Test-retest, intra- and inter-rater reliability of the reactive balance test in patients with chronic ankle instability

Introduction: Chronic ankle instability (CAI) affects 40-45% of those who have had an ankle sprain and leads to recurrent episodes of the ankle "giving way" and neuromuscular deficits.1 Clinicians use functional performance tests (FPTs) like the star excursion balance test (SEBT) and the Y-balance test (YBT) to identify those at risk of (re)injury and make better-informed return to sport (RTS) decisions.2,3 However, these tests are limited in on-field sports contexts. To address this, the reactive balance test (RBT) was developed.4,5 This study aimed to determine the reliability of the RBT in patients with CAI. Methods: Forty-three eligible patients were screened on the IAC inclusion criteria for CAI. Patients visited the lab three times for familiarisation and two experimental trials during which they performed the YBT and RBT on both legs. The test procedures and protocol were identical to the study of Tassignon et al. The duration and range of the test-retest time frame was chosen to reflect a clinically relevant period and lasted 22 (± 10) days on average. Three raters independently rated the different types of reliability by scoring the RBT outcome measures: accuracy and visuomotor response time (VMRT). Results: Twenty-seven patients with CAI were included in this study. The ICC measures for the test-retest reliability were similar for accuracy (0.609) and VMRT (0.594). Intra-rater reliability had high correlations and ICCs for accuracy (r=0.816, ICC=0.815) and VMRT (r=0.802, ICC=0.800). Inter-rater reliability had a higher ICC for VMRT (0.868) than for accuracy (0.690). Conclusion: Test-retest reliability was moderate, intra-rater reliability was good, and inter-rater reliability showed moderate reliability for accuracy and good reliability for VMRT. The data indicates the VMRT performance was more robust than the accuracy measure across the trials. When the Limits of agreement were compared with the minimal detectable change, the data indicates the RBT is more precise and sensitive to changes than the raters' score. Additionally, the RBT shows robust standard error of measurement and mean difference measures.