Psychometric properties of the performance fatigue index in people with stroke

The performance fatigue index provides objective measures for assessing the impact of fatigue on performance and it may be utilized for monitoring functional outcomes in individuals with stroke; however, its psychometric properties have been minimally studied in this population.

To examine the test-retest reliability and agreement; known-group validity of the performance fatigue index; and its correlations with self-perceived fatigue, depressive symptoms, sleep quality, and reintegration to normal living in people with stroke.

Participants with and without stroke completed a 6-minute walk test for calculating the performance fatigue index. Participants with stroke also completed the Fatigue Assessment Scale, the Geriatric Depression Scale, the Pittsburgh Sleep Quality Index, and the Reintegration to Normal Living Index. The intra-class correlation coefficient, standard error of measurement, minimal detectable change, and known group validity of the performance fatigue index were determined. Spearman's correlation was used to examine the relationships between the index and other variables.

The intra-class correlation coefficient of the performance fatigue index was 0.99, the standard error of measurement was 0.53 and the minimal detectable change was 1.46. The performance fatigue index could be used to differentiate individuals with stroke from those without stroke. It significantly correlated with self-perceived physical fatigue subscore (r_s = 0.29, p = .034) and reintegration to normal living (r_s = -0.34, p = .012) but not correlated with self-perceived mental fatigue subscore, depressive symptoms, or sleep quality.

The performance fatigue index is reliable and valid in assessing and monitoring post-stroke physical fatigue in clinical and research settings.