JOURNAL OF DUAL DIAGNOSIS, 11(1), 22–32, 2015 ISSN: 1550-4263 print / 1550-4271 online DOI: 10.1080/15504263.2014.989653

PSYCHOPHARMACOLOGY & NEUROBIOLOGY

PTSD and Substance Use Disorder Among Veterans: Characteristics, Service Utilization and Pharmacotherapy Adina Bowe, MD,1 and Robert Rosenheck, MD1,2

Objective: While there has been considerable concern about veterans with dually diagnosed posttraumatic stress disorder (PTSD) and comorbid substance use disorders, a national study of clinical characteristics, service utilization, and psychotropic medication use of such veterans in Veterans Affairs (VA) has yet to be conducted. We hypothesized that veterans having both PTSD and substance use disorder would have lower socioeconomic status, greater medical and psychiatric comorbidity, higher medical service utilization, and more psychotropic pharmacotherapy fills. Methods: National VA data from fiscal year 2012 were used to compare veterans with dually diagnosed PTSD and substance use disorder to veterans with PTSD without substance use disorder on sociodemographic characteristics, psychiatric and medical comorbidities, mental health and medical service utilization, and psychotropic pharmacotherapy. Comparisons were based on bivariate and Poisson regression analyses. Results: The sample included all 638,451 veterans who received the diagnosis of PTSD in the VA in fiscal year 2012: 498,720 (78.1%) with PTSD alone and 139,731 (21.9%) with dually diagnosed PTSD and a comorbid substance use disorder. Veterans with dual diagnoses were more likely to have been homeless and to have received a VA disability pension. Medical diagnoses that were more strongly associated with veterans with dual diagnosis included seizure disorders, liver disease, and human immunodeficiency virus (HIV). Psychiatric comorbidities that distinguished veterans with dual diagnoses included bipolar disorder and schizophrenia. Veterans with dually diagnosed PTSD and substance use disorder also had a greater likelihood of having had mental health inpatient treatment. There were no substantial differences in other measures of service use or prescription fills for psychotropic medications. Conclusions: Several substantial differences were observed, each of which represented more severe medical and psychiatric illness among veterans with dually diagnosed PTSD and substance use disorder compared to those with PTSD alone. However, effective treatments are available for these disorders and special efforts should be made to ensure that veterans with dual diagnoses receive them. (Journal of Dual Diagnosis, 11:22–32, 2015)

Keywords dual diagnosis, posttraumatic stress disorder, homeless, veterans

The Department of Veterans Affairs (VA) is the largest single provider of services to veterans in the United States. More than five million veterans were seen in the VA during fiscal year 2012; of these, almost two million had a psychiatric diagnosis of some kind, with 638,451 (34%) having posttraumatic stress disorder (PTSD). An increasing number of veterans returning from Iraq and Afghanistan, as well as from earlier wars, have sought help from the VA for PTSD in recent years (Gates et al., 2012; Hermes, Rosenheck, Desai, & Fontana, 2012; Pukay-Martin et al., 2012), and there has been mounting This article is not subject to U.S. copyright law. 1Department of Psychiatry, Yale Medical School, New Haven, Connecticut, USA 2VA New England Mental Illness, Research, Education and Clinical Center, West Haven, Connecticut, USA Address correspondence to Adina Bowe, MD, Department of Psychiatry, Yale Medical School, 932 Quinnipiac Ave., Apt 4, New Haven, CT 06513, USA. E-mail: [email protected]

concern about the well-being of these veterans, especially those with both PTSD and substance use disorders. A major study of Vietnam-era veterans conducted more than 20 years ago showed that veterans with PTSD had a substantially greater risk of substance use disorder than others who served during the Vietnam era (Kulka et al., 1990). This trend was recently confirmed in a 2009 study of VA administrative data showing that veterans with PTSD were three times more likely to have comorbid substance use disorder than adults in the general population (Petrakis, Rosenheck, & Desai, 2011). Studies of PTSD both in the VA and in the general population have suggested that individuals with dual diagnoses had more severe problems that those with PTSD alone (Ouimette, Brown, & Najavits, 1998; Kessler, Sonnega, Bromet, Hughes, & Nelson, 1995). Despite evidence that veterans with dually diagnosed PTSD and substance use disorder are likely to have more severe symptoms than those with PTSD alone, little has been

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published with respect to psychiatric and medical comorbidities and service use associated with these veterans. What little has been reported has not been entirely consistent. A small study by Tate, Norman, McQuaid, and Brown (2007) compared veterans with substance use disorder alone to those with substance use disorder and PTSD and found that among veterans with substance use disorder, those with dually diagnosed PTSD were significantly more likely to have cardiovascular and neurological diagnoses and greater total numbers of chronic physical symptoms in comparison to those with substance use disorder alone (Tate et al., 2007). A somewhat larger study, however, suggested that no significant interactions between substance use disorder and PTSD were detected for male or female veterans in rates of medical comorbidity (Nazarian, Kimerling, & Frayne, 2012). These studies did not determine whether there was an increased prevalence of psychiatric or medical comorbidity in veterans with dual diagnoses, as they did not specifically compare veterans with dually diagnosed PTSD and substance use disorder to those with PTSD alone. Data on common Axis I psychiatric comorbidities among veterans with dually diagnosed PTSD and substance use disorder are also sparse. A national study using VA administrative data found that among veterans with mental disorders, the rate of comorbidity with substance abuse is lower in veterans with PTSD than with several other mental disorders, in particular bipolar disease and schizophrenia (Petrakis et al., 2011). However, a national examination of the more common Axis I psychiatric comorbidities among veterans with both PTSD and substance use disorder as compared to those with PTSD alone has yet to be conducted. When considering medical and psychiatric comorbidities, it is reasonable to postulate that differences in comorbidity would translate to differences in service utilization and psychotropic medication use, which have also received limited attention. Veterans with PTSD have been found in one singlesite study to be more likely to use mental health services than veterans without PTSD and have longer lengths of inpatient stay, perhaps reflecting greater levels of psychological distress and dysfunction (Kramer, Booth, Han, & Williams, 2003). Veterans with psychiatric diagnoses, particularly PTSD, were found in one study to utilize significantly more VA medical services (Cohen et al., 2010), but again, veterans with dually diagnosed PTSD and substance use disorder were not specifically addressed. Thus, it is not clear whether those veterans with dual diagnoses have higher levels of service use than those with PTSD alone. Although there is evidence that veterans with both PTSD and substance use disorder experience more severe emotional problems than those with PTSD alone (Norman, Tate, Anderson, & Brown, 2007), no study has examined whether veterans with dually diagnosed PTSD and substance use disorder are prescribed more psychotropic medications than those with PTSD alone using a national sample. Research on prescription drug use in veterans with PTSD and substance use

