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When should an athlete retire or discontinue participating in contact or collision sports following sport-related concussion? A systematic review
  1. Michael Makdissi1,2,
  2. Meghan L Critchley3,
  3. Robert C Cantu4,
  4. Jeffrey G Caron5,6,
  5. Gavin A Davis7,8,
  6. Ruben J Echemendia9,10,
  7. Pierre Fremont11,
  8. K Alix Hayden12,
  9. Stanley A Herring13,
  10. Sidney R Hinds14,
  11. Barry Jordan15,
  12. Simon Kemp16,17,
  13. Michael McNamee18,19,
  14. David Maddocks20,
  15. Shinji Nagahiro21,
  16. Jon Patricios22,
  17. Margot Putukian23,
  18. Michael Turner24,25,
  19. Stacy Sick3,
  20. Kathryn J Schneider3,26,27
  1. 1 Australian Football League, Melbourne, Victoria, Australia
  2. 2 Melbourne Brain Centre, Florey Institute of Neuroscience and Mental Health - Austin Campus, Heidelberg, Victoria, Australia
  3. 3 Sport Injury Prevention Research Centre, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
  4. 4 Neurosurgery, Boston University School of Medicine, Boston, Massachusetts, USA
  5. 5 School of Kinesiology and Physical Activity Sciences, Faculty of Medicine, Université de Montréal, Montreal, Québec, Canada
  6. 6 Centre for Interdisciplinary Research in Rehabilitation of Greater Montreal, Montreal, Québec, Canada
  7. 7 Murdoch Children's Research Institute, Parkville, Victoria, Australia
  8. 8 Cabrini Health, Malvern, Victoria, Australia
  9. 9 Psychology, University of Missouri-Kansas City, Kansas City, MO, USA
  10. 10 Orthopedics Center Concussion Care Clinic, State College, Pennsylvania, Pennsylvania, USA
  11. 11 Rehabilitation, Laval University, Quebec, Quebec, Canada
  12. 12 Libraries and Cultural Resources, University of Calgary, Calgary, Alberta, Canada
  13. 13 Departments of Rehabilitation Medicine, Orthopaedics and Sports Medicine and Neurological Surgery, University of Washington, Seattle, Washington, USA
  14. 14 Uniformed Services University, Bethesda, Maryland, USA
  15. 15 Keck School of Medicine, University of Southern California, Los Angeles, California, USA
  16. 16 Sports Medicine, Rugby Football Union, London, UK
  17. 17 London School of Hygiene & Tropical Medicine, London, UK
  18. 18 Department of Movement Sciences, KU Leuven, Leuven, Belgium
  19. 19 School of Sport and Exercise Sciences, Swansea University, Swansea, UK
  20. 20 Perry Maddocks Trollope Lawyers, Melbourne, Victoria, Australia
  21. 21 Department of Neurosurgery, Yoshinogawa Hospital, Tokushima, Japan
  22. 22 Sport and Health (WiSH), School of Clinical Medicine, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
  23. 23 Major League Soccer, Princeton University, Princeton, New Jersey, USA
  24. 24 International Concussion and Head Injury Research Foundation, London, UK
  25. 25 University College London, London, UK
  26. 26 Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
  27. 27 Alberta Children’s Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
  1. Correspondence to Dr Michael Makdissi, Australian Football League, Melbourne, Victoria 3008, Australia; michael.makdissi{at}


Objective To systematically review the scientific literature regarding factors to consider when providing advice or guidance to athletes about retirement from contact or collision sport following sport-related concussion (SRC), and to define contraindications to children/adolescent athletes entering or continuing with contact or collision sports after SRC.

Data sources Medline, Embase, SPORTSDiscus, APA PsycINFO, CINAHL and Cochrane Central Register of Controlled Trials were searched systematically.

Study eligibility criteria Studies were included if they were (1) original research, (2) reported on SRC as the primary source of injury, (3) evaluated the history, clinical assessment and/or investigation of findings that may preclude participation in sport and (4) evaluated mood disturbance and/or neurocognitive deficits, evidence of structural brain injury or risk factors for increased risk of subsequent SRC or prolonged recovery.

Results Of 4355 articles identified, 93 met the inclusion criteria. None of the included articles directly examined retirement and/or discontinuation from contact or collision sport. Included studies examined factors associated with increased risk of recurrent SRC or prolonged recovery following SRC. In general, these were low-quality cohort studies with heterogeneous results and moderate risk of bias. Higher number and/or severity of symptoms at presentation, sleep disturbance and symptom reproduction with Vestibular Ocular Motor Screen testing were associated with prolonged recovery and history of previous concussion was associated with a risk of further SRC.

Conclusion No evidence was identified to support the inclusion of any patient-specific, injury-specific or other factors (eg, imaging findings) as absolute indications for retirement or discontinued participation in contact or collision sport following SRC.

PROSPERO registration number CRD42022155121.

