title: Self-reported concussion history: impact of providing a definition of concussion.
abstract: BACKGROUND
  In recent years, the understanding of concussion has evolved in the research and medical communities to include more subtle and transient symptoms. The accepted definition of concussion in these communities has reflected this change. However, it is unclear whether this shift is also reflected in the understanding of the athletic community.
  Self-reported concussion history is an inaccurate assessment of someone's lifetime exposure to concussive brain trauma. However, unfortunately, in many cases it is the only available tool.
  
  
  OBJECTIVE
  We hypothesize that athletes' self-reported concussion histories will be significantly greater after reading them the current definition of concussion, relative to the reporting when no definition was provided. An increase from baseline to post-definition response will suggest that athletes are unaware of the currently accepted medical definition.
  
  
  METHODS
  Cross-sectional study of 472 current and former athletes.
  
  
  METHODS
  Investigators conducted structured telephone interviews with current and former athletes between January 2010 and January 2013, asking participants to report how many concussions they had received in their lives. Interviewers then read participants a current definition of concussion, and asked them to re-estimate based on that definition.
  
  
  RESULTS
  THE TWO ESTIMATES WERE SIGNIFICANTLY DIFFERENT (WILCOXON SIGNED RANK TEST: z=15.636, P<0.001). Comparison of the baseline and post-definition medians (7 and 15, respectively) indicated that the post-definition estimate was approximately twice the baseline. Follow-up analyses indicated that this effect was consistent across all levels of competition examined and across type of sport (contact versus non-contact).
  
  
  CONCLUSIONS
  Our results indicate that athletes' current understandings of concussions are not consistent with a currently accepted medical definition. We strongly recommend that clinicians and researchers preface requests for self-reported concussion history with a definition. In addition, it is extremely important that researchers report the definition they used in published manuscripts of their work.
  
  
  CONCLUSIONS
  Our study shows that unprompted reporting of concussion history produces results that are significantly different from those provided after a definition has been given, suggesting one possible mechanism to improve the reliability of self-reported concussion history across multiple individuals.
authors.affiliation: Center for the Study of Traumatic Encephalopathy, Boston University School of Medicine, Boston, MA, USA.
authors.forename: Clifford A
authors.initials: CA
authors.lastname: Robbins
authors.affiliation: Center for the Study of Traumatic Encephalopathy, Boston University School of Medicine, Boston, MA, USA ; Department of Neurology, Boston University School of Medicine, Boston, MA, USA.
authors.forename: Daniel H
authors.initials: DH
authors.lastname: Daneshvar
authors.affiliation: Center for the Study of Traumatic Encephalopathy, Boston University School of Medicine, Boston, MA, USA ; School of Medicine and Biomedical Sciences, University of Buffalo, Buffalo, NY, USA.
authors.forename: John D
authors.initials: JD
authors.lastname: Picano
authors.affiliation: Center for the Study of Traumatic Encephalopathy, Boston University School of Medicine, Boston, MA, USA ; Department of Psychology, University of Colorado, Colorado Springs, CO, USA.
authors.forename: Brandon E
authors.initials: BE
authors.lastname: Gavett
authors.affiliation: Center for the Study of Traumatic Encephalopathy, Boston University School of Medicine, Boston, MA, USA ; Department of Neurology, Boston University School of Medicine, Boston, MA, USA.
authors.forename: Christine M
authors.initials: CM
authors.lastname: Baugh
authors.affiliation: Center for the Study of Traumatic Encephalopathy, Boston University School of Medicine, Boston, MA, USA.
authors.forename: David O
authors.initials: DO
authors.lastname: Riley
authors.affiliation: Center for the Study of Traumatic Encephalopathy, Boston University School of Medicine, Boston, MA, USA ; Department of Neurology, Boston University School of Medicine, Boston, MA, USA ; Sports Legacy Institute, Waltham MA, USA.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Nowinski
authors.affiliation: Center for the Study of Traumatic Encephalopathy, Boston University School of Medicine, Boston, MA, USA ; Department of Neurology, Boston University School of Medicine, Boston, MA, USA ; United States Department of Veterans Affairs, VA Boston Healthcare System, Boston, MA, USA ; Department of Pathology, Boston University School of Medicine, Boston, MA, USA ; Alzheimer's Disease Center, Boston University School of Medicine, Boston, MA, USA.
authors.forename: Ann C
authors.initials: AC
authors.lastname: McKee
authors.affiliation: Center for the Study of Traumatic Encephalopathy, Boston University School of Medicine, Boston, MA, USA ; Sports Legacy Institute, Waltham MA, USA ; Department of Neurosurgery, Boston University School of Medicine, Boston, MA, USA ; Department of Neurosurgery, Emerson Hospital, Concord, MA, USA.
authors.forename: Robert C
authors.initials: RC
authors.lastname: Cantu
authors.affiliation: Center for the Study of Traumatic Encephalopathy, Boston University School of Medicine, Boston, MA, USA ; Department of Neurology, Boston University School of Medicine, Boston, MA, USA ; Alzheimer's Disease Center, Boston University School of Medicine, Boston, MA, USA ; Department of Neurosurgery, Boston University School of Medicine, Boston, MA, USA.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Stern
keywords: concussion; self-report; sports-related concussion