SINCE 2000, more than three-fourths of the estimated 314 000 traumatic brain injuries (TBIs) diagnosed among service members were classified as a concussion or mild TBI (mTBI).1 Symptoms of concussion typically resolve within the first 2 weeks.2 However, a small yet significant proportion of service members will experience persistent postconcussive symptoms (PPCSs). These symptoms, such as sleep disturbance3–5 and cognitive complaints,6 continue beyond 3 months; for some, the symptoms will persist for years postinjury. Therefore, there remains a significant need for the treatment of these symptoms.7
The treatment of service members with PPCSs is complicated by the unclear etiology of these symptoms. Initial self-reported PPCS severity is associated with a host of both injury-related and non–injury-related factors. These factors include comorbidities (eg, posttraumatic stress disorder [PTSD],8–10 depression,11,12 chronic pain13), severity of other physical injuries sustained,14,15 injury mechanism,16,17 misattribution of symptoms,18–20 preinjury psychosocial characteristics,21–23 and potential disability compensation.24–26 Those treating and managing these symptoms must consider that numerous studies have found that PPCSs attributed to mTBI are largely explained by PTSD, depression, and other factor(s).27–29 In fact, the majority of studies have found that service members with PTSD report significantly greater PPCSs,8,9,27,30,31 which are potentially due to an overall increase in generalized health concerns caused by exposure to traumatic war-related exposures.32 Among these service members, the overlap in symptoms between mTBI and PTSD is especially problematic for both evaluating the overall symptom burden and identifying an effective treatment of PPCSs.33
Because the etiology of PPCSs is multifactorial, many experts recommend a multidisciplinary treatment to address patient needs.7,34,35 However, among service members or veterans with PPCSs, there is limited published literature reporting the effectiveness of specific multidisciplinary treatment programs.36 For example, Walter et al36 reported symptom reduction among a small sample of veterans completing multidisciplinary residential treatment of comorbid PTSD and TBI of all severities. However, the effectiveness of multidisciplinary treatment among a large sample of active-duty service members receiving outpatient treatment of persistent symptoms attributed specifically to mTBI has not been evaluated to date. Other experts point out that there is a lack of empirical evidence regarding specific treatment modalities that are both efficacious and cost-effective.32,33,37 In addition, treatment in other settings such as a primary care treatment model has been proposed as a cost-effective and efficacious alternative. Thus, in the military mTBI population, the effectiveness of multidisciplinary treatment of PPCSs and the impact of comorbid PTSD must be adequately evaluated.
Therefore, to address the aims of the current study, we studied a sample of active-duty service members with mTBI treated at a single, large, outpatient military treatment facility (MTF). This study had 3 specific aims: (1) to describe the military mTBI patient population at a single large MTF; (2) to examine the change in self-reported persistent postconcussive and PTSD symptoms; and (3) to explore potential demographic-, injury-, and rehabilitation-related factors associated with symptom change. Because this study analyzed secondary data not designed and powered as an experimental study, all hypotheses were considered exploratory. The main exploratory hypotheses were that patients would report a significant reduction in postconcussive and PTSD symptoms following treatment. This study also had 3 other additional exploratory hypotheses: (1) patients would report a reduction in individual postconcussive and PTSD symptom impairment; (2) patients with comorbid mTBI and probable PTSD would report greater pretreatment PPCSs; and (3) after adjustment for pretreatment PPCS burden, posttreatment PPCS burden would be higher for patients with probable comorbid PTSD.
Human subjects, animal subjects, or safety considerations
This retrospective study was approved by the institutional review boards at Brooke Army Medical Center (BAMC; C2009.117d) and the University of Texas School of Public Health (HSC-SPH-14-0126).