disorder has, thus far, largely focused on opioids, benzodiazepines, and antipsychotics (Bauer et al., 2014; Hawkins, Malte, Imel, Saxon, & Kivlahan, 2012; Morasco & Dobscha, 2008; Sernyak, Kosten, Fontana, & Rosenheck, 2001; Whitehead et al., 2008). There has been considerable debate on the safety and efficacy of these drugs for veterans with PTSD, and one small study found PTSD to be associated with an increased likelihood of medication underuse, abuse, and treatment non-adherence in different patients (Lockwood, Steinke, & Botts, 2009). Prescribing trends, especially benzodiazepine use, have been evaluated in national VA studies, but these studies focused on all veterans with PTSD and not specifically on those with dual diagnoses (Abrams, Lund, Bernardy, & Friedman, 2013; Lund, Abrams, Bernardy, Alexander, & Friedman, 2013). Veterans with PTSD frequently receive medications not recommended for people with this disorder, including atypical antipsychotics in both male and female veterans and benzodiazepines in female veterans with PTSD (Bernardy et al., 2013). Bauer et al. (2014) evaluated factors that were associated with off-label atypical antipsychotic use in veterans with PTSD and found that having a diagnosis of substance use disorder increased the likelihood of being prescribed these medications. Such use of psychotropic medications without specific justification may pose important side effect risks (for example metabolic syndrome) in the absence of evidence of outcome benefits. In the present study, national VA administrative data from fiscal year 2012 were used to compare veterans with PTSD alone with veterans with dually diagnosed PTSD and either alcohol or drug use disorders using both bivariate and multivariate Poisson regression analysis to evaluate differences in sociodemographic characteristics, Axis I psychiatric and medical diagnoses, mental health and medical service utilization, and psychotropic pharmacotherapy fills. We thus seek to examine the distinctive correlates of comorbid substance abuse among veterans receiving treatment for PTSD in a national clinical sample. By identifying differences in those characteristics, it may be possible to better tailor services to meet the specific needs of these veterans. We hypothesize that veterans having both PTSD and substance use disorder will have lower socioeconomic status, greater medical and psychiatric comorbidity, higher medical service utilization, and more psychotropic pharmacotherapy fills.

METHODS Sample The sample included all 638,451 veterans with PTSD diagnosed in the VA in fiscal year 2012 across all medical centers. Subjects were categorized into two groups, those with PTSD alone (n = 498,720, 78.2%) and those with PTSD and 2015, Volume 11, Number 1

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substance use disorder (n = 139,731, 21.8%). Of those with substance use disorder, 64,348 (46.1%) had an alcohol use disorder alone; 34,949 (25.0%) had a drug use disorder alone, and 40,434 (28.9%) had both. Substance use disorders were diagnosed using DSM-IV-TR clinical criteria and included both substance abuse and substance dependence.

Measures Sociodemographic characteristics included age, receipt of service-connected disability compensation, receipt of VA disability pension, gender, rural versus urban residence, and income. Service-connected disability compensation is a monthly payment made to a veteran who has a disability from a disease or injury that was incurred or aggravated by service in the armed forces. The amount of compensation increases with the severity of the disability, based on a rating of the percentage of disability. VA disability pensions are monthly payments that are awarded to veterans who were honorably or medically discharged, served during a wartime era, have a limited income, and are permanently and totally disabled or at least 65 years old. Diagnostic measures included comorbid medical and psychiatric Axis I diagnoses. Measures of service use addressed outpatient medical and psychiatric services as well as mental health inpatient treatment. Pharmacotherapy measures assessed psychotropic prescription fills. Homelessness was also assessed using codes representing use of specialized services for homeless veterans or having a V60 (homelessness) code based on the International Classification of Diseases, Ninth Revision (ICD-9). Veterans were also categorized as having been deployed in support of operations in Iraq and/or Afghanistan based on a database obtained through collaboration with the Department of Defense. Urban versus rural location was classified into four categories by ZIP code using rural urban commuting area codes based on the ZIP code of residence (Morrill, Cromartie, & Hart, 1999). Clinical diagnoses included medical, psychiatric, and substance abuse diagnoses and were identified by ICD-9 codes in VA administrative data. Overall medical comorbidity was assessed using the Charlson Comorbidity Index (Charlson, Pompei, Ales, & MacKenzie, 1987). The Charlson Comorbidity Index assesses severity of medical status by weighting selected diagnoses that together are predictive of mortality over a five-year period. This index has been widely utilized by health researchers to measure burden of disease and medical case mix (Needham, Scales, Laupacis, & Pronovost, 2005; Quan et al., 2011). The Charlson Comorbidity Index was also used to identify common severe non-psychiatric illnesses, which were examined individually, along with an array of ICD-9 pain diagnoses. Tobacco use was not examined in this study. The number of VA outpatient primary care, specialty medical-surgical, general psychiatric, substance abuse, and Journal of Dual Diagnosis

emergency department visits in fiscal year 2012 were recorded using relevant clinic stop codes. Psychotropic medication prescriptions were classified in six groups including antidepressants, antipsychotics, anxiolytics/sedative hypnotics, stimulants, mood stabilizers, and lithium (specific medications included in each group are available on request). Measures addressed the number of prescriptions filled in each class and in all classes together at VA pharmacies during the entire fiscal year.

