Counting heads: estimating traumatic brain injury in New South Wales

The public health problem of head injuries contributes to considerable morbidity in the community and is the commonest cause of death in young adult Australians. However, estimating the incidence of head injury has been difficult, and has varied between countries and over time. This paper critically appraises the methodological issues contributing to head injury/brain injury incidence estimates, in particular case definition, differing data sources, and methods of case ascertainment. The most appropriate definition from a methodological service provider perspective is one which clearly distinguishes between potential and actual brain injury. The results from a study which used the most accurate methods have been extrapolated to NSW, and reduce the estimated brain injury incidence in NSW from a reported 392 to 180 per 100,000 incident cases per year. This revised estimate implies that in 1990 there will be about 10,500 new cases of traumatic brain injury, of which an estimated 400 will result in serious physical or mental disability. These estimates were originally calculated to enable the development of an appropriate level of health service provision for brain-injured persons through the NSW Brain Injury Program.