Study population and study design
The study population comprised US service members with a diagnosis of mTBI who completed outpatient treatment at the BAMC TBI Clinic from 2008 to 2013. Patients were initially referred by their primary care manager to the BAMC TBI Clinic. As part of standard operating procedures, all individuals referred to the clinic completed self-report symptom questionnaires on a computer kiosk prior to their initial encounter with physical medicine and rehabilitation personnel (eg, physician, physician assistant, or nurse practitioner). Next, the assigned physical medicine and rehabilitation personnel (1) determined whether the patient had sustained a TBI using both a semistructured clinical interview38 and medical record review, (2) rated the severity of the TBI if it was present,38 and (3) made treatment recommendations. The treatment recommendations were based upon a symptom-based management approach consistent with the Veterans Affairs (VA) and Department of Defense Clinical Practice Guidelines for the Management of Concussion/Mild Traumatic Brain Injury.7
BAMC TBI Clinic personnel designed a variety of treatment programs to meet patient needs, including specialty treatment programs for patients with mTBI and separate treatment programs for those with severe/penetrating brain injury and/or other neurorehabiltiation issues. For patients with persistent symptoms associated with mTBI, a multidisciplinary treatment program was designed to include the following elements: cognitive rehabilitation; vestibular interventions; headache management; and integrated behavioral healthcare to address co-occurring psychiatric conditions such as PTSD, depression, and sleep disturbances. On the basis of the patients' individual symptoms, clinic personnel provided multidisciplinary mTBI treatment programming using a diverse, but individualized, combination of therapeutic techniques targeted to each patient's needs (see Table 1). The TBI Clinic staff included the following professionals: 4 medical specialists, 3 speech-language pathologists, 2 occupational therapists, a physical therapist and a physical therapist assistant, 2 psychologists, and a neuropsychologist.
For individuals receiving care within this multidisciplinary mTBI treatment program, the median length of outpatient treatment from initial intake to discharge was approximately 2 months. During that period, individuals participated with each indicated discipline concurrently, not in a serial fashion. The intensity of treatment across and within disciplines varied during the course of care, but the dosage was typically 1 hour per week of individual therapy for cognitive rehabilitation, behavioral health interventions, and occupational therapy. For those individuals receiving vestibular rehabilitation, the dosage ranged from once per week to up to 5 days per week. Medical personnel followed patients at regular intervals (every 2 weeks) to monitor symptoms, adjust medications, provide positive psychoeducational interventions (positive expectations of recovery), discharge from therapy subspecialties, and facilitate patient disposition.
With regard to length of treatment and discharge from the BAMC TBI Clinic program, multidisciplinary clinic staff met weekly to review progress and determine readiness for discharge. Length of treatment varied by individual, as this program was designed to be open-ended until the patient reported resolution of symptoms. The criteria for rehabilitation completion were self-report of improved functioning and/or discharge from all disciplines. Of note, although self-report of improved symptoms was a key criterion for discharge from the program, the medical provider ultimately made the final determination regarding when to discharge a patient from care. For example, following an initial encounter with a patient, a medical provider might have prescribed a medication to assist with sleep onset and referred the patient to other subspecialties (eg, Speech Therapy) within the TBI Clinic. The patient's progress was discussed each week by these subspecialists at team rounds, and the patient was discharged from these services accordingly. The patient would have remained active within the clinic and followed by the medical provider until discharged from the last subspecialty. Unless ongoing TBI-specific medical issues warranted continued treatment, the medical provider would then discharge the patient from all services within the TBI Clinic.
Only medical records from patients with a diagnosed mTBI who completed the multidisciplinary mTBI treatment program were included in the analyses. This was an outpatient treatment program, and it was possible for patients to either drop out before treatment was completed or simply not complete the posttreatment assessments. Of the 2502 TBI patients treated at BAMC from 2008 to 2013, 989 (39.5%) patients sustained an mTBI and were treated through the multidisciplinary mTBI treatment program (see Figure 1). A further 10 patients were excluded because of an unknown or missing specialty treatment track transition. Therefore, we were unable to determine whether these patients were in either the multidisciplinary mTBI treatment program of interest or a different specialty treatment program. Patients with burn injury and amputation (n = 74) were also excluded because these patients require a unique treatment plan to allow for co-occurring intensive burn care or amputation rehabilitation. Finally, 648 patients were excluded because they were missing initial (pretreatment; n = 11) and/or discharge (posttreatment; n = 637) assessments on the Neurobehavioral Symptom Inventory (NSI) and the PTSD Checklist–Military Version (PCL-M) necessary for pre- to posttreatment symptom evaluation. Therefore, the final analytic sample consisted of 257 mTBI patients completing the multidisciplinary mTBI treatment program. We used a 1-group pre- to posttreatment study design to examine both persistent postconcussive and posttraumatic stress symptom change.
