title: Systematic review of prognosis and return to play after sport concussion: results of the International Collaboration on Mild Traumatic Brain Injury Prognosis.
abstract: OBJECTIVE
  To synthesize the best available evidence on prognosis after sport concussion.
  
  
  METHODS
  MEDLINE and other databases were searched (2001-2012) with terms including "craniocerebral trauma" and "sports." Reference lists of eligible articles were also searched.
  
  
  METHODS
  Randomized controlled trials and cohort and case-control studies were selected according to predefined criteria. Studies had to have a minimum of 30 concussion cases.
  
  
  METHODS
  Eligible studies were critically appraised using a modification of the Scottish Intercollegiate Guidelines Network (SIGN) criteria. Two reviewers independently reviewed and extracted data from accepted studies into evidence tables.
  
  
  RESULTS
  Evidence was synthesized qualitatively according to modified SIGN criteria, and studies were categorized as exploratory or confirmatory based on the strength of their design and evidence. After 77,914 records were screened, 52 articles were eligible for this review, and 24 articles (representing 19 studies) with a low risk of bias were accepted. Our findings are based on exploratory studies of predominantly male football players at the high school, collegiate, and professional levels. Most athletes recover within days to a few weeks, and American and Australian professional football players return to play quickly after mild traumatic brain injury. Delayed recovery appears more likely in high school athletes, in those with a history of previous concussion, and in those with a higher number and duration of postconcussion symptoms.
  
  
  CONCLUSIONS
  The evidence concerning sports concussion course and prognosis is very preliminary, and there is no evidence on the effect of return-to-play guidelines on prognosis. Our findings have implications for further research. Well-designed, confirmatory studies are urgently needed to understand the consequences of sport concussion, including recurrent concussion, across different athletic populations and sports.
authors.affiliation: Division of Health Care and Outcomes Research, Toronto Western Research Institute, University Health Network, University of Toronto, Toronto, Ontario, Canada; Institute of Health Policy, Management and Evaluation, University of Toronto, Toronto, Ontario, Canada. Electronic address: ccancell@uhnresearch.ca.
authors.forename: Carol
authors.initials: C
authors.lastname: Cancelliere
authors.affiliation: Division of Health Care and Outcomes Research, Toronto Western Research Institute, University Health Network, University of Toronto, Toronto, Ontario, Canada; Division of Epidemiology, Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Cesar A
authors.initials: CA
authors.lastname: Hincapié
authors.affiliation: Departments of Occupational Science and Occupational Therapy, Psychology and Graduate Department of Rehabilitation Science, University of Toronto, Toronto, Ontario, Canada; Bloorview Research Institute, Holland Bloorview Kids Rehabilitation Hospital, Toronto, Ontario, Canada.
authors.forename: Michelle
authors.initials: M
authors.lastname: Keightley
authors.affiliation: Department of Clinical Sciences, Rehabilitation Medicine, Karolinska Institutet, Danderyd University Hospital, Stockholm, Sweden.
authors.forename: Alison K
authors.initials: AK
authors.lastname: Godbolt
authors.affiliation: Institute of Health Policy, Management and Evaluation, University of Toronto, Toronto, Ontario, Canada; Division of Epidemiology, Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada; Faculty of Health Sciences, University of Ontario Institute of Technology, Oshawa, Ontario, Canada; UOIT-CMCC Centre for the Study of Disability Prevention and Rehabilitation, Toronto, Ontario, Canada.
authors.forename: Pierre
authors.initials: P
authors.lastname: Côté
authors.affiliation: Division of Epidemiology, Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada; Department of Health Sciences, Lakehead University, Thunder Bay, Ontario, Canada; Institute for Work and Health, Toronto, Ontario, Canada.
authors.forename: Vicki L
authors.initials: VL
authors.lastname: Kristman
authors.affiliation: Department of Community Medicine and Rehabilitation, Rehabilitation Medicine, Umeå University, Umeå, Sweden.
authors.forename: Britt-Marie
authors.initials: BM
authors.lastname: Stålnacke
authors.affiliation: School of Public Health and Alberta Centre for Injury Control and Research, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: Linda J
authors.initials: LJ
authors.lastname: Carroll
authors.affiliation: Department of Rehabilitation and Complex Continuing Care, Holland Bloorview Kids Rehabilitation Hospital, Toronto, Ontario, Canada; Department of Pediatrics, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Ryan
authors.initials: R
authors.lastname: Hung
authors.affiliation: Department of Clinical Sciences, Rehabilitation Medicine, Karolinska Institutet, Danderyd University Hospital, Stockholm, Sweden.
authors.forename: Jörgen
authors.initials: J
authors.lastname: Borg
authors.affiliation: Department of Clinical Sciences, Rehabilitation Medicine, Karolinska Institutet, Danderyd University Hospital, Stockholm, Sweden.
authors.forename: Catharina
authors.initials: C
authors.lastname: Nygren-de Boussard
authors.affiliation: National Center for Injury Prevention and Control, Centers for Disease Control and Prevention, Atlanta, GA.
authors.forename: Victor G
authors.initials: VG
authors.lastname: Coronado
authors.affiliation: Division of Health Care and Outcomes Research, Toronto Western Research Institute, University Health Network, University of Toronto, Toronto, Ontario, Canada.
authors.forename: James
authors.initials: J
authors.lastname: Donovan
authors.affiliation: Division of Health Care and Outcomes Research, Toronto Western Research Institute, University Health Network, University of Toronto, Toronto, Ontario, Canada; Institute of Health Policy, Management and Evaluation, University of Toronto, Toronto, Ontario, Canada; Division of Epidemiology, Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada; Institute of Sports Science and Clinical Biomechanics, Faculty of Health, University of Southern Denmark, Odense, Denmark.
authors.forename: J David
authors.initials: JD
authors.lastname: Cassidy
mesh_terms: D056352:Athletes; D001924:Brain Concussion / Q000150:complications / Q000175:diagnosis*; D003072:Cognition Disorders / Q000209:etiology; D006801:Humans; D009483:Neuropsychological Tests; D038223:Post-Concussion Syndrome / Q000175:diagnosis / Q000209:etiology; D011379:Prognosis; D020127:Recovery of Function; D012008:Recurrence; D013177:Sports; D015599:Trauma Severity Indices
keywords: Athletic injuries; Brain concussion; Prognosis; Rehabilitation; Sports