Reliability of the Sensory Organization Test over clinical administration time intervals of concussion assessment
Lee, Hyung Rock
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Evaluating postural stability using instrumented posturography is recommended as one of the integral assessments in the concussion test battery. Traditionally, linear mathematical measures have been used for assessing postural stability, but measures that can detect the underlying nonlinear control of balance (e.g., multiscale entropy [MSE]) may be more valid. However, practice effects may affect intra- and inter-day reliability. Therefore, the purposes of this study were to: a) evaluate the test-retest reliability of the NeuroCom Sensory Organization Test (SOT), using the SOT software’s ‘equilibrium scores’ and the complexity index (CI) of laboratory-generated MSE values; and b) assess the interday reliability of practice effects at clinically-relevant time intervals. Healthy, college-age subjects (N=92) were randomly divided into two testing-order groups: block and random. At all test sessions, the block group performed the three trials of each of the six sensory conditions in the same order, from least to most sensory challenging; the random group performed the conditions in a random order. All subjects performed the SOT three times on day 1 (20-minute break), and one time on days 45 and 50. CI was computed for each trial by integrating the MSE-scale values (N=2000, m=2, scales=2 to 20). Mixed-measures ANOVA and intraclass correlation coefficients were calculated (SPSS and R software). Major findings include a range of reliability from fair-to-good to excellent for CIs as well as ESs in the anterior-posterior direction for 10 out of 12 SOT conditions, and fair-to-good reliability for CIs in the medial-lateral direction. The results provided evidence of the clinically acceptable reliability of the SOT using CI scores for AP and ML directions, especially for the AP direction for which the highest reliability was reported. Practice effects were exhibited between the first and second test, as increased SOT scores for composite and visual equilibrium scores were displayed at the second test. However, no differences in the SOT scores were found between test-order groups. The findings support that clinicians should administer at least one preliminary SOT to obtain the best baseline score for concussion assessment, thereby eliminating potential practice effects that would affect balance scores obtained from multiple administrations of the SOT.