Performance-based tests in subjects with stroke: outcome scores, reliability and measurement errors

Objectives: To assess the intra-and inter-rater reliabilities and measurement errors of seven widely applied performance-based tests for stroke subjects (comfortable/maximal gait speeds and both stair ascending/descending cadences, as well as the Timed 'Up and Go' test) and to verify whether the use of different types of outcome scores (one trial, the means of two and three trials, and the best and the worst values of the three trials) affected the score values, as well as their reliability and measurement errors. Design: Intra- and inter-rater reliability study. Setting: Research laboratory. Subjects: Sixteen stroke subjects with a mean age of 52 +/- 17.9 years. Main measures: Seven performance-based tests, over two sessions, seven days apart, evaluated by two independent examiners. A third examiner recorded all data. One-way ANOVAs, intra-class correlation coefficients (ICCs) and percentages of the standard errors of measurement (SEM%) were used for analyses. Results: For all tests, similar results were found for all types of outcome scores (0.01 <= F <= 0.56; 0.34 <= p <= 0.00). For instance, at the comfortable gait speed, the means (SD) values for the first trial, the means of two and three trials and the best and worst of three trials were, respectively, 1.04 (0.25), 1.04(0.24), 1.05 (0.24), 1.10 (0.26), 1.02 (0.24) seconds. Significant and adequate values of intra- (0.75 <= ICC <= 0.96; p <= 0.002) and inter-rater (0.75 <= ICC <= 0.97; p <= 0.001) reliabilities were found for all tests and outcome scores. Measurement errors were considered low (5.01 <= SEM% <= 14.78) and were also similar between all outcome scores. Conclusions: For the seven tests, only one trial was necessary to provide consistent and reliable results regarding the functional performances of stroke subjects.