Interpreting change on the Sport Concussion Assessment Tool-5th Edition (SCAT5) in National Rugby League Women’s players

Abstract

Background The SCAT is a multimodal, evidence-based tool designed for repeat administration at baseline, pre-season and/ or for post-injury assessments, following a sport related concussion. Repeat administration of concussion assessment tools requires clinicians to understand the instrument’s stability and test-retest reliability. Typically, clinicians compare post-injury scores with baseline test results in order to determine whether a clinically significant change has occurred. The National Rugby League Women’s (NRLW) Premiership was created in 2018, with a concussion management process requiring annual pre-season baseline medical assessments of players using the Sport Concussion Assessment Concussion Tool-5th Edition (SCAT5). Although baseline normative data has been published for the SCAT5, reliability data is limited in women. The purpose of this study was to examine the one-year test-retest reliability of the SCAT5 component scores, and to develop reliable change indices, for the women’s league. Results Participants were 63 NRLW players (mean age = 26.9, SD = 5.5) from the 2018–2019 and 2019–2020 seasons. Team medical staff conducted the baseline SCAT5 assessments each year. Test-retest reliability estimates for each of the SCAT5 components were low to moderate (ICCs = 0.28–0.57). The following change scores, reflecting worsening, occurred in 20% or fewer of the sample: +3 symptom number, + 4 symptom severity, and − 2 on the Standardized Assessment of Concussion total score. A change of + 2 total modified Balance Error Scoring System errors occurred in fewer than 10% of the NRLW players between the test and retest. Conclusion SCAT5 scores had low to moderate test-retest reliability across a one-year period. When evaluating the likelihood that a change in a SCAT5 score is reliable and clinically meaningful it is important for clinicians working with professional women’s rugby league players to consider what a change in score means compared to normative reference values and individual baseline scores. Reliable change cutoff scores could be used to determine the magnitude of change after a suspected concussion.