilitation Medicine, Uppsala, Sweden
Background: Many years after an acute poliomyelitis infection, persons may experience new or increased symptoms referred to as late effects of polio (LEoP) or postpolio syndrome. Fatigue is often reported as the most disabling symptoms and could be a long-lasting problem among these persons. Fatigue is defined as “an overwhelming sense of tiredness, lack of energy and feeling of exhaustion”, and is shown to be negatively associated with mobility and life satisfaction. Several rating scales are used to assess fatigue and the three most commonly in persons with LEoP are the Fatigue Severity Scale (FSS), the Fatigue Impact Scale (FIS) and the Multidimensional Fatigue Inventory (MFI-20). To use psychometrically sound rating scales in clinical settings and in research is important to allow accurate assessments of fatigue. Even though these three rating scales are commonly used in clinical work and research, a comprehensive analysis of their psychometric properties is lacking.
Purpose: To evaluate the psychometric properties of the FSS, the FIS and the MFI-20 in persons with LEoP. More specifically, we explored the scales' data completeness, scaling assumptions, targeting, reliability and convergent validity.
Methods: A postal survey including FSS, FIS and MFI-20 was administered to 77 persons with LEoP. Responders received a second survey after three weeks to enable test-retest reliability analyses.
Results: Sixty-one persons (mean age 68 years, 54% women) responded to the survey (response rate 79%). Data quality of the rating scales was high (0-0.5% missing item responses), the corrected item-total correlations exceeded 0.4 and the scales showed very little floor or ceiling effects (0-6.6%). All scales had acceptable reliability (Cronbach's alpha ≥ 0.95) and test-retest reliability (Intraclass Correlation Coefficient, ICC ≥ 0.80). The Standard Error of Measurement was 7-10% of the possible scoring range, and the Smallest Detectable Difference was 20-28% of the possible scoring range. All three scales were highly correlated (Spearman's correlation coefficient, rs = 0.79 - 0.80; p 0.001).
Conclusion(s): The FSS, FIS and MFI-20 have sound psychometric properties in terms of data completeness, scaling assumptions, targeting, reliability and convergent validity. This indicates that these three rating scales can be used to assess fatigue in persons with LEoP. As FSS has fewer items and therefore is less time consuming it may be the preferred scale. However, the choice of scale depends on the research question and the design of the study.
Implications: This study shows that all three rating scales are psychometrically sound and can be used in rehabilitation of persons with fatigue and late effects of polio.
Keywords: Fatigue;, Postpoliomyelitis syndrome;, Psychometrics;
Funding acknowledgements: The study was funded by Stiftelsen för bistånd åt rörelsehindrade i Skåne.
Purpose: To evaluate the psychometric properties of the FSS, the FIS and the MFI-20 in persons with LEoP. More specifically, we explored the scales' data completeness, scaling assumptions, targeting, reliability and convergent validity.
Methods: A postal survey including FSS, FIS and MFI-20 was administered to 77 persons with LEoP. Responders received a second survey after three weeks to enable test-retest reliability analyses.
Results: Sixty-one persons (mean age 68 years, 54% women) responded to the survey (response rate 79%). Data quality of the rating scales was high (0-0.5% missing item responses), the corrected item-total correlations exceeded 0.4 and the scales showed very little floor or ceiling effects (0-6.6%). All scales had acceptable reliability (Cronbach's alpha ≥ 0.95) and test-retest reliability (Intraclass Correlation Coefficient, ICC ≥ 0.80). The Standard Error of Measurement was 7-10% of the possible scoring range, and the Smallest Detectable Difference was 20-28% of the possible scoring range. All three scales were highly correlated (Spearman's correlation coefficient, rs = 0.79 - 0.80; p 0.001).
Conclusion(s): The FSS, FIS and MFI-20 have sound psychometric properties in terms of data completeness, scaling assumptions, targeting, reliability and convergent validity. This indicates that these three rating scales can be used to assess fatigue in persons with LEoP. As FSS has fewer items and therefore is less time consuming it may be the preferred scale. However, the choice of scale depends on the research question and the design of the study.
Implications: This study shows that all three rating scales are psychometrically sound and can be used in rehabilitation of persons with fatigue and late effects of polio.
Keywords: Fatigue;, Postpoliomyelitis syndrome;, Psychometrics;
Funding acknowledgements: The study was funded by Stiftelsen för bistånd åt rörelsehindrade i Skåne.
Topic: Neurology; Disability & rehabilitation
Ethics approval required: Yes
Institution: Lund University
Ethics committee: Regional Ethical Review Board, Lund, Sweden
Ethics number: Dnr 2013/380
All authors, affiliations and abstracts have been published as submitted.
