Byline: AndrÈ¨e-Anne Ledoux, Children's Hospital of Eastern Ontario Research Institute, Ottawa, Ontario, Canada (Dr Ledoux, Tang, Osmond, and Zemek and Ms Healey); Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada (Dr Ledoux); Department of Pediatrics, Montreal Children's Hospital, McGill University Health Center, Montreal, Quebec, Canada (Dr Gagnon); School of Physical and Occupational Therapy, Faculty of Medicine, McGill University, Montreal, Quebec, Canada (Dr Gagnon); Department of Pediatrics, Children's Hospital of Eastern Ontario, University of Ottawa, Ottawa, Ontario, Canada (Drs Osmond and Zemek); Department of Psychology, Alberta Children's Hospital Research Institute, and Hotchkiss Brain Institute, University of Calgary, Alberta, Canada (Dr Yeates); and Division of Pediatric Neuropsychology, Children's National Hospital, Rockville, Maryland (Dr Gioia).; Ken Tang; Isabelle Gagnon; Martin H. Osmond; Keith O. Yeates; Katherine Healey; Gerard A. Gioia; Roger L. Zemek; Abstract OBJECTIVE: To investigate whether preinjury physical, emotional, cognitive, and sleep symptoms on the Post-Concussion Symptoms Inventory (PCSI) are associated with persistent postconcussion symptoms (PPCS) at 4 weeks and whether any associations are moderated by sex or age. STUDY SETTING AND PARTICIPANTS: A total of 3063 participants with acute concussion, presenting to 9 Canadian pediatric emergency departments, were enrolled from August 2013 to June 2015. DESIGN: A planned secondary analysis of a prospective, multicenter cohort study (Predicting Persistent Post-concussive Problems in Pediatrics or 5P). Primary outcome was PPCS at 4 weeks, defined as 3 or more new or worsening individual symptoms compared with the preinjury score at 28 days on the PCSI. The association between preinjury scores and PPCS was analyzed with a multivariable logistic regression analysis that included preinjury, sex, age, sex Èù preinjury, and age Èù preinjury interactions as predictors. Missing baseline covariates were imputed. RESULTS: A total of 2123 (n = 844 [39.8%] girls; median [IQR] age = 12.9 [10.7, 15.0] participants were included in the analysis. Preinjury physical symptom score was associated with PPCS at 4 weeks (Îç2 = 13.87, df = 6, P = .031). The preinjury emotional score also contributed to the variability in PPCS (Îç2 = 11.79, df = 6, P = .067). While girls reported higher preinjury physical, emotional, and cognitive scores than boys, neither sex nor age interacted with preinjury to predict PPCS at 4 weeks. Independent of age and sex, preinjury physical symptoms were associated with PPCS at 4 weeks (OR = 1.40; 95% CI, 1.15-1.70). CONCLUSION: Preinjury physical symptoms are associated with the probability of having PPCS at 4 weeks postconcussion independent of age and sex. Providers should consider preinjury symptoms to inform prognosis and recovery management.