We also performed additional analyses for the main hypotheses using multilevel models so that we could include all available patient data, which included patients with only pretreatment assessment scores. For these multilevel models, the final analytic sample depended on the pattern of missingness for each assessment. Among the 905 patients with nonburn injury and amputation with a known treatment track who were treated through the multidisciplinary mTBI treatment program, the final analytic sample of all available data for the NSI pre- and posttreatment assessments was 857 and 257 patients, respectively. The final analytic sample of all available data for the PCL-M pre- and posttreatment assessments was 903 and 272 patients, respectively.
In postdeployment populations, it can be challenging to determine whether or not individual symptoms (eg, headache) persisted consistently or intermittently from the time of injury until the time of presentation for care. With the exception of 1 patient, all patients were admitted to treatment more than a week after the injury date of their last reported mTBI (time from injury to evaluation: 1-5219 days). This patient still met our inclusion criteria as having persistent symptoms attributed to mTBI because the patient had prior self-reported concussions and persisting symptoms that predated the most recent concussive event. For the purpose of this research study, we operationally defined persistent PPCSs as any symptom that a subject attributed to his or her remote concussive event.
In this study, PPCSs were assessed with the NSI.39 The NSI is a 22-item self-report inventory of common PPCSs, with a higher score indicating greater symptom severity. On the basis of a recent factor analysis of the NSI using 3 different military samples,40 the following 3 domain-specific symptom clusters were identified: cognitive (range, 0-16); affective (range, 0-28); and somatic/sensory (range, 0-44). Global PPCSs refer to the total rating of self-reported symptoms across all 3 symptom clusters (range, 0-88). Pre- and posttreatment NSI scores were analyzed both (1) globally across all symptom clusters and (2) for each of the 3 symptom clusters.
Pre- and posttreatment individual PPCSs were also dichotomized on the basis of patient responses for each individual question on the NSI. For each symptom, patients reporting “moderate” to “very severe” symptom complaints were categorized as “impaired.” Patients reporting “none” to “mild” symptom complaints were categorized as “not impaired.” A recent psychometric study among a sample of Operation Enduring Freedom (OEF)/Operation Iraqi Freedom (OIF) veterans reported that the NSI had high internal consistency and moderate external validity.41
PTSD symptoms were assessed with the PCL-M.42 The PCL-M is a 17-item self-rated interval rating scale that asks about symptoms specific to stressful military experiences. The 17 items on the PCL-M capture 3 diagnostic criteria for PTSD in the Diagnostic and Statistical Manual of Mental Disorders (Fourth Edition, Text Revision): B- (reexperiencing; range, 5-25); C- (avoidance and numbing; range, 7-35); and D-item (hyperarousal; range, 5-25) symptom clusters.43 Global PTSD symptoms refer to the total rating of self-reported symptoms across all 3 symptom clusters (range, 17-85), with a higher score indicating greater symptom severity. Pre- and posttreatment PCL-M scores were analyzed both (1) globally across all symptom clusters and (2) for each of the 3 symptom clusters. Our sample included a variety of service members with combat deployments and potential multiple traumatic experiences. In completing the PCL-M, subjects were not instructed to focus on a specific reference trauma.
