Head injury with and without hospital admission: comparisons of incidence and short-term disability.

All persons with head injuries (skull fracture or injury to the cranial contents resulting in a physician visit or at least one day of disability), regardless of treatment or hospital admission status, were identified from National Health Interview Survey data for the years 1977-81. Among those who reported such head injuries within the two weeks prior to interview, only 16 per cent were admitted to hospitals. Children, members of low-income families, and those injured at home, school, or in a recreational setting were less likely to be admitted to hospital than others. Among those who sustained a head injury in the previous three months and had some disability from that injury during the two weeks prior to interview, those not admitted to hospital included one-half of those with three to seven days of bed disability and one-third of those with more than seven days of bed disability; and they accounted for one-half of all disability days. These findings indicate that hospital-based head injury incidence data are incomplete and may contain substantial biases.