Inter- and Intra-Tester Reliability of Postural Stability Tests in Patients With Whiplash-Associated Disorder

Our study aimed to examine the inter- and intra-tester reliability of postural balance tests in patients with whiplash-associated disorder (WAD).

Fifteen adults with chronic WAD performed 7 different postural balance tests using a static force platform: in the neutral head position (neutral test), gaze rotated 20° (left and right), head rotated 20° (left and right), and neck torsioned 20° (left and right) positions. Inter- and intra-tester reliability were assessed for both individual tests and the differences between the neutral test and each test variant in sway velocity (mm/s) and velocity moment (mm²/s) parameters. This assessment utilized intra- and interclass correlation, mean differences of 2 measurements (paired t-test or Wilcoxon signed-rank test), the coefficient of within-subject variance, and the 95% percentile.

Overall results showed at least a strong (≥0.70) correlation between the 2 testers and the tester's 2 test sessions in the individual tests. Furthermore, the average results did not mainly differ between testers and test sessions, and no wide variability of results was noticeable, indicating that the results can be considered clinically meaningful. However, the correlations of the between-test differences primarily ranged from negligible to moderate, leaving the results clinically insignificant.

The results of this study suggest that individual postural balance tests yield clinically reliable results for patients with WAD. However, caution is warranted when assessing the difference between balance test variations. It is not yet known whether these tests can distinguish between different study groups and whether they are reliable in assessing different sensory systems.