regard to CHART components, 16% were impaired or disabled; and 29% reported less than good quality of life. The authors concluded that “substantial percentages of people hospitalized with TBI in a population-based sample reported a variety of problematic outcomes at 1 year postinjury.” It is noteworthy that the problems experienced by members of that injury cohort were in many cases similar in all levels of initial TBI severity.
The second study of the incidence of disability was a South Carolina population-based prospective cohort study reported by Pickelsimer et al. (2006). Followup was completed at 1 year after injury with such outcome measures as service needs, psychosocial health, health-related quality of life, functional status, TBI-related symptoms, employment, and life satisfaction. Outcome findings included one or more functional limitations in about 47% of the subjects, unmet service needs in about one-third (35%), and dissatisfaction in quality of life in about one-third (35%). In a second report of that study, Selassie et al. (2008) used the same population sample and outcome measures to estimate the incidence of long-term disability in the United States. The researchers concluded that among the 288,009 survivors hospitalized for TBI in 2003, almost 125,000 (over 43%) had long-term disability. The disability rate varied by age and sex; it was higher in females than in males and was highest in people who fell and in those with self-inflicted injuries.
Information on annual disability does not quantify the cumulative prevalence of TBI disability or impairment in the population. If 43% of a hospital-discharged TBI population sustains some form of disability or impairment in 1 year, the question remains, how much of the total population is disabled or impaired from TBI sustained in earlier years? Thurman and colleagues (1999) attempted to estimate that number by using the US National Hospital Discharge Survey data to approximate incidence and then classified the data by TBI severity by applying the computer algorithm known as ICDMAP-90 developed by MacKenzie et al. (1989b). The probability of disability was estimated for each level of severity by using outcome findings on disability from the Colorado state TBI registry and estimation parameters developed by Kraus and McArthur (1996). On the basis of that model, CDC estimated that 5.3 million US citizens (2%) were living with TBI-related disability in 1996. If that proportion is applied to the 2007 US population of over 301 million people, then just over 6 million people are living with the effects of TBI, and 2 million people have unmet health-service needs.
As discussed above, LOC is the most common measure used for evaluating brain injury severity and the most widely used tool for LOC is the GCS. Problems that arise in comparing the GCS measured in different places come from differences in timing. For example, intubation and sedation of the brain-injured patient during transport to the ED will obviously affect the person's verbal and motor abilities and eye responses. Differences in timing in the administration of any measurement tool can be critical so Teasdale and Jennett suggested that the GCS be applied at 6 hours post-injury. However, because a patient's injury may require ED procedures like intubation and sedation or acute surgical intervention, repeat measures may be necessary, often minutes or hours apart. Hence there does not appear to be an ideal window that is the best for the GCS, but, if it is to have any predictive quality, it should be applied early in the clinical management of TBI.