Analysis Bivariate analyses compared veterans with PTSD and substance use disorder versus those with PTSD alone on sociodemographic characteristics, medical and psychiatric comorbidities, service use, and psychotropic medication fills. Due to the large sample representing the entire population of VA service users and the resultant extreme statistical power, effect sizes were the focus of statistical analysis rather than alpha values. When examining effects using large samples, significance testing can be misleading because even small or trivial effects are likely to produce statistically significant results. Cohen’s d was calculated for continuous variables (difference in means divided by the pooled standard deviations) and risk ratios for categorical variables to reflect the magnitude of the association of each patient characteristic with comorbid PTSD and substance use disorder. In Statistical Power Analysis for the Behavioral Sciences, Cohen (1988) outlined criteria that are now widely accepted for gauging small, medium, and large effect sizes on continuous variables. For this reason, a moderate effect size of 0.5 was chosen as the cutoff for significance for Cohen’s d. In terms of effect size quantification for risk ratios, consistent with Ferguson (2009), we have identified values greater than 2 or less than 0.5 as practically significant effect sizes for dichotomous values. A risk ratio of 2.0 would indicate that the “control” group is twice as likely to demonstrate a given condition as the “treatment” group. A risk ratio of 1.0 indicates no difference in risk between the two groups. Below 1.0 indicates less risk for the control group than the treatment group. However, as argued by Ferguson, risk ratio values between 1.0 and 2.0 are unlikely to have much practical clinical meaning and are likely to be unreliable and contradictory across studies (Ferguson, 2009). Dichotomous variables that had risk ratios greater than 2.0 or less than 0.5 and continuous variables with Cohen’s d above 0.5 (moderately large effect size) were considered to have a substantial relationship to dual diagnosis. In addition, because variables with large base rates are likely to have smaller effect sizes, these variables were examined and those with substantial risk differences (simple difference in proportions) of more than 15% were also considered to have substantial effects. These variables are indicated by asterisks in Table 1. For those variables that were found to have substantial associations in terms of risk ratio or Cohen’s d, as well as for several

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PTSD and Substance Use Disorder Among Veterans

TABLE 1 Bivariate Analysis of Veterans With PTSD, With and Without Substance Use Disorder (N = 638,451) PTSD Alone (n = 498,720) DEMOGRAPHICS Age (years) Income Gender (male) Race White Black Other Hispanic Unknown Mixed Receiving VA disability pension Service connected disability compensation1 50% or more Less than 50% Residential area Urban area Large rural area Small rural area Isolated rural are OEF/OIF era veterans Homeless during the year MEDICAL DIAGNOSIS–GENERAL Metastatic cancer Paraplegia Liver disease Headaches Connective tissue disease Insomnia HIV Seizure disorder Peptic ulcer disease Chronic pulmonary disease Peripheral vascular disease Congestive heart failure Myocardial infarction Charlson Medical Severity Diagnosis Index MEDICAL DIAGNOSIS–PAIN Any pain Herpetic pain Fibromyalgia Musculo skeletal pain (e.g., back pain) Skeleto-spasm pain Pain from diabetes PSYCHIATRIC DIAGNOSIS Major depression Anxiety disorder Other depression (e.g., dysthymia) Bipolar disorder Schizophrenia Dementia Other psychiatric diagnosis SERVICE UTILIZATION Any mental health inpatient treatment Emergency room visits Medical surgical visits

PTSD & SUD (n = 139,731)

Effect Size

Mean 55.194 25763.07 n 454725

SD 15.416 33274.56 % 91.2%

Mean 50.869 21299.78 n 130229

SD 14.187 27697.24 % 93.2%

Cohen’s d −0.28 −0.14 Risk Ratio 1.02

187328 81010 8360 38780 54462 9526 5332

42% 18% 2% 19% 11% 2% 1.1%

90205 32166 1723 10777 11192 3101 5018

70% 25% 1% 15% 8% 2% 3.6%

1.66 1.37 0.71 0.81 0.73 1.12 3.24∗

289718 87393

60.3% 18.2%

66701 25141

47.7% 18.0%

0.79 0.99

334821 59742 48371 37838 115605 15864

69.6% 12.4% 10.1% 7.9% 24.0% 3.3%

100474 15304 11391 8810 35710 26898

73.9% 11.3% 8.4% 6.5% 25.6% 19.2%

1.06 0.90 0.83 0.82 1.06 5.83∗

24 35 13205 58131 5561 41926 1500 4214 4106 74017 21480 259460 6364 Mean 1.508 n 299267 4815 15882 158241 12943 26082

0.005% 0.01% 2.6% 11.7% 1.1% 8.4% 0.3% 0.8% 0.8% 14.8% 4.3% 52.0% 1.3% SD 1.745 % 60.0% 1.0% 3.2% 31.7% 2.6% 5.2%

6 9 10578 16428 1048 14037 1018 1963 1466 23336 5356 73862 1494 Mean 1.398 n 91760 1411 4221 50685 3971 4203

0.0% 0.0% 7.6% 11.8% 0.8% 10.0% 0.7% 1.4% 1.0% 16.7% 3.8% 52.9% 1.1% SD 1.691 % 65.7% 1.0% 3.0% 36.3% 2.8% 3.0%

0.88 0.89 2.86∗ 1.01 0.67 1.20 2.42∗ 1.66 1.27 1.12 0.89 1.02 0.84 Cohen’s d −0.06 Risk Ratio 1.09 1.05 0.95 1.14 1.10 0.58

