Mild Traumatic Brain Injury Burden in New Zealand: A Population-based Incidence and Short Term Outcomes Study

Abstract

Traumatic brain injury (TBI) is a significant public health concern nationally and internationally. Mild TBI accounts for up to 90% of all TBIs. The majority of those who experience a mild TBI make a full recovery. However, despite the term “mild”, an estimated 15% to 50% experience persistent symptoms which affect their personal, family and social lives (Bazarian & Atabaki, 2001). This study is a prospective population based study of mild TBI, which aimed to establish the true incidence of mild TBI; describe the short term outcome in patients with mild TBI; identify factors associated with persisting problems; and establish the usefulness of further categorising mild TBI for the purposes of predicting outcomes. Participants included all adult residents of Hamilton and Waikato districts in the central North Island of New Zealand (NZ), who sustained a new mild TBI between 1st March 2010 and 28th February 2011. Participants were assessed at baseline, one and six month follow-ups in the areas of neuropsychological functioning, health related quality of life functioning, social and community integration. The overall incidence for non-Māori was 301 per 100 000, with a substantially higher rate of 1,026 cases per 100 000 population for NZ’s indigenous (Māori) people. These are considerably higher rates than those previously reported, highlighting the severity of this seemingly “mild” problem. In addition to this ethnic difference, other at risk groups includes males, those in the younger and the older age groups. In terms of outcomes, deficits in psychological, social, health related quality of life and cognitive functioning were evident within two weeks of injury; as expected, these improved overtime, except attention. Given the high incidence rates reported, and persistent deficits by six months post-injury, mild TBI no doubt warrants attention. These findings have implications for the management of mild TBI.