Concussion symptom clusters and changes in symptom reporting and severity following multiple concussions in male...

Symptom reporting remains an important part of the diagnosis and management of concussion. Understanding the patterns of symptoms and symptom clusters in athletes with multiple concussions may be clinically valuable. The purpose of this study was to characterise acute symptom reporting in players with multiple concussions.

National Rugby League (NRL) players who have sustained multiple concussions between the 2017 and 2022 seasons were included in the study. Data included the symptoms reported on the Sport Concussion Assessment Tool - 5th Edition (SCAT5) during the Head Injury Assessment by players who were subsequently diagnosed with concussion. K-means clustering with k = 6 centres was performed on symptom severity data. Each concussion episode was assigned to one symptom cluster based on the athlete's symptom presentation. Transitions between symptom clusters from initial to subsequent concussions were visualised using a Sankey plot.

There were 120 players who sustained more than one concussion, including 75 players with two, 23 with three, 15 with four, and 7 players with five or more medically diagnosed concussions. The average duration between concussions was 441 days (SD: 332; Md: 370; range: 11-1435 days). There were 6 different symptom clusters identified. Players were commonly found to transition between clusters for subsequent concussions, most commonly the 'Asymptomatic' cluster. There was no relationship found for days between concussions and symptom count or severity. Symptom severity, but not symptom count, was associated with days until medical clearance.

Acute symptom reporting varies with subsequent concussions, making it difficult to predict post-concussion symptoms in individual players. Acute symptom severity was associated with time to medical clearance, whereas the number of concussions in the preceding two years was not.