95439 100319 192574 20195 8515 4147 69829

19.1% 20.1% 38.6% 4.0% 1.7% 0.8% 14.0%

37757 39404 74631 14535 5601 513 32829

27.02% 28.20% 53.41% 10.40% 4.01% 0.37% 23.49%

1.41 1.40 1.38 2.57∗ 2.35∗ 0.44 1.68

7022 Mean 0.50 9.61

0.014 SD 1.36 10.89

19780 Mean 1.17 10.43

0.142 SD 2.56 11.37

10.05∗ Cohen’s d 0.39 0.07

(Continued on next page)

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TABLE 1 (Continued) Bivariate Analysis of Veterans With PTSD, With and Without Substance Use Disorder (N = 638,451) PTSD Alone (n = 498,720) Psychiatric or substance abuse outpatient visits All outpatient visits PSYCHOTROPIC MEDICATION FILLS Any psychotropic Antidepressant Antipsychotic Anticonvulsant or mood stabilizer Sedative hypnotic or analgesic Stimulant Lithium

PTSD & SUD (n = 139,731)

Effect Size

7.53

15.25

23.83

42.07

0.68∗

17.14

20.08

34.27

45.45

0.62∗

12.69 5.93 1.34 1.42 3.20 0.13 0.08

21.23 10.52 7.02 6.27 5.84 1.16 1.57

19.89 9.22 3.49 2.91 3.39 0.15 0.26

35.11 16.39 12.11 10.94 7.33 1.64 3.13

0.29 0.27 0.26 0.20 0.03 0.01 0.09

Note. PTSD = posttraumatic stress disorder; SUD = substance use disorder; OEF/OIF = Operation Enduring Freedom/Operation Iraqi Freedom (i.e., deployed in support of operations in Iraq and/or Afghanistan. ∗ Significant findings are indicated by dichotomous variables with risk ratios greater than 2.0 or less than 0.5, and continuous variables with Cohen’s d greater than 0.5. 1The amount of compensation increases with the severity of the disability, based on a rating of the percentage of disability.

variables with face-value conceptual relevance or substantial risk differences (such as age, race, and seizure disorders, which can be precipitated by substance use), Poisson regression was used to identify independent factors related to dual diagnosis. For continuous variables reflecting age, service use, and prescription fills, estimates and standard errors were multiplied by 10 so that the risk ratio reflect a meaningful but still consistent effect, i.e., the effect of 10 years of age, 10 outpatient visits, or 10 prescriptions. In the case of the Charlson Comorbidity Index, we examined bivariate relations for the overall index as well as for individual component illnesses along with an array of relevant pain diagnoses. A variable representing the date of the first VA outpatient visit of any kind during the fiscal year was used to control for the potential duration of involvement in VA services during the fiscal year. There were only six days of greater potential duration of VA services among those without dual diagnosis (1.6%). Since both dichotomous and continuous variables were included in the analysis, the magnitude of effect was evaluated with a standardized regression coefficient. The study was approved by the institutional review board of the VA Connecticut Healthcare System. A waiver of consent was obtained as the study used administrative data and there were no patient identifiers.

greater likelihood of mental health inpatient treatment, more numerous outpatient mental health visits, as well as all outpatient visits (medical and mental health) combined. While veterans with a dual diagnosis of PTSD and substance use disorder filled more prescriptions for all psychotropic medications with the greatest effect for antidepressants and antipsychotics, the effect sizes were small to moderate in magnitude reflecting the large standard deviations in comparison with the means (Cohen’s d = 0.27 for antidepressants). Poisson regression, controlling for the date of the first visit to VA in the fiscal year (i.e., the period of exposure being from that date to the end of the fiscal year), showed that several variables were independently associated with a dual diagnosis of PTSD and a substance use disorder (Table 2). The largest effects were observed for seizures, with a risk ratio (RR) of 1.92, 95% confidence interval (CI; 1.31–2.82), although base rates were quite low. Large effects were also seen with mental health inpatient treatment, RR = 1.9, 95% CI (1.93–1.99); homelessness, RR = 1.81, 95% CI (1.78–1.83); liver disease, RR = 1.71, 95% CI (1.68–1.73); and VA disability pension, RR = 1.47, 95% CI (1.44–1.51; see Table 2). While modest in magnitude, these were followed in effect size by bipolar disorder, HIV, 10 emergency room visits, major depression, anxiety disorder, and schizophrenia, with more modest risk ratios ranging from 1.27 to 1.07.

RESULTS On bivariate analysis, the factors that most strongly characterized veterans with dual diagnosis of PTSD and substance use disorder were medical diagnoses of HIV and liver disease and psychiatric diagnoses of schizophrenia and bipolar disorder. Veterans with dual diagnosis were also more likely to have been homeless and to receive a VA disability pension (Table 1). In addition, veterans with a dual diagnosis had Journal of Dual Diagnosis

DISCUSSION This national study of VA service users compared veterans with dually diagnosed PTSD and substance use disorder to veterans with PTSD alone and found substantial differences on several sociodemographic and diagnostic characteristics and on measures of service use. Most strikingly, veterans with

PTSD and Substance Use Disorder Among Veterans

TABLE 2 Poisson Regression Analysis of Characteristics of Veterans With PTSD, With and Without Substance Use Disorder

Variable Demographics Age (10 year increments) White race VA disability pension Homeless Medical comorbidity Liver disease HIV Seizure disorder Psychiatric comorbidity Schizophrenia Bipolar disorder Major depression Anxiety disorder Service use All outpatient visits (10 visits) Emergency room visits (10 visits) Mental health outpatient visits (10 visits) Any mental health inpatient treatment Prescriptions Antidepressant medication (10 prescriptions) Antipsychotic medications (10 prescriptions)

