Journal of Head Trauma Rehabilitation:
TBI in the Military
Caregiver Reports of Subsequent Injuries Among Veterans With Traumatic Brain Injury After Discharge From Inpatient Polytrauma Rehabilitation Programs
Carlson, Kathleen F. MS, PhD; Meis, Laura A. PhD; Jensen, Agnes C. BS; Simon, Alisha Baines MS; Gravely, Amy A. MA; Taylor, Brent C. PhD; Bangerter, Ann BS; Schaaf, Katy Wilder PhD; Griffin, Joan M. PhD
Section Editor(s): Caplan, Bruce PhD, ABPP; Bogner, Jennifer PhD, ABPP
Portland Center for the Study of Chronic, Comorbid Mental and Physical Disorders, Portland VA Medical Center and Department of Public Health and Preventive Medicine, Oregon Health and Science University, Portland, Oregon (Dr Carlson); Center for Chronic Disease Outcomes Research, Minneapolis VA Health Care System, Minneapolis, Minnesota (Drs Meis, Taylor, and Griffin and Mss Jensen, Simon, Gravely, and Bangerter); Division of Epidemiology and Community Health, University of Minnesota School of Public Health, Minneapolis, Minnesota (Dr Taylor); Department of Medicine, University of Minnesota Medical School, Minneapolis, Minnesota (Drs Meis, Taylor, and Griffin); and Department of Physical Medicine & Rehabilitation, Neuropsychology & Rehabilitation Psychology Service, Virginia, Commonwealth University, School of Medicine, Richmond, Virginia, and Hunter Holmes McGuire VA Medical Center, Richmond, Virginia (Dr Schaaf).
Corresponding Author: Kathleen F. Carlson, MS, PhD, Portland Center for the Study of Chronic, Comorbid Mental and Physical Disorders, Portland VA Medical Center (R&D 66), 3715 SW US Veterans Hospital Road, Portland, OR 97239 (firstname.lastname@example.org).
This work was supported by grants from the Veterans Health Administration Health Services Research and Development Service (SDR 07-044; CDA 08-025). The opinions expressed in this article are those of the authors and do not necessarily reflect the position or policy of the Department of Veterans Affairs or the United States government.
The authors thank the Veterans of Operations Enduring Freedom and Iraqi Freedom, and their caregivers, for their service to the United States, and those who participated and shared their experiences for this study.
The authors declare no conflicts of interest.
Objective: We examined prevalence of, and potential risk factors for, nonfatal injuries among Veterans with traumatic brain injury (TBI) postdischarge from Veterans Affairs inpatient polytrauma rehabilitation programs.
Methods: We surveyed caregivers of patients who had military service anytime from 2001 to 2009, sustained polytrauma including TBI, received Veterans Affairs inpatient care from 2001 to 2009, were discharged at least 3 months before the study, and were alive when the study was fielded about caregiver and patient health, including patients' medically treated “accidents/new injuries” since discharge. We examined prevalence and source(s) of subsequent injuries and estimated patients' injury risk in reference to hypothesized risk factors. Odds ratios and 95% confidence intervals were calculated using multivariate logistic regression.
Results: Caregivers reported that nearly one-third (32%) of patients incurred medically treated injuries after discharge; most were associated with falls (49%) and motor vehicles (37%). Odds of subsequent injury were associated with select demographics, initial injury characteristics, and postdischarge health and functioning. Characteristics of caregivers, including physical and mental health, were also associated with patients' odds of subsequent injury.
Conclusions: A significant number of caregivers reported subsequent nonfatal injuries among patients treated for TBI/polytrauma in inpatient rehabilitation settings. Enhanced injury prevention efforts may be beneficial for this population.
