Interpreting Change in Sport Concussion Assessment Tool-5th Edition (SCAT5) Scores in National Rugby League Women’s Premiership Players

Abstract

Background

The Sport Concussion Assessment Tool (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 have been published for the SCAT5, reliability data are 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 years, 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. Reliable change scores for the SCAT5 were developed in this study for use with professional women rugby league players. When evaluating post-injury SCAT5 scores, it can be helpful to consider both what the score means compared to normative reference values and compared to the athlete’s individual baseline scores.

Key Points

This is the first study to examine test-retest reliability of the SCAT5 in women’s rugby league.

In professional women’s rugby league, the one-year test-retest reliability coefficients of all SCAT5 subcomponents were low to moderate.

Although women athletes are unlikely to have identical scores on the SCAT5 subcomponents across two testing time points, large variations in scores, especially in cognitive testing (SAC) and the modified Balance Error Scoring System (mBESS), are uncommon.

Clinicians working in professional women’s rugby league could use the reliable change methodology and normative reference cut-offs, as part of their clinical formulation, when interpreting SCAT5 results following a suspected concussion.