Odds Ratio

95% Confidence Interval

0.89 0.86 1.471 1.811

[0.88–0.89] [0.85–0.87] [1.44–1.51] [1.78–1.83]

1.711 1.162 1.921

[1.68–1.73] [1.11–1.22] [1.31–2.82]

1.072 1.272 1.122 1.112

[1.04–1.09] [1.25–1.29] [1.11–1.13] [1.10–1.13]

1.04

[1.04–1.04]

1.142

[1.12–1.16]

1

[1–1]

1.91

[1.99–1.93]]

1.01

[1.01–1.01]

0.99

[0.99–1.00]

Note. 1Large effect size. 2Moderate effect size.

dually diagnosed PTSD and substance use disorder were more likely to have seizure disorder, liver disease, HIV, bipolar disorder, anxiety disorder, and schizophrenia. Veterans with dual diagnosis were also notably more likely to have experienced homelessness and to receive VA disability pensions. Measures of health service use among those with a dual diagnosis showed them to have a significantly greater likelihood of mental health inpatient treatment and to have had greater numbers of emergency department, mental health, and total outpatient visits (mental health plus medical/surgical). There were no substantial differences in the use of psychotropic medications by our preset criteria, although veterans with a dual diagnosis filled somewhat greater numbers of psychotropic prescriptions. Although 21.8% of veterans with PTSD also had substance use disorder, perhaps what is most notable is that those with a dual diagnosis differed substantially from veterans with PTSD alone on only a few, albeit potentially quite important, characteristics. In part, this may be due to our reliance on effect sizes rather than p values to identify substantial differences between the groups. Other studies of veterans with a dual diagnosis in VA relied on p values, which invariably reveal many statistically significant differences in such large samples (Marienfeld & Rosenheck, 2013). These differences are not necessarily of

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clinical importance. In this study, however, all of the measures on which substantial differences emerged using effect size standards showed veterans with dually diagnosed PTSD and substance use disorder to have more severe social, medical, and psychiatric problems as well as higher levels of both inpatient and outpatient service use. These indicators of more severely compromised life circumstances deserve further consideration for their potential implications for treatment. Studies of the general population (Greenberg & Rosenheck, 2010) and veterans in particular (Tsai, Kasprow, & Rosenheck, 2014) confirm that substance abuse is perhaps the most important risk factor for homelessness. A recent reanalysis of national data on the correlates of homelessness showed that persons with substance use disorder were six times more likely to be homeless than others (Greenberg & Rosenheck, 2010).The adjusted odds ratio for substance abuse and homelessness, after taking into account factors such as poverty, race, and mental health diagnosis was reduced to 2.9, which remained higher than the risk of homelessness attributable to non–substance use psychiatric diagnoses. Other studies have shown that 70% of veterans who are homeless experience alcohol and/or substance use problems (Kasprow, Rosenheck, Dilella, Cavallaro, & Harelik, 2009; O’Toole, Gibbon, Hanusa, & Fine, 1999), and a comprehensive review of risk factors associated with homelessness among veterans found a preponderance of evidence that substance abuse was the most important health-related risk factor (Tsai et al., 2014). Our study is thus broadly consistent with previous research on veteran homelessness. In view of this risk, it is important to screen veterans with dually diagnosed PTSD and substance use disorder for difficulties with their housing, to assess their risk of homelessness, and to provide resources to prevent its occurrence. The VA in particular has recently implemented the Support Services for Veterans’ Families program to support veterans and their families who are at risk for homelessness. A recent study found that this program demonstrated a capacity to rapidly re-house and prevent homelessness among vulnerable veteran families through a cost-effective, housing-focused intervention (Department of Veterans Affairs, 2013). For veterans who are currently homeless, a broad array of services are available depending on the specific needs of each homeless veteran (Tsai, Kasprow, & Rosenheck, 2013), but those with substance abuse problems are often best served by an initial stay in a residential treatment program (Kertesz, Crouch, Milby, Cusimano, & Schumacher, 2009). The VA has in fact specifically targeted some interventions for veterans who are homeless and also have PTSD and substance use disorder (Desai, Harpaz-Rotem, Najavits, & Rosenheck, 2008). These interventions have shown improvement in employment, social support, general symptoms of psychiatric distress, and symptoms of PTSD (Desai et al., 2008). A moderately large randomized trial showed reduced substance use among veterans who are homeless in association with entry into supported housing (Cheng, Lin, Kasprow, & Rosenheck, 2015, Volume 11, Number 1