  • Brain Concussion
  • Sport

Data availability statement

All data relevant to the study are included in the article or uploaded as online supplemental information.

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Data availability statement

All data relevant to the study are included in the article or uploaded as online supplemental information.

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  • Twitter @pfremo, @drsimonkemp, @jonpatricios, @Mputukian, @Kat_Schneider7

  • Contributors All authors participated in the development and review of the search terms and strategy for retirement, database selection, inclusion/exclusion criteria, data extraction table and PROSPERO protocol development. AH developed the search strategies and ran the searches in all databases. MC, KJS and MM acted as methods authors. All authors participated in screening, data extraction and risk of bias assessment. MC, KJS and MM designed and completed the results section. All authors participated in the writing, critical review and final approval of the manuscript. MM is the guarantor of the study.

  • Funding This systematic review was prepared for presentation at the 6th International Conference on Concussion in Sport in Amsterdam, October 2022. An education grant was received from the Concussion in Sport International Consensus Conference Organising Committee through Publi Creations for partial administrative and operational costs associated with the writing of the systematic reviews.

  • Competing interests MMakdissi is sport and exercise medicine physician working in private consulting practice. He is a shareholder of Olympic Park Sports Medicine Centre in Melbourne and consultant to the Australian Football League (AFL, chief medical officer) and an Independent Concussion Consultant for World Rugby. He is a former team physician at the Hawthorn Football Club (AFL) and former chief executive officer of the AFL Doctors Association. He has received research grants from the AFL, outside the submitted work and is a chief instigator (unpaid) on projects receiving grants from the Australian Government Department of Health Medical Research and Future Fund. He is on the editorial board of the BJSM (unpaid) and JSAMS (unpaid). He has received travel support from the AFL, FIFA and the International Olympic Committee to attend and present at international conferences. He is a member of the Scientific Committee for the 6th International Consensus Conference on Concussion in Sport (unpaid), International Concussion in Sport Group (unpaid), Australian Rugby Union Concussion Advisory Group (unpaid). RC serves as a scientific advisor for the National Football League’s (NFL) Head Neck and Spine Committee, VP and Chair of the Scientific Advisory Committee for the National Operating Committee on Standards for Athletic Equipment (NOCSAE), and as cofounder and medical director of the Concussion Legacy Foundation. He currently receives research support from the NINDS UNITE and Diagnose CTE grants. He has received travel support and honorariums for presentations at conferences and meetings. He receives royalties from Houghton Mifflin Hardcourt publishing. He has a clinical and consulting practice in forensic neurology and neurosurgery, including expert testimony, especially individuals with traumatic brain and spinal cord injuries. He is a member of the National Collegiate Athletic Association Student-Athlete Concussion Injury Litigation Medical Science Committee. RJE is a paid consultant for the NHL and co-chair of the NHL/NHLPA Concussion Subcommittee. He is also a paid consultant and chair of the Major League Soccer concussion committee, and a consultant to the US Soccer Federation. He previously served as a neuropsychology consultant to Princeton University Athletic Medicine and EyeGuide. He is currently a co-PI for a grant funded by the NFL (NFL-Long) through Boston Children’s Hospital. He occasionally provides expert testimony in matters related to mTBI and sports concussion, and occasionally receives honoraria and travel support/reimbursement for professional meetings. JC has nothing to disclose. GAD is a member of the Scientific Committee of the 6th International Consensus Conference on Concussion in Sport; an honorary member of the AFL Concussion Scientific Committee; Section Editor, Sport and Rehabilitation, NEUROSURGERY; and has attended meetings organised by sporting organisations including the NFL, NRL, IIHF, IOC and FIFA; however, has not received any payment, research funding or other monies from these groups other than for travel costs. PF is a coinvestigator on a research grant from the NFL’s ’Play Smart. Play Safe’ Initiative and an Executive Review committee member of the Canadian Concussion Network (financed by CIHR). He received honorarium for an expert group discussion on blood biomarkers for concussion in December 2020. AH has nothing to disclose. SHerring cofounder and senior advisor, The Sports Institute at UW Medicine (unpaid), Centers for Disease Control and Prevention and National Center for Injury Prevention and Control Board Pediatric Mild Traumatic Brain Injury Guideline Workgroup (unpaid), NCAA Concussion Safety Advisory Group (unpaid), Team Physician, Seattle Mariners, Former Team Physician, Seattle Seahawks, Concussion in Sport Group (travel support), occasional payment for expert testimony, travel support for professional meetings. SHinds provides client consultation services for military/veteran health, neuroscience, health, sports medicine, neurodegenerative disease, neurotrauma, nuclear medicine, molecular imaging, nuclear