COMPARED TO THE GENERAL POPULATION, trauma survivors have increased age-adjusted mortality rates for more than 20 years after hospital discharge for the initial trauma.1 Subsequent unintentional and intentional injuries are associated with the majority of these excess deaths.1,2
Cognitive, emotional, and/or physical sequelae associated with traumatic brain injury (TBI) may leave individuals especially vulnerable to subsequent injury. Prior studies have shown 3-fold excess injury mortality rates among survivors of TBI compared to the general population.3 However, injuries resulting in death usually comprise only a small proportion of all injuries incurred by a given population.4 While, in recent years, there has been a growing literature examining risks of nonfatal subsequent injury among individuals who have experienced other types of traumatic injuries,5–8 there has been little research examining nonfatal injury risk in the relatively large population of survivors of TBI. To provide the best care and to optimize the quality of life for patients who have survived TBI, interventions based on an empirical understanding of both incidence and risk factors for subsequent injuries are needed.
To help care for US Military Service Members and Veterans who have sustained complex, traumatic injuries in Afghanistan and Iraq, the US Department of Veterans Affairs (VA) Veterans Health Administration established 4 regional inpatient Polytrauma Rehabilitation Centers.9 A previous study showed that nearly all (97%) of the combat-injured service members and Veterans receiving care in the Polytrauma Rehabilitation Centers have sustained TBIs in combination with other physical and psychiatric insults.10 We conducted a study involving caregivers of patients with TBI who were discharged from these centers to (1) estimate the prevalence of postdischarge (subsequent) nonfatal injuries among patients with TBI/polytrauma and (2) identify potential risk factors for subsequent injuries that could be used to target pre- or postdischarge prevention programs for those patients at greatest risk.
This study is based on data from the Family and Caregiver Experiences Study, which was conducted between June and December of 2009 to assess needs and outcomes among caregivers of patients treated in one of the 4 VA Polytrauma Rehabilitation Centers.11 Study protocols, including waivers of documentation of informed consent, were reviewed and approved by the institutional review boards at all 4 Polytrauma Rehabilitation Center Sites. Using medical records, we identified next-of-kin for 1045 patients who (1) had served in the military anytime between September 2001 (the beginning of the conflict in Afghanistan) and February 2009, (2) sustained polytrauma that included TBI, (3) received inpatient care from any one of the 4 Polytrauma Rehabilitation Centers between September 2001 and February 2009, (4) had been discharged from inpatient care to either an institution or a community setting at least 3 months prior to the study, and (5) were alive at the time the survey was fielded (28 patients had died since Polytrauma Rehabilitation Center discharge; cause of death was not available for these patients). Response rates and caregiver and patient characteristics are presented below in the “Results” section.
The patients' next-of-kin were mailed a pre-notice letter 5 days before the survey packet was sent. The survey packet included an introductory letter, questionnaire, postage-paid return envelope, and $20 cash incentive. Follow-up contacts included a second mailing (without incentive) via overnight mail service to those not returning a questionnaire within 20 days of the first mailing, and 2 reminder telephone calls to nonresponders at days 15 and 35. The designated next-of-kin was also given the opportunity to nominate a more appropriate caregiver. Nominated caregivers received equivalent mailings, incentive, and follow-up. If desired, caregivers were allowed to respond to a shortened survey by telephone, which collected select information pertinent to their caregiving experiences.
Caregivers completed a survey that asked about both the caregiver and the patient. This information was supplemented when possible by data available in VA administrative databases. Because this study is the first to our knowledge to explore the issue of subsequent nonfatal injury among patients with TBI, our team developed a conceptual model (Fig. 1) to help guide study conceptualization and analysis. This model depicts theorized associations between groups of potential risk/protective factors and subsequent injury, with emphasis on variables that might be identifiable or modifiable from a clinical setting. Briefly, these groups of variables included (1) patient demographics (eg, gender, age), (2) characteristics of the initial TBI/polytrauma (eg, injury source, injuries/problems sustained), (3) characteristics of the patients' caregivers (eg, caregiver physical and mental health), and (4) patients' postdischarge health and functioning (eg, general health, ongoing symptoms/health problems). For visual clarity, hypothesized associations between individual variables are not depicted.
