Return-to-Play after Concussion in American versus European Professional Soccer Players: A Comparative Short-Term Analysis of Performance and Longevity

Abstract

Objectives: Many studies have focused on the long-term impact of concussions in professional sports, but few have investigated short-term effects. This study examines concussion effects on individual players in the Major League Soccer (MLS) and English Premier League (EPL) by assessing 1) return-to-play (RTP) time, 2) career length, and 3) performance. Methods: Contracts, transactions, injury reports, and performance statistics from 2008-17 were obtained from the official MLS and EPL online publications. Players who sustained a concussion were compared with the 2008-17 non-concussed player pool. Career length was analyzed using Kaplan-Meier survival curves and athletes were stratified by player age, experience, and longevity. Player performance changes were evaluated between the years before versus after concussion. RTP and games missed were analyzed and compared. Results: Of the 1,784 eligible MLS and 2,001 eligible EPL players evaluated over the 10-year period, 102 MLS players sustained 165 concussions and 124 EPL players sustained 142 concussions resulting in injury protocol initiation. MLS players on average missed 7.5 games after a concussion, with 33.5 days missed, whereas EPL players on average missed 0.5 games after a concussion with 9.5 days missed, which was statistically different (p<0.001, p<0.0001). Performance was reduced at all non-goalie positions for goals and assists post-concussion for players in the MLS and in the EPL (p < 0.01). Concussed MLS players playing non-goalie positions scored 2.5 points/year less following a concussion and played in 20 fewer games/year on average. Concussed EPL players playing non-goalie positions scored 3.1 points/year less following a concussion and started in 5.8 fewer games/year on average. Concussed MLS and EPL goalies saw no significant change in performance, although EPL goalies played 3.2 additional games/year on average (p <0.05). The probability of playing a full season post-concussion was not significantly decreased compared with the non-concussed pool (p > 0.05) in both leagues Conclusion: This study investigating the short-term effects of concussion on professional soccer players demonstrates that performance is reduced for non-goalie players, without a significant difference in career longevity between concussed and non-concussed controls.