title: Risk modifiers for concussion and prolonged recovery.
abstract: BACKGROUND
  Currently, no consensus exists for grading the severity of concussions. Identification of risk factors that may affect concussion risk and the likelihood of prolonged recovery can be of value to providers who manage concussion.
  
  
  METHODS
  Relevant studies were identified through MEDLINE (1996-2011) using the keywords concussion, postconcussive syndrome, and risk or risk factor. Targeted searches for specific risk factors were conducted with additional keywords, such as gender and migraine. Manual review of reference lists was also performed to identify pertinent literature.
  
  
  RESULTS
  For risk factors of concussion, history of prior concussion and female sex have the most supporting evidence. Sports with consistently high risk for sustaining a concussion include football, men's ice hockey, and women's soccer. Younger athletes appear to be more susceptible to concussion, but data are limited and inconsistent. Protective equipment does not definitively alter concussion risk, though it protects against other injuries. Symptoms such as long headaches, migraines, amnesia, and multiple symptoms appear to be associated with prolonged recovery. Younger age may also increase the risk of prolonged concussion.
  
  
  CONCLUSIONS
  High-quality evidence for risk modifiers in concussion remains sparse. Prior concussion, collision sports, female sex, and women's soccer are the strongest known risk factors. Evidence for most other factors is inconclusive.
authors.affiliation: Maine Medical Center Sports Medicine, Portland, Maine.
authors.forename: Kristen A
authors.initials: KA
authors.lastname: Scopaz
authors.affiliation: Maine Medical Center Sports Medicine, Portland, Maine.
authors.forename: John R
authors.initials: JR
authors.lastname: Hatzenbuehler
keywords: concussion; postconcussive syndrome; risk factors; risk modifiers