Main outcome (dependent) variables
We asked caregivers to report whether the patient had sought medical attention for 1 or more “accidents/new injuries” since discharge from a VA Polytrauma Rehabilitation Center. For affirmative responses, caregivers were asked to report the source(s) of subsequent injury and whether or not treatment for the injury or injuries was obtained at a VA facility. Cross-validation of caregivers' injury reports with VA medical records data was not done given that, as reported on the survey, a large proportion (∼25%) of patients were currently receiving their health care exclusively outside of the VA health care system (eg, private system or Department of Defense hospitals and clinics). In addition, as identified in the survey results, patients incurring subsequent injuries may be treated at the nearest urgent care, emergency department, or other setting, rather than a VA facility.
Patient demographics were collected from both the survey (military branch; education prior to initial TBI/polytrauma) and VA administrative data (gender, age, race/ethnicity).
Characteristics of the initial TBI/polytrauma were ascertained from both the survey (source of TBI/polytrauma, length of loss of consciousness, injuries/problems sustained) and administrative data (date of discharge from inpatient rehabilitation, discharge FIM® [previously referred to as Functional Independence Measure] ratings, TBI severity). Severity of the initial TBI was estimated on the basis of caregivers' reports of patients' length of loss of consciousness (LOC) at the time of the initial TBI/polytrauma. Responses were categorized to represent the following TBI severity levels: mild TBI (≤30 minutes LOC), moderate TBI (>30 minutes to <7 days LOC), and severe TBI (≥7 days LOC). A random sample of 24% of caregivers' LOC reports showed 79% consistency between caregivers' responses and medical records information indicating TBI severity when the categories of moderate and severe TBI were collapsed (available medical records data were not specific enough to consistently differentiate moderate from severe TBI). For the approximately 21% of caregivers who reported they did not know patients' LOC status, we then supplemented caregivers' reports with information from the patients' medical records. We considered this combined variable a rough indicator of TBI severity.
Caregivers were asked to identify which, from a list of 7 injury types frequently associated with TBI/polytrauma (fractures, amputations, burns, wounds, facial injuries, internal organ injuries, and spinal cord injuries) were sustained by the patient. The FIM® is an instrument commonly used to assess functioning in inpatient rehabilitation settings. The FIM® instrument includes 18 items that range from 1 (indicating the patient requires total assistance or “performs less than 25% of the task”) to 7 (patient is completely independent), with total scores ranging from 18 to 126. Research has indicated that 2 FIM® instrument subdomains can be derived from the overall instrument: cognitive (5 items) and motor (13 items).12 We used FIM® ratings assessed for all patients at the time of discharge. Because scores tended toward the higher (ie, more functional) end of possible ranges, we categorized cognitive, motor, and total FIM® ratings by quartiles, to the extent possible, to compare more functional to less functional patients.
Postdischarge characteristics of the patients and caregivers were assessed in the survey. Caregivers indicated their own and the patients' current health status based on a single question (“In general, would you say your [or your care recipient's] health is...?”) with a 5-point response scale ranging from “poor” to “excellent.” This question was adapted from the Veterans RAND 36 Item Health Survey.13 Caregivers were also asked to identify patients' ongoing symptoms related to the initial injury or treatment from a list of 16 frequently endorsed items (listed in Table 2). They also reported the number of hours of care they provided to the patient per week, and patients' current living arrangements, marital status, and needed functional assistance as measured through activities of daily living (ADLs) and instrumental activities of daily living (IADLs) with which the patient received help. Activities of daily living refer to the basic tasks of everyday life such as eating, bathing, dressing, toileting, and transferring14 while IADLs refer to self-care tasks performed at a higher level of functioning, such as shopping, performing housework, and preparing meals.15
TABLE 2-a Odds of ca...Image Tools
We assessed caregivers' mental and physical health using the PROMIS (Patient-Reported Outcomes Measurement Information System) v1.0 short forms for anxiety, depression, and physical functioning (see www.nihpromis.org for more information). The physical functioning scale included items assessing caregivers' ability to do chores, get dressed, bathe, and use the toilet. For respondents who completed at least two-thirds of scale items, PROMIScore software was used to generate respondent t scores that were standardized to the US general population such that a score of 50 represents the population mean with standard deviation (SD) of 10. Caregivers' scores were categorized to represent those within, above, or below 1 SD of the US mean. Respondents who completed less than two-thirds of PROMIS scale items were considered to have missing data for that scale. Caregivers also provided information on their own drinking and smoking based on items from the Behavioral Risk Factor Surveillance System.16 We measured quality of the relationship between patients and their caregivers using a single question (“Generally, how well do you and your care recipient get along?”) with responses ranging from “not well at all” to “very well.”
