14 “if in doubt, sit them out” 3. OVERVIEW OF LITERATURE Definition Concussion is a type of brain injury. It is recognised as a complex injury that is challenging to evaluate and manage. The Concussion in Sport Group (CISG) has hosted five International Consensus Conferences since 2001. After each conference the CISG has published a statement summarising available evidence. Consensus statement recommendations from the Berlin conference in 2016 provide guidance to clinicians and others managing sport-related concussion3 . As defined by the international Consensus Statement, sport-related concussion is ‘a traumatic brain injury induced by biomechanical forces’3,4 .It generally results from a knock – often to the head, face or neck but may be anywhere in the body – which transmits an impulsive force to the head. Concussion commonly involves short-lived impairment of neurological function. Concussion is an evolving injury that may change over the first few hours and sometimes over a few days. In adults in most cases symptoms have resolved by 14 days post injury3 . It is yet unclear whether concussion involves mild structural changes, which would position it within the traumatic brain injury spectrum, or only physiological changes3 . As discussed below, some epidemiological data, particularly hospital data, do not distinguish between traumatic brain injury and concussion. Epidemiology Sport-related concussion is a public health concern in Australia. Precise data on the incidence of sport-related concussion in Australia is lacking. Potential limitations to obtaining accurate data on incidence include lack of recognition of symptoms, under-reporting by athletes and failing to seek medical advice. A study examining the annual rate of hospitalisations for sport-related concussions in Victoria demonstrated a significant increase in frequency from 443 per year in 2002-03 to 621 in 2010-11, an increase of 60.5 per cent over the nine-year period1 . This was not explained by increased participation, since rates of concussion per 100,000 participants also increased significantly during this time (38.5 per cent). Hospitalisation rates for concussion across different sports have been examined, and when adjustments were made for participation rates, the sports with the highest concussion rates were determined to be motor sports (181.8/100,000), equestrian (130.3/100,000), Australian football (80.3/100,000), all codes of rugby (49.9/100,000), and roller sports (44.8/100,000)1 . Sport-related concussion rates in the United States are estimated to be up to 3.8 million per year33 . The condition is thought to be under-reported, making the actual incidence of concussion in the community difficult to quantify34 . This problem is further complicated by the lack of an objective laboratory or diagnostic test for concussion and the reliance on more subjective methods of diagnosis14 . Aside from health concerns, concussions and traumatic brain injuries represent a significant economic cost to the community. There are few figures available for hospital costs specific to concussion. The costs for hospital admissions involving traumatic brain injury in Australia however were $184 million in the year 2004-0535 . The majority of traumatic brain injuries occur in the 15-64 year age group, representing the group most likely to be in the workforce35 . Victorian data for nine years (2002-2011) estimated the costs of hospital admissions for sport-related concussions as $1,993,867 per annum1 . These figures represent only a portion of the economic costs involved, as they do not reflect costs to the individual and income and productivity losses.