and radiation accidents and incidents, and health equity. Consult services includes support to Prevent Biometrics; advisor to Synaptek; advisor/consultant for the Collaborative Neuropathology Network Characterizing Outcomes of TBI (CONNECT-TBI); advisor to NanoDX; and reviewer for Peer Reviewed Alzheimer’s Disease Research Program. SHinds is chief of Health Equity and Deputy Medical Director for the NFL Players Association, Medical Director for the MLS Players Association. He receives grant support (no income) from the following: Co-PI, Long-term Impact of Military-relevant Brain Injury Consortium-Chronic Effects of Neurotrauma Consortium (LIMBIC-CENC); Advisory Board member to Concussion Legacy Foundation Project Enlist; Advisory Board member to the University of Michigan Concussion Center; advisor to Gryphon Bio; ad hoc reviewer for VA Brain Health Research; invited reviewer to Congressionally Directed Medical Research Programs; National Academy of Science, Engineering, and Medicine ’Accelerating Progress in TBI Research and Care’; NASEM TBI Forum committee member (currently inactive); contributor to Post-traumatic Epilepsy Former Department of Defense work: NFL Scientific Advisory Board member; NCAA-DoD CARE Medical Advisory Board Member; DoD Brain Health Research Coordinating Officer and Medical Advisor to the Principal Assistant for Research and Technology (PAR&T), US Army Medical Research and Development Command (USAMRDC); Ex Officio National Advisory Neurological Disorders and Stroke (NANDSC) Council Member. BJ has nothing to disclose. SK Medical Services Director, Rugby Football Union (paid), Member of the World Rugby Concussion Expert Group, Member of the FIFA Concussion Expert Group (paid), Member of the FA Independent Concussion Expert Group. MMakdissi reports research grants from the US NIH, US Department of Defense, US CDC, US Department of Veterans Affairs, Abbott Laboratories, NFL and NCAA, and consultancy with the Green Bay Packers and Neurotrauma Sciences. MMcNamee 1. Chair, Ethics Expert Group, WADA (2021–2023) (paid) 2. Member, International Boxing Association, Ethics and Integrity Committee, (2021–2022; resigned October 2022) (paid) 3. Chair, Therapeutic Use Exemption Fairness Committee (2020–) (paid) 4. Member, Steering Group, Sex Segregation in Sport, IAAF/World Athletics, (2019–2020) (unpaid) 5. Member, International Ice Hockey Federation, Ethics and Integrity Committee (2019–2021) (paid) 6. Member, International Olympic Committee Consensus Statement Expert Group on Injuries in Children and Adolescents (2017) (unpaid) 7. Member, Ethics Expert Group, WADA (2016–2021) (unpaid) 8. Member, International Olympic Committee Consensus Statement Expert Group on Pain Management (2016)) (unpaid). SN has nothing to disclose. JP Editor BJSM (honorarium); Member of World Rugby Concussion Advisory Group (unpaid); Independent Concussion Consultant for World Rugby (fee per consultation); Medical consultant to South African Rugby (unpaid); Co-chair of the Scientific Committee, 6th International Conference on Concussion in Sport (unpaid); Board member of the CISG (unpaid); Scientific Board member, EyeGuideTM (unpaid). MP declares the following: Consultant, CMO, Major League Soccer; Senior Advisor, NFL Head, Neck NCAA-CARE- DoD 2.0, ended 2020; Have received honoraria and reimbursement for travel for speaking and conferences attended; Have written chapters for UpToDate, and received royalties for the Netter’s Sports Medicine textbook; Have provided work as an expert for cases involving concussion, team physician and other sports medicine topics. SS has nothing to disclose. MT is employed full-time as the CEO and Medical Director of ICHIRF—a paid post he has held since April 2015. Hon Medical Adviser to the Professional Riders Insurance Scheme (PRIS)—discretionary honorarium. Member of the Premier League Head Injury Advisory Group (HIAG)—no remuneration. Director of ICHIRF Ireland—no remuneration. Honorary Medical Adviser to the Concussion Foundation—no remuneration. Member of the expert panel for the Dept of Digital, Culture, Media and Sport review into concussion in amateur sport—no remuneration. Attendance at conferences or meetings as a guest speaker—reimbursement of travel expenses, complimentary registration and payment of hotel accommodation and meals by the organising committee. No stocks or options in any concussion-related company. No consultancies, board or editorial positions related to concussion. KJS has received grant funding from the CIHR, NFL Scientific Advisory Board, International Olympic Committee Medical and Scientific Research Fund, World Rugby, Mitacs Accelerate, University of Calgary, with funds paid to her institution and not to her personally. She is an Associate Editor of BJSM (unpaid), Independent consultant to World Rugby and has received travel and accommodation support for meetings where she has presented. She coordinated the writing of the systematic reviews that informed Amsterdam International Consensus on Concussion in Sport, for which she has received an educational grant to assist with the administrative costs associated with the writing of the reviews (with funds paid to her institution). She is a member of the AFL Concussion Scientific Committee (unpaid position), Brain Canada (unpaid positions) and Board member of the Concussion in Sport Group (CISG) (unpaid). She works as a physiotherapy consultant and treats athletes of all levels of sport from grass roots to professional.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.

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