On the basis of patient responses to each individual question on the PCL-M, pre- and posttreatment individual PTSD symptoms were also dichotomized into 2 categories. For each symptom, patients reporting a “moderately” to “extremely” high frequency of symptom complaints were categorized as “impaired.” Patients reporting “not at all” to “a little bit” frequency of symptom complaints were categorized as “not impaired.” The PCL-M generally has strong reliability and validity.44,45
Categorical demographic variables were age, sex, and military rank. Rank data were collected using the following response options: junior enlisted soldiers (E1-E4); noncommissioned officers (E5-E9); and officers (commissioned or warrant). For generalized linear models, these data were further dichotomized as either (1) enlisted soldiers or (2) noncommissioned and commissioned/warrant officers. Age was dichotomized on the basis of the sample median (ie, ≤29 or >29 years) for generalized linear models. Abstracted data from patient electronic medical records did not have data on race/ethnicity, education, marital status, or military branch.
This study had 5 categorical injury-related variables: number of self-reported TBIs of all severities (single/multiple), number of self-reported deployments (none/single or multiple), probable PTSD at pretreatment evaluation (yes/no) based on pretreatment PCL-M scores, TBI mechanism (blast/nonblast), and geographic location of injury (Continental United States, Outside Continental United States, Afghanistan–OEF, Iraq–OIF). All service members injured in Iraq and Afghanistan were injured during OIF and OEF, respectively. Service members injured OCONUS were injured in any other location outside CONUS (eg, Hawaii, Germany, Italy). Geographic location of injury (Continental United States/Outside Continental United States and OEF/OIF) was dichotomized for generalized linear models. Patients had to meet 2 different criteria in order to receive a diagnosis of probable PTSD at pretreatment evaluation. First, patients had to rate at least (1) 1 B item (questions 1-5), (2) 3 C item (questions 6-12), and (3) 2 D item (questions 13-17) symptoms as “moderately” symptomatic or above (responses 3-5). Second, patients had to report a global PCL-M score of 50 or more.46
Continuous rehabilitation-related variables in this study were the time from the most recent self-reported mTBI to pretreatment evaluation (days) and length of treatment (days). The categorical variables were the total number of consults (single/multiple) for enrollment across either various levels of specialty care (eg, inpatient and various specialty clinics outside the TBI Clinic) prior to admission to the TBI Clinic or for patients who were admitted and discharged to the TBI Clinic on more than 1 occasion. For generalized linear models, time from mTBI to treatment evaluation and length of treatment were dichotomized on the basis of the median (ie, ≤157 or >157 days and ≤50 or >50 days, respectively).
The NSI and PCL-M interval rating scale summed global and domain-specific scores were considered to be normally distributed on the basis of descriptive plots and because of the central limit theorem where n ≥ 30.47 Descriptive plots revealed that both the time from most recent mTBI to pretreatment evaluation and length of treatment were heavily skewed to the right when measured continuously. Therefore, these variables were considered nonnormal when analyzed as a continuous variable and the median and interquartile range (IQR) were reported. The number and proportion of categorical variables were reported for the study patients. To evaluate differences between included and excluded patients in the study, the Wilcoxon-Mann-Whitney test was used to test for significant differences (P < .05) of continuous variables and the χ2 test was used to test for significant differences of categorical variables.
The main exploratory hypotheses were that patients would report a significant reduction in global and domain-specific postconcussive and PTSD symptoms following treatment at BAMC. Paired t tests were performed to test for mean differences in PPCS change (pretreatment assessment − posttreatment assessment) assessed by the NSI. The test statistic, P value, and Cohen d were reported for both the (1) global symptom score and the (2) domain-specific symptom cluster group scores. Paired t tests were also performed to test for mean differences in PTSD symptom change (pretreatment assessment − posttreatment assessment) assessed by the PCL-M. Again, the test statistic, P value, and Cohen d were reported for both the (1) overall symptom score and (2) domain-specific symptom cluster group scores.
