Background The number of non-hospitalised cases of traumatic brain injury (TBI) exceeds hospitalised cases, and the extent of disability following non-hospitalised TBI is unknown.

Aims/Objectives/Purpose Document the lifetime history of TBI in a general population survey and assess the relationship of lifetime TBI severity to outcomes.

Methods A total of 2701 Coloradoans participated in a random-digit-dialed computer assisted telephone interview. Using an adaptation of the Ohio State University TBI Identification Method, a lifetime history of injury was collected with details about the severity and place of treatment; brief standardised measures assessed current health status, disability, and related outcomes.

Results/Outcomes Respondents were categorised into four injury groups: 24% reported no lifetime injuries, 37% reported injuries but none including TBI, 14% reported one or more TBIs but none with loss of consciousness, and 24% reported one or more TBIs with loss of consciousness. Among those reporting TBI, 24% reported their most severe TBI was treated in a hospital, 38% reported emergency department treatment, 12% were seen in a physician's office or clinic, and 25% stated they did not seek medical attention. After controlling for age, gender, race/ethnicity, and place of treatment, the four injury groups were significant predictors of cognitive impairment, post concussive symptoms, health status, and life satisfaction.

Significance/Contribution to the Field Substantial numbers of the general population (38%) report having one or more TBIs during their lifetime, but only 24% report being hospitalised. Prior estimates of disability after TBI based on hospitalised cases are likely underestimates.