Prior Concussion History and Clinical Recovery After Sport-Related Concussion in High School Athletes.

Clinical recovery after sport-related concussion varies as a function of pre-injury and acute factors. Whether, or the extent to which, concussion history is associated with clinical outcome after sport-related concussion is uncertain, because research has produced mixed findings. The present study aimed to assess whether a history of previous concussions was associated with prolonged clinical recovery after a subsequent sport-related concussion. The sample comprised 780 adolescent student athletes (mean age = 16.3, standard deviation = 1.3 years; 56.8% boys, 43.2% girls) whose school participated in the Maine Concussion Management Initiative (MCMI). Survival analyses were used to compare recovery times among adolescents with a history of 0, 1, or ≥2 previous concussions after a subsequent sport-related concussion. The two primary outcomes of interest were the number of days to return to school and sports. There were no statistically significant differences in total time to return to school and sports, or the proportion of adolescents who returned to school and sports at most intervals (e.g., 7, 14, 28 days), between those with 0, 1, or ≥2 previous concussions. A greater proportion of adolescents, however, with a history of ≥2 previous concussions remained out of sports at 28 days compared with those with no previous concussions (23.5% vs. 12.7%; odds ratio [OR] = 2.10, 95% confidence interval [CI] 1.18-3.73). Having sustained prior concussions was not associated with time to return to school after a subsequent sport-related concussion. A greater proportion of adolescents, however, with two or more previous concussions experienced a prolonged return to sports. Further research is warranted to identify risk factors for worse outcomes among the subset of adolescents with a history of multiple previous concussions who experience prolonged recoveries.