For comparison, the same main exploratory hypotheses were tested with multilevel models using all available data by including scores for patients with only pretreatment assessments and both pre- and posttreatment assessments. These models used a random intercept with an unstructured covariance structure to model pre- to posttreatment scores within individual patients. The least squares mean estimates, test statistics, P values, and Cohen d were reported for both the (1) global symptom score and the (2) domain-specific symptom cluster group scores.
This study also had 3 other additional exploratory hypotheses: (1) patients would report a reduction in the proportion of moderate to very severe individual postconcussive (NSI item score range, 2-4) and PTSD (PCL-M item score range, 3-5) symptom impairment; (2) patients with comorbid mTBI and probable PTSD would report a greater global and domain-specific pretreatment PPCS burden; and (3) after adjustment for pretreatment NSI scores, posttreatment NSI scores would be higher for patients with probable comorbid PTSD. For each of the 22 individual questions on the NSI and 17 individual questions on the PCL-M, McNemar tests were performed to test for differences in the proportion of patients with pretreatment symptom impairment to the proportion of patients with posttreatment symptom impairment. To compare the symptom burden among patients with mTBI alone and patients with comorbid mTBI and probable PTSD, independent-group t tests were performed to test for differences in PPCSs both (1) pretreatment and (2) posttreatment. The test statistic and P value were reported for both the (1) global symptom score and (2) domain-specific scores. Equality of variance was assessed with an F test to determine whether either the Satterwaite test (unequal variances) or pooled t test (equal variances) was most appropriate.
Generalized linear models were performed to explore if reported least squares mean posttreatment NSI and PCL-M scores were different across individual dichotomous demographic-, injury-, and rehabilitation-related independent variables. The model assumption of normality of residuals was assessed with the Kolmogorov-Smirnov test. Homogeneity of regression slopes was assessed with an interaction term. If the P value for the interaction term was .05 or less, then regression slopes were not considered homogenous and the interaction term was retained in the model. For models identified with an interaction term, the least squares means were reported with varying pretreatment NSI and PCL-M scores. Among all exploratory hypotheses, there were 50 multiple comparisons assessing persistent symptoms with NSI scores and 37 multiple comparisons assessing persistent PTSD symptoms with the PCL-M. Therefore, the test-specific Bonferroni type I error-level adjustment to account for multiple comparisons was P < .001. All statistical analyses were performed on available data using SAS/STAT software, version 9.2, of SAS System for Windows (SAS Institute, Cary, North Carolina).
Patients excluded from the analyses reported a greater proportion of multiple TBIs (73.5% vs 61.5%; P = .003), fewer blast-related mTBIs (54.1% vs 61.9%; P = .03), a longer median time from injury to pretreatment evaluation (310 days vs 157 days; P = .001), and a shorter median length of treatment (43 days vs 50 days; P = .001) (see Table 2). Fewer excluded patients had 2+ consults (30.7% vs 37.4%, respectively, borderline significance; P = .05).
Study patients were predominantly male (89.1%); they were either noncommissioned or commissioned/warrant officers (58.7%); and the majority of patients were younger than 30 years (51.8%). Furthermore, the majority of patients reported the following injury-related characteristics: multiple TBIs (61.5%); multiple deployments (53.9%); a blast-related mechanism of mTBI (61.5%); and sustaining their most recent mTBI during OEF/OIF (77.8%). Approximately one-third (34.2%) of patients met the criteria for probable PTSD at pretreatment evaluation. The median time from injury to pretreatment evaluation was approximately 5 months (157 days; IQR = 47-573 days), and the median length of treatment was approximately 7 weeks (50 days; IQR = 32-83 days). In addition, the majority of patients had 1 consult (62.7%).
Patients reported a statistically significant (P < .0001) reduction in global and domain-specific (ie, affective, cognitive, somatic/sensory) PPCSs (see Table 3). Moreover, the effect size for global PPCS reduction was medium (d = 0.72) and the effect size for domain-specific symptom reductions were also medium (d = 0.59-0.68). Patients also reported a statistically significant (P < .0001) reduction in global and domain-specific (ie, reexperiencing, avoidance and numbing, hyperarousal) PTSD symptoms (see Table 4). The effect size for global PTSD symptom reduction was small (d = 0.34), and the effect sizes for domain-specific symptom reductions were small to medium (d = 0.25-0.48). The results and interpretation were similar for both the paired t tests and multilevel models.