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2007). Other researchers have also demonstrated improvement in psychiatric functioning of substance abusers who are homeless and receive treatment for drug addiction (Kertesz, Madan, Wallace, Schumacher, & Milby, 2006). The importance of housing veterans in order to improve access to care has also been demonstrated (Tsai et al., 2014; Vayalapalli et al., 2013; Winn et al., 2013). Every effort should therefore be made to house veterans with PTSD and substance use disorder who are homeless, as this may also improve health outcomes and access to care. Income has long been recognized as perhaps the most important risk factor for homelessness, as most people who are homeless are from the lowest segment of the poor (Rossi 1989). It is thus not surprising that within the VA, receiving serviceconnected disability income has been found to be associated with a reduction in the risk of homelessness (Edens, Kasprow, Tsai, & Rosenheck, 2011). This study found only modest differences in service-connected status and income between veterans with both PTSD and substance use disorder compared to veterans with PTSD alone, and it is likely that substance abuse is the more important risk factor for homelessness in this population. Although no substantial differences were found in income and receipt of service-connected disability benefits between the two groups, there was a substantial difference with the receipt of VA disability pension benefits. Previous studies have shown that veterans who are homeless are far more likely to receive VA disability pensions than service-connected disability benefits (Chen, Rosenheck, Greenberg, & Seibyl, 2007). Our study found that veterans with dually diagnosed PTSD and substance use disorder were 1.47 times more likely to have received a pension, perhaps reflecting a greater number of veterans that are homeless in this group. However, since only 1.1% of veterans with PTSD alone and 3.6% of veterans with dual diagnosis actually receive pensions, it may be that some veterans with PTSD may still be eligible for pension support. We further note that becoming homeless itself is a traumatic experience and may be associated with exposure to further traumatic experiences that may themselves result in PTSD symptoms and self-medication with addictive substances, thereby adding to the comorbidity of PTSD and substance use disorders in this population. However, no studies that we are aware of have examined this issue, in part because it would be very difficult to collect baseline data at the time a veteran first became homeless and follow-up data thereafter. In view of the fact that veterans with dually diagnosed PTSD and substance use disorder had slightly lower Charlson Comorbidity Index medical severity scores, it is notable that they stood out as having a higher prevalence of several specific disorders including seizures, HIV, and liver disease. As reported above, 53.9% of veterans with a dual diagnosis had a drug abuse disorder, and some may have used intravenous drugs, which would put them at a higher risk for HIV and hepatitis C. Similarly, 75% of veterans with a dual diagnosis had Journal of Dual Diagnosis

an alcohol use disorder, which places them at risk for alcoholrelated liver disease, and both alcohol and drug use increase the risk of seizures. The high rates of liver disease are likely related to both hepatitis C infections as well as alcoholic liver disease. Clinicians who are treating PTSD and substance use disorder in veterans should therefore be alerted to these high prevalence rates and routinely target these veterans for dual diagnosis screening and, if appropriate, for treatment. Veterans with dual diagnosis who have not had screenings for these disorders should have appropriate assessments to enhance early detection and implementation of effective treatment. These assessments should occur throughout the course of care, especially if substance use is ongoing. While veterans with diagnosed PTSD and substance use disorder in our study have a somewhat higher risk of psychiatric comorbidity on all psychiatric diagnoses except for dementia, it is notable that on both bivariate and multivariable Poisson regression analyses, the greatest independent risk was bipolar disorder and schizophrenia. On Poisson regression only, anxiety disorder and major depression were of statistical significance. This has also been previously observed in in earlier VA data (Petrakis et al., 2011). Substance misuse is particularly common among people with bipolar disorder (Merikangas et al., 2008), and its co-occurrence has been reported to lead to a more pernicious and difficult to treat illness (Post & Kalivas, 2013). Veterans with bipolar disorder in addition to PTSD and substance use disorder perhaps deserve special attention, as both bipolar and substance use disorders have difficult treatment courses and are associated with an elevated risk of suicide (Ilgen et al., 2010). Data from the National Comorbidity Study suggest that substance use disorders are associated with increased odds of comorbid mood disorders and bipolar disorder in particular (Kenneson, Funderburk, & Maisto, 2013). Accordingly, veterans with dually diagnosed PTSD and substance use disorder in addition to mood disorders should be especially encouraged to engage in sustained mental health services. These services should include routine assessment for mood disorders and, in particular, bipolar disorder and suicidality. Veterans with diagnosed PTSD, substance use disorder, and bipolar disease should be offered the appropriate effective interventions. In this study we found that veterans with PTSD and substance use disorder had a slightly higher risk of having schizophrenia. Reliving symptoms of PTSD, however, can be confused with hallucinations of schizophrenia so the diagnoses can be confused (Hamner, Frueh, Ulmer, & Arana, 1999). Veterans with comorbid schizophrenia and PTSD have been found to have a decreased quality of life and increased medical service utilization, including increased psychiatric hospitalization and increased outpatient physical health visits (Calhoun, Bosworth, Stechuchak, Strauss, & Butterfield, 2006). This finding was confirmed by researchers who investigated service utilization in veterans with schizophrenia and anxiety disorders (Birgenheir, Ganoczy, & Bowersox,

PTSD and Substance Use Disorder Among Veterans

2014). Given the great disease burden of this illness, veterans with dual diagnosis should be screened for schizophrenia and treated accordingly. Future research should investigate ways to improve detection and enhance treatment provided to this population. Despite showing that veterans with a dual diagnosis of both PTSD and substance use disorder have higher rates of bipolar disorder and schizophrenia, our study also showed that they are not especially more likely to receive lithium, antipsychotics, or mood stabilizers, the primary treatments for these disorders, which may reflect suboptimal treatment. Further research is needed to determine whether these veterans with PTSD, substance use disorder, and comorbid bipolar disorder or schizophrenia are undertreated, noncompliant with treatment recommendations and not filling prescriptions, or perhaps filling prescriptions outside of VA pharmacies. Previous VA studies of patients with a psychiatric illness with substance use disorder (Hoff & Rosenheck, 1998) and those with substance abuse with comorbid psychiatric disorders (Hoff & Rosenheck, 1999) as well as of non-VA patients with a dual diagnosis (Bartels et al., 1993; Dixon, McNary, & Lehman, 1997) have demonstrated higher levels of service use and cost among patients with a dual diagnosis. Some substance abuse treatment facilities do not treat patients with a comorbid psychiatric diagnosis (Drake, McHugo, & Noordsy, 1993), and others report that patients with a dual diagnosis leave treatment earlier than others (Leon, Lyons, Christopher, & Miller, 1998). Similar to the current study, these reports demonstrate that service utilization of veterans with PTSD and substance use disorders remains considerably higher than among those with PTSD alone, especially in the case of emergency department use. As far as we know, there has been no prior study of a national sample of veterans with PTSD and substance use disorder that examined service utilization. Our study shows that veterans with PTSD and substance use disorder have higher rates of psychiatric hospitalization than those with PTSD alone. On bivariate analysis they appear to also utilize psychiatric and substance abuse outpatient services as well as all outpatient services; however, in the Poisson regression this finding was not confirmed. Emergency department visits were statistically significant on Poisson regression; however, on bivariate analysis emergency department visits did not show a significant effect size. This high use of psychiatric inpatient services may reflect higher chronic disease burden, and it therefore becomes important to facilitate access inpatient psychiatric care for these veterans. A single-site study of veterans in Charleston, South Carolina, demonstrated that evidence-based treatment for PTSD was associated with large reductions in symptoms and that diagnostic remission was associated with substantial reductions in mental health service utilization and health care costs, particularly for veterans who completed treatment (Tuerk et al., 2013). Similarly, researchers at the Minneapolis VA noted a decrease in individual and group therapy after veterans had re-