We conducted descriptive analyses on characteristics of the patients, their initial TBI/polytrauma, and the prevalence and source(s) of subsequent injury. To examine the potential for nonresponse bias, we compared survey respondents with nonrespondents by patient-related variables available in VA administrative data (gender, age, race/ethnicity, and FIM® ratings).
We used bivariate and multivariate logistic regression to examine hypothesized risk and protective factors for subsequent injury in this population. All potential risk and protective factors were analyzed as categorical variables. As indicators of polytrauma complexity, we additionally analyzed the number of initial concomitant injuries and ongoing symptoms/health problems as 2 continuous variables.
Multivariate regression models were specified on the basis of causal modeling and directed acyclic graphing methods developed by Greenland et al17 and demonstrated by Hernán et al.18 Our conceptual model (Fig. 1) was developed a priori and included a general framework depicting how hypothesized constructs may be associated with reinjury. The causal model (not shown), based on the conceptual model, was more complex and detailed hypothesized associations using unidirectional arrows between each variable of interest. The causal model was then used to develop directed acyclic graphs, a method to identify covariates that should be included in each statistical model. This method of covariate selection identifies more parsimonious analytical models than alternative approaches by tailoring covariate sets for each regression model through omission of covariates that may introduce bias or that are not anticipated to theoretically behave as a covariate for a specific analysis. To estimate risk of injury, we calculated odds ratios with 95% confidence intervals in reference to each hypothesized risk factor while controlling for potential confounders identified a priori from the directed acyclic graphs. This procedure was repeated for each separate independent variable, resulting in different sets of covariates being included in different models. Covariates included in each model are identified in the table footnotes.
There were 1045 patients discharged from VA Polytrauma Rehabilitation Centers between September 2001 and February 2009. We were unable to reach 208 next-of-kin by mail or phone. Of the 837 we could contact, 47 refused participation and 18 nominated an alternative contact as the patient's primary caregiver. A total of 564 caregivers completed a survey (67% of those we contacted; 54% of all unique patients' caregivers). We found no significant differences (P < .05) in patient demographics of the survey respondents versus nonrespondents across the administrative data examined.11
Most frequently, survey participants were parents (62%) or spouses/romantic partners (32%) of the patients. Patients were primarily male (95%) and in the Army (55%) or Marines (22%) at the time of their initial TBI/polytrauma. Patients ranged in age from 20 to 55 years (mean = 30.5; SD = 7.1). As is common in VA administrative data,19 race/ethnicity data were missing for a high proportion (∼40%) of the study population. Of those for whom data were available, the majority were identified as white (85%) and non-Hispanic (92%).
Nearly equal proportions of patients had incurred their initial TBI/polytrauma in the Middle East (Iraq, Afghanistan, or other Middle Eastern country; 48%) or the United States (45%); the remaining 7% were injured in various other overseas locations. The mean length of time since the initial TBI/polytrauma was 52 months (SD = 26). Initial injuries were most frequently associated with blasts or bullets and shrapnel (43%) or motor vehicles (43%). On the basis of the combined measure of TBI severity, 30% of patients were considered to have incurred mild TBI, while 70% incurred moderate/severe TBI.
Patients' discharge FIM® ratings tended toward the maximums (means/medians = 28.8/31.0, 80.5/89.0, and 109.3/119.0, respectively, for cognitive, motor, and total FIM® ratings), although scores ranged from the minimum to maximum possible for each. At the time of the survey, a large proportion (43%) of caregivers reported they currently provided fewer than 5 hours of care per week for the patient. However, nearly one-fourth provided 40 or more hours of care per week.