With the exception of 1 affective symptom (ie, feeling sad or depressed) and 1 somatic/sensory symptom (ie, change in taste and/or smell), patients reported a significant reduction (P < .001) in impairment for all other individual PPCSs (see Table 5). Regarding PTSD symptoms (see Table 6), patients reported a significant reduction (P < .001) in all of the individual hyperarousal symptoms and all but 2 of the individual reexperiencing symptoms (ie, flashbacks and psychological reactivity). However, patients reported a significant reduction in only one of the individual avoidance and numbing symptoms (ie, foreshortened future).
Compared with patients with only mTBI at pretreatment evaluation, patients with comorbid mTBI and probable PTSD reported a statistically significant (P < .0001) higher PPCS burden during both pre- and posttreatment evaluations (see Table 7). On the basis of the generalized linear models, the only meaningful demographic-, injury-, or rehabilitation-related variable was a diagnosis of probable PTSD at pretreatment evaluation. Compared with patients who did not meet the criteria for probable PTSD at pretreatment evaluation, patients meeting the criteria for probable PTSD reported a significantly higher posttreatment PPCS burden (27.9 vs 21.7; P = .0009) (data not shown). Although PTSD treatment may not have been a primary focus of the treatment program, nearly one-third of patients (n = 75; 29.2%) reported a clinically meaningful resolution of PTSD symptoms48 (difference in pre- to posttreatment PCL-M score ≥10) (data not shown). This includes only half (n = 44; 50%) of the 88 patients with pretreatment probable PTSD. None of the other demographic-, injury-, or rehabilitation-related variables of interest predicting PCL-M score at posttreatment evaluation were statistically significant.
TBI mechanism (blast vs nonblast) was identified as a potential effect modifier based on a significant (P < .05) interaction term for both the NSI (P = .003) and PCL-M (P = .03) generalized linear models (see Table 8). As both the pretreatment NSI and PCL-M scores increased, the estimated posttreatment least squares mean NSI and PCL-M scores increased disproportionately for patients with nonblast injury compared with patients with blast injury.
The current study demonstrated that military patients with a self-reported history of an mTBI who completed multidisciplinary treatment reported a reduction in both persistent postconcussive and PTSD symptoms. Previous studies have examined the postconcussive and PTSD symptom burden attributed to mTBI using cross-sectional postdeployment surveys27,30,49; longitudinal surveys of recruited service members50,51; postdeployment trauma registries52; and patient records from military hospitals, VA Medical Centers, and outpatient clinics.9,41,53,54 Fewer studies36 have accomplished the following 3 goals: (1) described the patient population requiring treatment of persistent postconcussive and PTSD symptoms; (2) examined how these persistent symptoms change pre- to posttreatment; and (3) explored potential demographic-, injury-, and rehabilitation-related variables associated with persistent symptom change. To our knowledge, the current study was the first to address all 3 of these gaps by investigating these associations in a large military outpatient population at a major US MTF.