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ceived treatment for PTSD, amounting to a 39.4% decrease in cost associated with mental health care (Meyers et al., 2013). Veterans with dually diagnosed PTSD and substance use disorder should thus be connected with services that utilize evidence-based PTSD treatment protocols. Psychoeducational interventions could emphasize to veterans that better outcomes are associated with completion of treatment. The integrated model for treating serious mental illness in clients with a dual diagnosis through assertive community treatment teams staffed with both substance abuse and mental health specialists has been shown to be more effective than such teams without the substance abuse specialist in several studies (Drake et al., 2001). A similar integrated service model specific to PTSD, although not based on the assertive community treatment model, has been implemented in the VA by increasing the presence of substance use treatment specialists in specialized PTSD treatment programs. Educational efforts have been made to foster coordination of treatment planning and delivery of services (Bernardy, Hamblen, Friedman, & Kivlahan, 2011). Specialists are trained in evidencebased psychotherapeutic treatments for PTSD, in addition to pharmacotherapy. Individual treatments are offered to patients with dual diagnosis (Boden et al., 2012; Currier, Holland, & Drescher, 2014; Foa et al., 2013). As noted above, a previous study of veterans with diagnosed schizophrenia or bipolar disorder in addition to PTSD and substance use disorder found that they received a larger number of psychotropic medications (Marienfeld & Rosenheck 2013). Our findings showed a greater number of prescription fills among veterans with dual diagnosis (Table 2). However, when the effect size standards used here were applied to these data, differences were not substantial due to high variability in the number of prescriptions. This small, albeit positive, effect size was also apparent in the multivariate Poisson model.

Limitations A major strength of this study is that it is based on a large comprehensive national VA sample. However, only veterans who utilize VA services are included in this study and those veterans who seek care in non-VA facilities are not represented. Thus, its applicability to veterans who utilize services outside of the VA and to non-veteran patients with dually diagnosed PTSD is unknown. Second, diagnoses in administrative databases are not made with standardized research instruments and their formal validity is thus uncertain. Although high-risk alcohol screening has been implemented since 2004 for post–Afghanistanand Iraq-deployed veterans (Seal et al., 2008), it has been suggested that substance use disorders remain underdiagnosed in administrative data (Institute of Medicine, 2013; Seal et al., 2011). As a result, we may have underestimated the differences observed between veterans with a dual diagnosis compared to PTSD alone. In addition, since 2003 the 2015, Volume 11, Number 1

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Department of Defense implemented a military-wide screening program, the Post-Deployment Health Assessment, which included screening for PTSD (Gates et al., 2012; Hoge, Auchterlonie, & Milliken, 2006). This program has been revised over the years and includes an ongoing assessment for PTSD (Milliken, Auchterlonie, & Hoge, 2007). There has also been increasing emphasis within VA on identifying veterans with PTSD and substance use disorder (Bernardy et al., 2011), with clear evidence that the PTSD diagnosis is being used with increasing frequency (Hermes, Hoff, & Rosenheck, 2014). PTSD may therefore be diagnosed with greater regularity than substance use disorders in the VA in recent years and, in comparison, result in an underdiagnosis of dual diagnosis in veterans. A third limitation of this study is the selection of medical diagnosis. It was not possible to evaluate all medical diagnoses, so we focused on those represented in the Charlson Comorbidity Index along with selected pain diagnoses. A fourth limitation of this study is in the interpretation of our data. Risk ratios are highly dependent on base prevalence rates (Ferguson, 2009). As noted by Ferguson, a risk ratio of 2 may not be as important if the base rate of a disease is 1% as compared to a base rate of 10%. Similarly, the risk difference is naturally constrained (like the risk ratio), which may create difficulties when applying results to other patient groups and settings. We have examined risk differences for variables with high base rates but low risk ratios. Finally, throughout this discussion, various specialized treatment options have been suggested to meet the distinctive needs of veterans with dual diagnosis. However, no data are available to determine past and current access to or use of these treatment options and thus we cannot come to any firm conclusions about undertreatment. Conclusion In this national VA study a number of substantial differences were observed, each of which represented more severe medical and psychiatric illness among veterans with PTSD and substance use disorder as opposed to PTSD alone. Specialized treatments are available for these problems, and efforts should be made to ensure that they are accessible and are being used where indicated. DISCLOSURES Drs. Bowe and Rosenheck report no financial relationships with commercial interests with regard to this manuscript.

