The epidemiology of head injuries in Sweden from 1987 to 2000

The purpose of the present study was to evaluate the variability in the annual head injury incidence rate in Sweden from 1987 to 2000. It was hypothesized that the annual incidence rate would decrease over time due to a variety of primary preventive strategies that have been introduced in Swedish society. We used the Hospital Discharge Register at the National Board for Health and Welfare and head injury codes 800-804, and 850-854 from ICD9 system and S2.0-S2.9, and S6.0-S6.9 codes from ICD-10 system. We evaluated the patterns of age, gender, external cause of injury (E-code), type of injury, length of hospital stay, and trends over time. Head injuries due to transportation collision were reduced over the 14-year period analysis. Falls persisted as the dominant cause of head injury. Overall, men had 2.1 times the incidence of head injury compared to women. There was a decline in younger ages experiencing a head injury over this interval, while the number of head injuries among elderly people increased over time. Concussion was about three times more frequent than fractures. Hematoma and diffuse or focal contusions had a much lower incidence rate than concussion. Concussions and fractures decreased over time. Diffuse or focal injuries showed a steady rate of occurrence over the study interval while hematoma increased. Although length of hospital stay varied widely from zero to more than 50 days, 73.6% of hospital days were confined to two days or less. The incidence rate is stable over this time frame. While head injuries attributable to transportation accidents decreased, falls made up an increasing proportion of head injuries. Since we observed an increase in head injuries among elderly, primary prevention strategies may need to be targeted at this age group, and at preventing falls.