Dikmen et al. (1995c) examined 466 people who were enrolled as part of the Behavioral Outcome of Head Injury Study (21% of the subjects), the Patient Characteristics and Head Injury Outcome Study (50%), or the Dilantin Prophylaxis of Post-Traumatic Seizures Study (29%). The controls were 124 trauma controls from the Patient Characteristics and Head Injury Outcome Study who had sustained bodily injury but not to the head and 88 healthy friends from the Behavioral Outcome of Head Injury Study. Analyses weighted the cases to adjust the mix of severity and pre-existing conditions to approximate that of the unselected Patient Characteristics and Head Injury Outcome Study. Social function was evaluated with the Glasgow Outcome Scale; a structured interview was conducted to collect information on independent living, school, employment, and income. The Sickness Impact Profile (SIP) was also administered. The head-injured were stratified by severity of injury. More severe TBI was related to worse outcome on all measures of social functioning except return to school, in which no difference was detected between TBI patients and trauma controls.
Return to work and other neurocognitive outcomes after head injury were assessed in subgroups of the same population (Fraser et al., 1988; McLean et al., 1993; Dikmen et al., 1994; Doctor et al., 2005). Fraser et al. (1988) found poorer neuropsychologic test scores and more dysfunction on the SIP physical scales at 1 month after injury in those who failed to return to work by 1 year after injury compared with those who had returned to work. McLean et al. (1993) assessed employment issues related to head trauma and found that in addition to a lower rate of return to work, participants with TBI were less likely to have remained at the same or similar position (36%) than the friend controls (60%). Dikmen et al. (1994) assessed time to return to work in 366 head-injured patients and 95 trauma controls who worked preinjury. The study participants were drawn from the three studies mentioned previously (45% from the Patient Characteristics and Head Injury Outcome Study, 33% from the Dilantin Prophylaxis of Post-Traumatic Seizures Study, and 22% from the Behavioral Outcome of Head Injury Study). Preinjury workers were followed for 1–2 years after injury to measure the time from injury to first return to work regardless of the length of the employment. Time to return to work was related to severity of TBI. Doctor et al. (2005) used a longitudinal inception cohort design and the same population as Dikmen et al. (1994) and additional TBI subjects from the Valproate Prophylaxis of Post-Traumatic Seizures Study. Employment was assessed at 1 year after injury in 418 TBI subjects who were working before their injuries and compared with expected unemployment rates from a current population survey. The authors found a substantial increase in risk of unemployment after TBI that increased with severity.
Several secondary studies have addressed other social outcomes. Patients with moderate to severe TBI were examined over a 2-year period. In spite of improvement, many subjects were unable to return to work, to support themselves financially, to live independently, or to participate in leisure activities for at least 2 years after injury (Dikmen et al., 1993). The authors examined alcohol use before and after injury and in relation to ED blood alcohol concentrations (Dikmen et al., 1995a); 42% of the subjects were intoxicated on arrival at the ED. The amount of drinking and associated problems decreased immediately after injury but were followed by an increase by 1 year although not to the same levels. Patients with more severe injuries decreased their drinking more than those with mild TBI. Blood alcohol in the ED was a good indicator of a history of problem drinking.
Burden to spouse and significant others was examined in the same cohort at 6 months after injury (Machamer et al., 2002). Significant others reported both favorable and unfavorable