Reported subsequent injuries
Caregivers who opted to respond to the shortened telephone survey (n = 26) were not asked about patients' subsequent injuries and were thus excluded from further analysis. An additional 6% (n = 34) of mailed survey respondents did not complete the subsequent injury question, leaving a total of 504 for analysis. Of these, 161 (32%) caregivers reported postdischarge, medically treated injuries among patients (Table 1). Falls (n = 79) and motor vehicles (n = 59) were the most frequent sources of subsequent injuries, associated with 49% and 37%, respectively, of the reported injuries. Assaults (16%), burns (12%), and poisonings or firearm-related injuries (10%) were also frequently endorsed categories. Multiple injury sources were reported for 35 patients. For those reporting subsequent injuries, 43% reported that VA care was sought for at least one of those injuries. By source-of-injury category, VA treatment was most commonly received for fall- and burn-related injuries (42% and 37%, respectively; data not shown).
In both bivariate and multivariate modeling, increased odds of caregiver-reported subsequent injury were associated with select patient demographics, injury characteristics, and current health and functioning variables (Table 2). Compared to male patients, the small proportion of female patients had approximately 4 and a half times the odds of sustaining a subsequent injury. Higher age (≥35 vs <25 years) appeared to be associated with odds of subsequent injury but did not reach statistical significance in either bivariate or multivariate models. We found no associations between caregivers' reports of subsequent injury and source of initial injury, our rough indicator of TBI severity, or discharge FIM® ratings.
In univariate and multivariate analyses, patients whose reported current general health was poor or fair were more likely to have incurred injuries following their discharge from inpatient rehabilitation than those with excellent, very good, or good health. Patients requiring assistance performing ADLs or IADLs had significantly greater odds of injury than those who did not require assistance. Compared to patients who were married or living with a romantic partner, those who were divorced, separated, or widowed had elevated odds of subsequent injury in bivariate models; however, this association was not significant in the multivariate models. While the overall number of patients was low (n = 15), those who lived in assisted living or nursing homes had more than 4 times greater odds of injury than those living in a private residence.
Select initial concomitant injury types and ongoing symptoms and health problems, as endorsed by caregivers, were associated with odds of subsequent injury. Of the list of 7 injury types associated with the initial TBI/polytrauma, only spinal cord injuries were associated with caregivers' reports of subsequent injury. When analyzed as a continuous variable, the number of initial concomitant injuries endorsed by caregivers was not significantly associated with patients' odds of subsequent injury. Patients' ongoing symptoms/health problems were associated with odds of subsequent injury in both bivariate and multivariate models. At the bivariate level, patients for whom vision loss, chronic pain (other than headaches), balance or vestibular changes, depression, anxiety, anger problems, and sleep problems were endorsed had greater odds of subsequent injury. After controlling for potential confounders, vision loss, hearing loss, problems with speech, chronic pain (other than headaches), and depression appeared to be important risk factors for injury. When analyzed as a continuous variable, the number of ongoing symptoms/health problems also contributed to injury odds. After controlling for potential confounders, each additional item endorsed was associated with a 14% increase in the patients' odds of subsequent injury (odds ratio = 1.14; confidence interval = 1.06–1.22).
Some characteristics of the patients' caregivers were also associated with patients' odds of subsequent injury. In both bivariate and multivariate models, caregivers who reported their own health as poor or fair were more likely to report subsequent injuries for patients than caregivers who reported their own health as excellent, very good, or good. Similarly, caregivers with higher than average or average depressive symptoms or higher than average or average anxiety symptoms were more likely to report subsequent injuries among patients for whom they provided care than caregivers with lower than average scores on each scale. In bivariate models, caregivers with average or lower than average physical functioning scores had higher odds of reporting subsequent injuries among patients than those with higher than average physical functioning. In multivariate models, only those with lower than average physical functioning scores were more likely to report subsequent injuries among patients.
Our study is the first to examine subsequent nonfatal injury as an outcome among Veteran patients with a history of TBI and polytrauma who have been discharged from specialized inpatient rehabilitation programs. Similar to past mortality studies,3 our results suggest a need for enhanced postdischarge injury prevention programs for this population.
