Epidemiology of severe brain injuries: A prospective population-based study

Background: The aim of this prospective study was to estimate annual incide nces of hospitalization for severe traumatic brain injury (TBI) (maximum Ab breviated Injury Score in the head region [HAIS] 4 or 5) in a defined popul ation of 2.8 million. Methods. Severe TBI patients were included in the emergency departments in the 19 hospitals of the region. A prospective data form was completed with initial neurologic state, computed tomographic scan lesions, associated inj uries, length of unconsciousness, and length of stay in acute care centers. Outcome at the time the patient left acute hospitalization was retrospecti vely assessed from medical notes. Results. During the 1-year period (1996), 497 residents fulfilled the inclu sion criteria, leading to an annual incidence rate of 17.3 per 100,000 popu lation; 58.1% were HAIS5. Mortality rate was 5.2 per 100,000. Men accounted for 71.4% of cases. Median age was 44 years, with a quarter of patients mo re than 70 years old. Traffic accidents were the most frequent causes (48.3 %), but falls accounted for 41.8% of all patients. Age and severity were di fferent according to the major categories of external causes. In HAIS5 pati ents, 86.5% were considered as comatose (coma lasting more than 24 hours or leading to immediate death) but only 60.9% had an initial Glasgow Coma Sca le score < 9. In the HAIS4 group, 7.2% had an initial Glasgow Coma Scale sc ore < 9. Fatality rates were 30.0% in the whole study group, 7.7% in HAIS4, 12.8% in HAIS5 without coma, and 51.2% in HAIS5 with coma. Conclusion. This study shows a decrease in severe TBI incidence when result s are compared with another study conducted 10 years earlier in the same re gion. This is because of a decrease in traffic accidents. However, this res ults in an increase in the proportion of falls in elderly patients and an i ncrease in the median age in our patients. This increased age influences th e mortality rate.