employment in the TBI group 34 years old or older reflects the likelihood that older people are typically in positions of greater responsibility in the Army, including leadership and managerial positions. They theorize that the TBI group may have had a disproportionate amount of difficulty in maintaining employment after injury, which led to an increase in medical discharges.

PRIMARY STUDIES OF CIVILIAN POPULATIONS

Dikmen et al. (1995) examined 466 people with TBI and compared them with 124 trauma controls (people who had sustained bodily injury but not to the head) and with 88 healthy friend controls (people who had not sustained any injury). Subjects were drawn from three prospective longitudinal studies of outcome and were followed from the time of injury until a year after the injury (see Chapter 5). Social functioning was evaluated with the GOS, a rating based on dependence on others for self-care and the ability to participate in normal social life. A structured interview provided information about independent living, school, employment, and income. The SIP, a self-report measure of functioning in 12 activities of living, was also administered. The subjects with TBI were stratified by severity of injury. More severe TBI was related to worse outcome compared to trauma controls on all measures of social functioning except return to school. The absence of a detectable difference in rates of return to school between TBI and trauma controls might reflect the requirement that schools accommodate students with a variety of disabilities. A higher proportion of patients in each of the TBI severity groups, except the most mildly injured, was rated as significantly disabled, according to the GOS, than the trauma controls—for example, percentage with good outcome: trauma controls, 93%; with respect to the TBI group, those with time to follow commands (TFC) 1–6 days, 69%; TFC 7–13 days, 59%; TFC 14–28 days, 31%; TFC over 28 days, 10%; Glasgow Coma Scale (GCS) 9–12, 64%; GCS 6–8, 38%; GCS 3–5, 26% (p < 0.05 by Tukey’s post hoc comparison for each TBI severity group indicated vs trauma controls). Statistically significantly fewer TBI subjects (76%) than trauma controls (93%) returned to living independently at 1 year after injury (p < 0.001). Increasing length of coma was significantly related to decreasing likelihood of returning to independent living at 1 year: those with less than 1 hour of coma, 89%; 1–24 hours, 89%; 1–6 days, 74%; 7–13 days, 49%; 14–28 days, 55%; and 29 days or longer, 23% (r = 0.49; p < 0.001). Fewer TBI subjects (49%) than trauma controls (63%) were working 1 year after injury (p < 0.05). The more severe the TBI, the less likely the person returned to work: of those with less than 1 hour of coma, 64% had returned to work; 1–24 hours, 50%; 1–6 days, 51%; 7–13 days, 36%; 14–28 days, 18%; and 29 days or longer, 6%. In a subgroup of the same sample, McLean et al. (1993) also found a lower rate of return to work in participants with TBI than in friend controls (p < 0.01). The TBI subjects earned less than trauma controls in the year after injury, and within the TBI group increasing length of coma was associated with decreasing income (Dikmen et al., 1995).


TBI subjects reported more dysfunction than trauma controls on the SIP, especially on scales assessing psychosocial, rather than physical, limitations. For example, the TBI subjects (mean, 23) reported significantly more dysfunction than the trauma controls (mean, 14) on the Work Scale (p < 0.001) and on the Psychosocial Summary Scale (mean dysfunction, 11 vs 8, respectively; p < 0.01), indicating difficulties in communication, alertness behavior, emotional behavior, and social interaction. There were no significant differences between TBI patients and trauma controls on the Physical Summary Scale, which evaluates ambulation, mobility, body



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