The epidemiology of moderate and severe traumatic brain injury in Central Norway

Introduction: Few studies account for prehospital deaths when estimating incidence and mortality rates of moderate and severe traumatic brain injury (msTBI). In a population-based study, covering both urban and rural areas, including also prehospital deaths, the aim was to estimate incidence and mortality rates of msTBI. Further, we studied the 30-day and 6-month case-fatality proportion of severe TBI in relation to age. Methods: All patients aged >= 17 years who sustained a msTBI in Central Norway were identified by three sources: 1) the regional trauma center, 2) the general hospitals, and 3) the Norwegian Cause of Death Registry. Incidence and mortality rates were standardized according to the World Health Organization's world standard population. Case-fatality proportions were calculated by the number of deaths from severe TBI at 30 days and 6 months, divided by all patients with severe TBI. Results: The overall incidence rates of moderate and severe TBI were 4.9 and 6.7 per 100,000 person-years, respectively, increasing from age 70 years. The overall mortality rate was 3.4 per 100,000 person-years, also increasing from age 70 years. Incidence and mortality rates were highest in men. The case-fatality proportion in people with severe TBI was 49% in people aged 60-69 years and 81% in people aged 70-79 years. Discussion/Conclusion: The overall incidence and mortality rate for msTBI in Central Norway was low but increased from age 70, and among those >= 80 years of age with severe TBI, nearly all died. Overall estimates are strongly influenced by high incidence and mortality rates in the elderly, and studies should therefore report age-specific estimates, for better comparison of incidence and mortality rates.