Caregivers reported that nearly one-third of discharged patients had incurred subsequent, medically treated injuries, with falls being the most frequent source of injury. These findings were similar to those reported by Krause7 involving patients with SCI. In Krause's longitudinal study, more than one-fifth of patients had sought medical treatment for subsequent injuries in the year prior to the survey, the majority of which were associated with falls. These findings were not unexpected, given that fall risk factors, such as balance disorders, can be common among survivors of TBI and other trauma20–22 and were reportedly prevalent in our study population. Motor vehicles were also associated with a large proportion of subsequent injuries. Recent research has shown that, compared with normative population data, individuals with a history of TBI have higher traffic crash rates,23 and that this increased risk may be associated with slower responses to traffic hazards.24 While the details of motor vehicle-related injuries were not collected in our study, our findings suggest room for improvement in current driving assessment and rehabilitation among patients with TBI/polytrauma.
Some of our findings suggest that patients with poorer outcomes (eg, those requiring assistance with ADLs or IADLs; those living in institutional settings; those in poor/fair health; those with certain ongoing symptoms/health problems) have the greatest odds of subsequent injury. In fact, we found that the odds of subsequent injury increased as the number of reported ongoing symptoms/health problems increased. This finding is consistent with population-based research showing odds of residential injury to be directly related to the number of disabilities reported by study participants.25 We also expected to find that individuals with more severe injuries would have the greatest risk of subsequent injury. This appeared to be true in the case of patients who sustained SCI as part of their TBI/polytrauma, a finding that is consistent with past research.5–8 However, we found no association between injury odds and patients' FIM® ratings or TBI severity. The former null finding may be due to the fact that most patients' FIM® ratings were relatively close to the maximum values; the latter may be due to our inability to differentiate and compare moderate and severe cases of TBI to mild cases of TBI. We hope that future research will continue to examine these potential risk factors. Such injury characteristics, and ongoing symptoms/health problems, may be useful for identifying patients at greatest risk of postdischarge injury and tailoring interventions to address their needs. For example, active long-term follow-up, assessment, and treatment (eg, of depression or chronic pain symptoms) of patients after discharge from inpatient rehabilitation programs may result in decreased incidence or severity of subsequent injuries.
Our multivariate regression analyses identified vision loss, hearing loss, speech problems, chronic pain, and depression as potential risk factors for subsequent injury. Other ongoing symptoms/health problems, such as anxiety, balance problems, anger problems, sleep problems, mobility problems, and seizures, also appeared to be important but did not reach statistical significance after controlling for potential confounders. It is possible that these problems also increase patients' risk of subsequent injuries but were not identified as risk factors in the current study because of our relatively low number of participants. Overall, our findings are consistent with a variety of past studies linking sensory impairments, pain, depression, and disability to higher rates of nonfatal injury.25–29 It is therefore likely that injury-related impairments at least partially drive vulnerability to subsequent injuries in this population.
While ongoing impairments (eg, vision or hearing problems) may be important in the identification of those at greatest risk, it is also critical to direct attention toward potentially modifiable factors. Hospital- and clinic-based injury prevention counseling can be effective for some high-risk populations such as emergency department patients30 and children and adolescents.31 Similar to caregivers of pediatric patients, caregivers of adult patients with TBI/polytrauma tend to be integrally involved in the well-being of the patient11 and may be highly receptive to evidence-based injury prevention counseling and educational materials. Further research may be needed to identify best practices for the timing and delivery of information about injury risk to patients and caregivers.32 Environmental modifications are often considered the most effective injury prevention and control strategies33 and should be the focus of such communication about risk and prevention. It is possible that enhanced home safety assessments prior to and following discharge from acute rehabilitation could also reduce the incidence of subsequent injuries among community-dwelling patients with TBI/polytrauma. Further empirical research examining specific elements of patients' environments that put them at risk may be needed.
A unique finding in our study was that the self-reported health of the patients' caregivers (eg, physical health, depression symptoms, and anxiety symptoms) was associated with patients' odds of subsequent injury. There have been studies examining the effects of TBI on the well-being of patients' informal caregivers.34,35 However, with the exception of one recently published study,36 there has been little research examining effects of caregiver health on patient outcomes. Because our study was cross-sectional, it is not possible to determine the direction of causality between caregiver health and patients' subsequent injuries. However, our results suggest that caregivers in better health may impart some protective effect on patient health. This, in turn, suggests that family-centered care programs, such as the one recently implemented by the VA Polytrauma System of Care,37 and caregiver support programs initiated as part of the new US legislation to support Veterans' family caregivers (Public Law 111-163; the Caregivers and Veterans Omnibus Health Services Act of 2010) could indirectly improve patient outcomes through enhanced support and services for patients' caregivers.
