A total of 5043 (weighted N=14 477) patients were eligible for the study. Of these, 1245 patients (weighted n=1381) either died in the hospital or died in the days and weeks after hospitalization. A total of 3798 patients (weighted n=13 096) were included in the 3-month assessment; 90 died after the 3-month interview (weighted n=204), and 661 were lost to follow-up (weighted n=2520). A total of 3047 patients (weighted n=10 372), or 82.2% of 3708 eligible injury survivors, completed the 12-month follow-up interview. Patients lost to follow-up were significantly more likely to be younger (mean age, 38.4 years for those lost to follow-up vs 43.0 years for those who completed the interview; t1
<.001) and intentionally injured (32.2% vs 16.4%;
=.001). Relative to white patients, African American (26.2% vs 15.3%;
=.001) and Latino (28.7% vs 15.3%;
=.02) patients were more likely to be lost to follow-up. There were no significant differences in rates of loss to 12-month follow-up for patients in the severe (17.2%), moderate (13.3%), mild (17.5%), and no (22.0%) TBI subgroups (
At the time of injury hospitalization, 20.5% of patients (2123 of 10 372) had experienced severe TBI, 11.7% (1216) moderate TBI, 12.9% (1342) mild TBI, and 54.9% (5691) no TBI. Patients with severe and moderate TBI were more likely to also incur severe facial injuries (). In contrast, patients with mild and no TBI were more likely to incur extremity, thoracic, and abdominal injuries (). Patients in the no-TBI group had significantly lower injury severity (mean [SD] ISS, 13.5[14.4]) relative to patients with severe (26.6 [19.2]), moderate (17.2 [14.4]), and mild (17.9 [15.9]) TBIs (F3,68=188.2, P<.001).
Associations Between Traumatic Brain Injury Subtype and Location of Severe Bodily Injuriesa
At the 12-month postinjury time point, 21.8% of patients (2228 of 10 203) endorsed symptoms consistent with a diagnosis of PTSD on the PCL. In univariate analyses, increasing severity of TBI was associated with a diminished risk of PTSD symptoms (). In the adjusted Poisson regression analysis, severe and moderate TBI remained associated with a diminished risk of PTSD symptoms relative to the no-TBI comparison group (). Severe facial and spinal cord injuries were also associated with an increased risk of PTSD symptoms (). In this adjusted analysis, ISS was not associated with the development of PTSD (RR, 1.00; 95% CI, 0.99-1.01).
Associations Between TBI Subtype, Other Bodily Injury, and PTSD Symptoms 12 Months After Hospital Admissiona,b
The mean (SD) initial admission GCS score was 10.3 (9.6) for patients with severe TBI, 12.7 (7.3) for patients with moderate TBI, 13.6 (5.9) for patients with mild TBI, and 14.3 (4.6) for patients with no TBI. In analyses that adjusted for demographic and clinical characteristics, these comparisons achieved statistical significance (F3,68=57.0, P<.001). In univariate (RR, 0.99; 95% CI, 0.95-1.01) and multivariate (0.99; 0.97-1.01) analyses, lower GCS score was not associated with a diminished risk of PTSD.
Across TBI subgroups, in univariate analyses patients with symptoms consistent with a diagnosis of PTSD demonstrated clinically and statistically significant reductions in SF-36 subscale scores relative to patients with no PTSD (). Most of these associations remained significant in regression models that adjusted for relevant demographic and clinical characteristics ().
PTSD and Health and Cognitive Function Across Categories of TBI Severity Among 2993 Injured Patientsa
Patients with the most severe head injuries demonstrated the lowest cognitive scale scores as well as more gradual cognitive improvements during the year after injury (). Repeated-measures mixed-model regression analyses with 3- and 12-month cognitive scale scores as the dependent variable demonstrated a significant main effect for severe (β=−8.34, SE=1.11, P<.001), moderate (β=−5.69, SE=1.15, P<.001), and mild (β=−2.06, SE=1.09, P=.06) head injuries relative to the no-TBI comparison group.
Cognitive scale score by traumatic brain injury (TBI) category at 3 and 12 months after injury.
At the 12-month postinjury time point, regardless of TBI severity, patients with PTSD consistently demonstrated significantly lower cognitive scale scores (all P<.001) relative to patients without PTSD (). Adjusted regression analysis identified a significant association between PTSD and lower cognitive scale scores in the severe TBI (β=24.20, SE=5.50, P<.001), moderate TBI (β=16.25, SE=5.68, P=.01), mild TBI (β=15.34, SE=4.70, P=.002), and no TBI (β=22.09, SE=1.52, P<.001) subgroups.
Twelve-month posttraumatic stress disorder (PTSD) and cognitive scale scores across categories of traumatic brain injury (TBI).
Sensitivity analyses that used a continuous PCL score and an alternative PCL dichotomous cutoff of 45 or greater83
instead of PTSD diagnostic screening criteria did not substantially alter the magnitude, pattern, or significance of the associations between TBI subgroup, PTSD, and functional outcomes (ie, the results presented in , , and ). Also, analyses that excluded all interview data obtained by proxy did not substantially alter the magnitude, pattern, or significance of the observed associations between TBI subgroup, PTSD, and functional outcomes.