Análise Psicométrica da Versão Brasileira da Pittsburgh Fatigability Scale (PFS-Brasil)

Abstract

Introduction: Instruments with appropriate psychometric properties are essential for ensuring the quality of assessments and reassessments in clinical practice, guiding decision-making regarding rehabilitation procedures. The Pittsburgh Fatigability Scale, originally published in English, is the only validated scale for measuring perceived fatigability in older adults. Considering the importance of this tool, it is necessary to validate its translated version into Portuguese and adapt it to the specificities of the Brazilian context. Objective: To validate the Pittsburgh Fatigability Scale Brazilian Portuguese version (PFS-Brasil) by evaluating its validity in relation to measures of physical activity, physical performance, and cognitive performance. Methodology: The scale and physical and cognitive performance tests were used to assess 121 healthy older adults residing in the community. We conducted statistical analyses of the physical and mental subscales of the PFS-Brasil, utilizing the intraclass correlation coefficient (ICC) for reliability analysis, Cronbach's alpha for internal consistency evaluation, and Spearman's correlation for convergent validity. Furthermore, we examined agreement analysis and floor and ceiling effects. The Statistical Package for Social Sciences 25.0 was used for data analysis. Results: The analyses indicated that the physical and mental subscales exhibit satisfactory test-retest reliability, with ICC values for the physical subscale (0.84; 95% CI: 0.80-0.88) and the mental subscale (0.83; 95% CI: 0.78-0.87), in addition to high internal consistency (α = 0.84 and 0.82, respectively). These values are indicative of good inter-rater reliability, revealing a low probability of random and systematic error. Bland-Altman plots demonstrated good agreement for both subscales of the PFS-Brasil. For convergent validity, the higher physical score showed a moderate association, and the higher mental score showed a weak association with lower physical performance (6-minute walk tests and the Short Physical Performance Battery (SPPB) and lower levels of physical activity (International Physical Activity Questionnaire – IPAQ). Regarding cognitive performance, there was a weak association between the higher mental score and the average accuracy on the flanker test. No ceiling effects were observed in both subscales; however, the mental subscale exhibited a floor effect (n = 24%). Conclusion: This study demonstrated that the Brazilian version of the Pittsburgh Fatigability Scale is a valid, consistent, and reliable instrument for assessing perceived fatigability in older adults.