Annual baseline drift in professional rugby league players

Objective Annual baseline testing within professional Rugby League has been mandatory since 2004. The question, do annual baselines drift over time or as a result of a concussion in rugby league players is unanswered. If they do drift, what is the magnitude and in what tasks and is this correlated to associated concussions. The study evaluated if baselines drift over time and if so is this related to concussive injury or accumulating injury. Design Retrospective study Method Participant players were those who held a professional contract between the 2006–2012 season. It is mandatory to provide an annual baseline test using CogSport and following any diagnosed concussion, with full symptom resolution, a valid return to play test. Concussion test data was provided by CogState Australia from tests performed over 7 seasons. Results Over the 7-year period 4762 players suffered 470 concussions (2.65/1000 hours, 95% Confidence Interval 2.4 to 2.9). Identification increased with previous concussion (0.017, 0.001 to 0.029, P=0.05) but not season. One Back Memory decreased with concussion (−.05 to −.05, P=0.001). One Card Learning decreased with previous concussion (−0.041, −0.049 to −0.34, P=0.001) and season (−0.006, −0.007 to −0.005, P=0.001). Conclusions Over seven seasons, item scores within the CogSport test varied as a function of previous concussion and time. Individual items within the CogSport test were influenced by differing factors and further examination of the individual items is warranted. Competing interests Lisa Hodgson, Conor Gissane, P Walker – None. Paul Maruff – Full time employee of CogState D Darby – Former Founder and Director of Cogstate