Because of the limited published literature on treatment outcomes among service members or veterans with PPCSs, the potential for comparing our findings with those from other studies is limited. The study by Walter et al36 was the only other identified study using a veteran sample that reported both pre- to posttreatment persistent postconcussive and PTSD symptom change. They reported findings for 28 veterans evaluated at a VA Medical Center with comorbid TBIs of all severities and PTSD. Similar to the treatment used in our study, the treatment in the study by Walter et al was multidisciplinary. Dissimilar from the treatment used in our study, this small group of veterans was treated in a residential treatment program with an intensive focus on PTSD treatment using CPT-C (Cognitive Processing Therapy Cognitive-Only). Walter et al reported that their treatment program reduced not only global persistent PTSD symptoms but also global PPCSs assessed by the NSI. This is likely due to the fact that PPCSs are not specific to mTBI, and these symptoms may be more similar to symptoms from the hyperarousal dimension of PTSD.55
After adjusting for pretreatment NSI score, PTSD symptoms were the only demographic-, injury-, or rehabilitation-related variable that were significantly associated with PPCS resolution. Again, results from the current study mirror results from the study by Walter et al,36 who found that PTSD symptoms were associated with both pretreatment PPCSs and pre- to posttreatment resolution. Many of the symptoms of PPCSs such as difficulty concentrating, sleep disturbance, and irritability are the same as those for PTSD.56 Therefore, in the context of a potentially life-threatening traumatic injury, this overlap in symptoms may be due to an increase in generalized health concerns caused by the dysregulation of both the autonomic nervous and neuroendocrine systems.32 Furthermore, this may explain why numerous studies have found that service members with PTSD report significantly greater PPCSs.8,9,27,30,31 Thus, PPCSs attributed to mTBI likely are at least partially, if not entirely, due to PTSD and/or other comorbid outcomes such as depression or chronic pain.11–13,57 Therefore, in the current study, patients with probable PTSD may have reported poorer PPCS resolution due to residual symptoms of comorbid probable PTSD. However, in both the current study and the study by Walter et al, patients may have reported a decrease in both PPCSs and PTSD symptoms as the result of completing a multidisciplinary treatment program that addressed both general PPCSs and more specific PTSD symptoms.
Mild TBI mechanism (blast vs nonblast) was identified as a potential effect modifier in both persistent PTSD and PPCS resolution. Compared with patients with a higher burden of pretreatment persistent symptoms and a non–blast-related mechanism of mTBI, patients with the same pretreatment burden of persistent symptoms but a blast-related mechanism of mTBI reported greater posttreatment symptom resolution. No previous studies specifically investigated the association between TBI blast mechanism and persistent symptom resolution; however, our finding is in contrast with other studies that explored the association between initial persistent symptom burden and blast mechanism and have found no significant difference.58–61 Thus, future studies are warranted to establish the true association between blast mechanism and persistent symptom resolution.
The only specific treatment method for PPCSs consistently associated with PPCS resolution/reduction in the literature is patient education.62–65 The primary focus of patient education is an explanation of the general mTBI pathophysiology, explanation of the typical sequelae, and reinforcing the patients' expectations of recovery.64 Expectation of recovery is a method for improving mTBI outcomes based on the knowledge that the vast majority of patients recover fully, and this expectation helps reduce the likelihood that symptoms associated with other comorbidities are misattributed to mTBI.18–20,66,67 Because expectation of recovery was a key component of the BAMC TBI Clinic treatment approach and the only treatment that all patients received, the self-reported symptom reduction in our study may be primarily attributed to this component of the therapy. However, experts have also suggested that since we do not know which components of treatment adequately manage PPCSs, symptom resolution may be at least partially facilitated by the healing treatment environment that provides social reinforcement and breaks from the stress of daily routines.37
We found that patients in our study who completed outpatient multidisciplinary mTBI treatment in our specialty TBI Clinic reported a modest resolution of global PPCSs. Although PTSD was not the primary focus of treatment for most patients, we also found that half of the mTBI patients with pretreatment probable PTSD reported a clinically meaningful resolution of PTSD symptoms. Although the specialty clinic model was established in MTFs relatively early during OEF/OIF (2008 at our facility), experts have since argued that most patients' symptoms may not require specialty intervention and that treatment in a primary care setting using a multidisciplinary collaborative care treatment model may be more cost-effective.7,32,65,68 They argue that a primary care treatment model reduces the disadvantages of lengthy and resource-intensive specialty clinic treatment programs that reinforce negative illness expectations, perpetuate symptom persistence caused by inconsistent clinical opinions from varying specialists, and increase lost work time.32,33 Additional research is needed to better understand the pros and cons of treatment of PPCSs in these settings.