Another unique finding in this study was the greatly increased odds of subsequent injury among female patients. This was a surprising result given that, across epidemiologic studies of injury, males are almost always found to have increased risk of injury compared with females.38–40 The small number of female patients in our study makes this finding highly preliminary; however, this result may indicate unique gender-related injury risk factors among patients with TBI/polytrauma. Future research is needed to replicate this finding and explore potential explanations.
In the current study, we did not collect information on patients' high-risk health behaviors such as alcohol or drug use. Krause7 identified both binge drinking and psychotropic prescription drug use as risk factors for subsequent injury among patients with SCI. Other studies have also identified alcohol and drug abuse as risk factors for subsequent trauma among hospitalized trauma patients.41 Future research should examine how these and other behavioral factors contribute to increased risk of injury among patients with TBI/polytrauma. Clinical trials have shown that alcohol counseling at the time of trauma hospitalization is highly effective in reducing subsequent trauma-related hospitalizations42; it is possible that similarly designed health behavior counseling could reduce injury risk among discharged patients with TBI/polytrauma.
The current study also did not ask caregivers to report the intentionality of patients' injuries. Some of the identified injuries, particularly those associated with firearms or poisonings, may have been acts of self-harm. Our study focused on nonfatal rather than fatal injuries; however, the mechanisms of nonfatal and fatal injuries are often similar. In previous mortality studies, patients with TBI have been shown to have increased risks of suicide compared with the general population.43–46 While this trend has not been consistent across studies,3,47 suicidal ideation is understood to be a common psychological sequelae of TBI.48 Thus, attention toward intentionality of subsequent injuries, whether fatal or nonfatal, in this population is warranted.
This study has several important limitations, including the lack of data on environmental or behavioral factors and injury intentionality as mentioned earlier. The cross-sectional nature of our study inhibits our ability to infer causality. For example, patients' reported poor or fair current health may have been a result of, rather than a risk factor for, subsequent injuries. Future longitudinal studies would help delineate injury risk factors from outcomes. The rate of participation in our study was 67%, which is consistent with response rates in other studies involving caregivers.49,50 While our nonrespondent analysis showed no significant differences between patients of responding versus nonresponding caregivers, suggesting less bias in our estimates, it is possible that response bias may have affected our results. We were also limited by our reliance on proxy (caregiver) responses for information pertinent to the patients' experiences, and the relatively long window of recall on which they were asked to report. Data on patients' initial injuries, such as the length of time patients had lost consciousness, and the incidence and details of subsequent injuries, may have been affected by these factors. In the context of patients who have suffered TBI, caregivers' proxy reports of injury details may be more reliable than patient self-reports if patients suffer ongoing cognitive limitations. In our data, we observed increased likelihood of caregiver reports of subsequent injury as the patients' time since discharge (ie, time at risk) increased, which we took as evidence of accuracy of these proxy responses. However, validation of injury reports against medical records would have further strengthened this evidence. We did not conduct a validity substudy with VA data given that a substantial proportion of injuries were treated in non-VA settings. In future studies, proxy and self-report responses should be validated against medical records when possible.
Our study is the first to our knowledge to highlight postdischarge nonfatal injury as a problem among patients who have been treated for TBI/polytrauma in inpatient rehabilitation settings. Our results build the case for future longitudinal research efforts to examine how patient health problems (ie, ongoing symptoms/health problems) as well as caregiver health problems (ie, depression, anxiety) may interact with environmental factors to place patients with TBI/polytrauma at risk for subsequent injury. Future longitudinal work should validate reports of medically treated injury, collect further details about injury events, and further assess potentially risky environmental and behavioral exposures among patients with TBI/polytrauma.
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caregivers; health services; rehabilitation; traumatic brain injury; trauma; injury
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