Clinical applicability and test-retest reliability of an external perturbation test of balance in stroke subjects.

We address the test-retest reliability and clinical applicability of an adapted external perturbation balance assessment, ie, the Postural Stress Test (PST). Repeated-measures were designed to assess the clinical features of a component of balance disorder in stroke. Twenty ambulatory stroke patients and 20 age-, gender-, height-, and weight-matched healthy control subjects participated in this study. Stroke patients were tested (using the adapted PST) on 4 separate days; matched control subjects were tested on one occasion. With the subject standing, backward perturbation forces were applied at the level of the center of gravity. Postural reactions to the test were scored in real-time and from videotape, from two different viewing angles, ie, 45 degrees and 90 degrees to the saggital plane. Scores (out of a maximal of 81) were ascertained using a 10-point subjective-observational scale. None of the control subjects fell during testing; four of the hemiplegic subjects fell. Subjects were protected from potential injury by a custom-designed safety harness system. For the hemiplegic subjects, intraclass correlation coefficients (ICCs), calculated as the reliability of any one occasion, ranged from 0.71 to 0.77, whereas those calculated as the reliability of the mean of the first two occasions ranged from 0.83 to 0.93. Although scores on the fourth occasion were significantly greater than those on the third occasion, both being significantly greater than those on the first and second test occasions (p < .05), differences were less than 5 points on the 81-point scale.(ABSTRACT TRUNCATED AT 250 WORDS)