There are limitations to the current study. First, this was an exploratory observational study that used retrospective data originally collected for clinical purposes and not for research. Thus, these findings suggest an association between treatment and symptom resolution but do not confirm a causal relationship. In addition, despite the test-specific Bonferroni type I error-level adjustment for multiple comparisons, it has been argued that a valid type I error level cannot be calculated for exploratory analyses because these analyses inherently provide an invalid estimate of sampling error that bias the external validity of results.69 Second, a large proportion of patients were excluded primarily because of missing posttreatment assessment data. While it may be that these assessments were missing because the patients spontaneously stopped treatment due to symptom resolution, it also remains highly plausible that individuals withdrew because of lack of improvement, frustration, or other negative treatment outcomes or were not afforded the opportunity for a discharge outcome measure because they did not self-identify as having improved. Excluded patients reported sustaining a greater number of TBIs70,71 and a longer time from injury to treatment evaluation,54 thus indicating that attrition of these patients may have been related to more severe persistent symptoms and/or a lack of responsiveness to the treatment. Future studies should attempt to quantify differences between these 2 groups of patients. We also excluded the small number of patients with burn injury and amputation from our study. Future studies with a more representative population of patients should investigate how the presence of these other injuries might influence symptom resolution. Third, although probable PTSD was assessed with a widely used self-report measure and we applied a conservative diagnostic criterion, we did not confirm that patients were actually exposed to a precipitating psychological trauma. As a result, we cannot specifically infer a diagnosis of PTSD or a relationship between PTSD and their concussive event. Fourth, many important variables of interest (eg, social support, education, military branch) were not collected and the actual treatments received were likely highly variable from patient to patient. Furthermore, because of the lack of specific detail on both the type and quantity of treatments administered, we were unable to evaluate the effectiveness of specific treatment modalities. Prospective studies on this topic should examine these specific treatments to elucidate which components of care provide optimal management of patient symptoms.
Rather than solely assessing the initial persistent mTBI symptom burden, evaluating the effectiveness of completing multidisciplinary outpatient treatment of persistent PPCSs is a strength of this study. Furthermore, this is the first study to provide a detailed description of a specific multidisciplinary outpatient treatment program administered at a large MTF. Unlike previous studies, this study was also able to compare persistent symptom resolution between patients with mTBI alone and patients with comorbid mTBI and probable PTSD. Because BAMC is one of the largest military medical centers the results may be applicable to other large military medical centers and VA hospitals that have similar patient complexity and staff competency.
To strengthen the evidence regarding specific aspects of this specialty treatment approach, many of the stated limitations can be addressed if future studies use a rigorous methodology with valid and reliable measures.72 This includes the systematic collection of clinical outcome data that can be used to provide information about which components of treatment may be associated with symptom reductions and lead to improved rehabilitation outcomes.73 By establishing a culture of systematically obtaining validated outcomes, clinics will be better equipped to provide quality scientific evidence in order to improve clinical practice, inform clinical practice guidelines, and ultimately provide patients with the most effective and innovative treatment.
The results from this study indicate that the multidisciplinary treatment approach implemented at BAMC TBI Clinic was associated with reduced self-reported persistent postconcussive and PTSD symptoms. This study could not determine whether outpatient multidisciplinary treatment approaches to mTBI care in a specialty clinic are either efficacious or cost-effective, and it is unknown whether the benefits of treatment outweighed the potential disadvantages. Further prospective studies designed to identify the components of specialty clinic treatment that specifically contribute to symptom reduction are needed in order to adequately evaluate this treatment approach. In addition, studies of symptom management using the collaborative care and step-care models in the primary care setting are also urgently needed to compare with findings from specialty clinics. This comparison will help inform the development of the most appropriate and cost-effective treatment approaches for service members and veterans with persistent PPCSs.
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Keywords:Copyright © 2017 Wolters Kluwer Health, Inc. All rights reserved.
blast injuries; mild traumatic brain injury; military personnel; posttraumatic stress disorder; rehabilitation; treatment