FUNDING Funding for this study came from the VA New England MIRECC. Journal of Dual Diagnosis

REFERENCES Abrams, T. E., Lund, B. C., Bernardy, N. C., & Friedman, M. J. (2013). Aligning clinical practice to PTSD treatment guidelines: Medication prescribing by provider type. Psychiatric Services, 64(2), 142–148. doi:10.1176/appi.ps.201200217 Bartels, S. J., Teague, G. B., Drake, R. E., Clark, R. E., Bush, P. W., & Noordsy, D. L. (1993). Substance abuse in schizophrenia: Service utilization and costs. The Journal of Nervous and Mental Disease, 181(4), 227–232. Bauer, M. S., Lee, A., Li, M., Bajor, L., Rasmusson, A., & Kazis, L. E. (2014). Off-label use of second generation antipsychotics for post-traumatic stress disorder in the Department of Veterans Affairs: Time trends and sociodemographic, comorbidity, and regional correlates. Pharmacoepidemiology and Drug Safety, 23(1), 77–86. doi:10.1002/pds.3507 Bernardy, N. C., Hamblen, J. L., Friedman, M. J., & Kivlahan, D. R. (2011). Co-occurring posttraumatic stress disorder and substance use disorder: Recommendations for management and implementation in the Department of Veterans Affairs. Journal of Dual Diagnosis, 7(4), 242–261. doi:10.1080/15504263.2011.620446 Bernardy, N. C., Lund, B. C., Alexander, B., Jenkyn, A. B., Schnurr, P. P., & Friedman, M. J. (2013). Gender differences in prescribing among veterans diagnosed with posttraumatic stress disorder. Journal of General Internal Medicine, 28 (Suppl 2), S542–S548. doi:10.1007/s11606-012-2260-9 Birgenheir, D. G., Ganoczy, D., & Bowersox, N. W. (2014). Service utilization among veterans with schizophrenia and a comorbid anxiety disorder. Psychiatric Services. Advance online publication. doi:10.1176/appi.ps.201300316 Boden, M. T., Kimerling, R., Jacobs-Lentz, J., Bowman, D., Weaver, C., Carney, D., . . . Trafton, J. A. (2012). Seeking safety treatment for male veterans with a substance use disorder and post-traumatic stress disorder symptomatology. Addiction, 107(3), 578–586. doi:10.1111/j.13600443.2011.03658.x Calhoun, P. S., Bosworth, H. B., Stechuchak, K. A., Strauss, J., & Butterfield, M. I. (2006). The impact of posttraumatic stress disorder on quality of life and health service utilization among veterans who have schizophrenia. Journal of Traumatic Stress, 19(3), 393–397. doi:10.1002/jts.20114 Charlson, M. E., Pompei, P., Ales, K. L., & MacKenzie, C. R. (1987). A new method of classifying prognostic comorbidity in longitudinal studies: Development and validation. Journal of Chronic Diseases, 40(5), 373–383. Chen, J. H., Rosenheck, R. A., Greenberg, G. A., & Seibyl, C. (2007). Factors associated with receipt of pension and compensation benefits for homeless veterans in the VBA/VHA Homeless Outreach Initiative. Psychiatric Quarterly, 78(1), 63–72. doi:10.1007/s11126-006-9027-6 Cheng, A.-L., Lin, H., Kasprow, W., & Rosenheck, R. A. (2007). Impact of supported housing on clinical outcomes: Analysis of a randomized trial using Multiple Imputation Technique. Journal of Nervous and Mental Disease, 195(1), 83–88. Cohen, B. E., Gima, K., Bertenthal, D., Kim, S., Marmar, C. R., & Seal, K. H. (2010). Mental health diagnoses and utilization of VA non-mental health medical services among returning Iraq and Afghanistan veterans. Journal of General Internal Medicine, 25(1), 18–24. doi:10.1007/s11606009-1117-3 Cohen, J. (1998). Statistical power analysis for the behavioral sciences. Hillsdale, NJ: L. Erlbaum Associates. Currier, J. M., Holland, J. M., & Drescher, K. D. (2014). Residential treatment for combat-related posttraumatic stress disorder: Identifying trajectories of change and predictors of treatment response. Public Library of Science One, 9(7), e101741. doi:10.1371/journal.pone.0101741 Department of Veterans Affairs. (2013). Effectiveness of permanent housing FY-2012 report. Retrieved from http://www.va.gov/HOMELESS/ docs/SSVF/Effectiveness of SSVF Program Report FY2012.pdf Desai, R. A., Harpaz-Rotem, I., Najavits, L. M., & Rosenheck, R. A. (2008). Impact of the Seeking Safety program on clinical outcomes among

PTSD and Substance Use Disorder Among Veterans

homeless female veterans with psychiatric disorders. Psychiatric Services, 59(9), 996–1003. doi:10.1176/appi.ps.59.9.996 Dixon, L., McNary, S., & Lehman, A. (1997). One-year follow-up of secondary versus primary mental disorder in persons with comorbid substance use disorders. The American Journal of Psychiatry, 154(11), 1610–1612. Drake, R. E., Essock, S. M., Shaner, A., Carey, K. B., Minkoff, K., Kola, L., . . . Rickards, L. (2001). Implementing dual diagnosis services for clients with severe mental illness. Psychiatric Services, 52(4), 469–476. Drake, R. E., McHugo, G. J., & Noordsy, D. L. (1993). Treatment of alcoholism among schizophrenic outpatients: 4-year outcomes. The American Journal of Psychiatry, 150(2), 328–329. Edens, E. L., Kasprow, W., Tsai, J., & Rosenheck, R. A. (2011). Association of substance use and VA service-connected disability benefits with risk of homelessness among veterans. The American Journal on Addictions, 20(5), 412–419. doi:10.1111/j.1521-0391.2011.00166.x Ferguson, C. J. (2009). An effect size primer: A guide for clinicians and researchers. Professional Psychology: Research and Practice, 40(5), 532– 538. doi:10.1037/a0015808 Foa, E. B., Yusko, D. A., McLean, C. P., Suvak, M. K., Bux, D. A., Jr., Oslin, D., . . . Volpicelli, J. (2013). Concurrent naltrexone and prolonged exposure therapy for patients with comorbid alcohol dependence and PTSD: A randomized clinical trial. JAMA: The Journal of the American Medical Association, 310(5), 488–495. doi:10.1001/jama.2013.8268 Gates, M. A., Holowka, D. W., Vasterling, J. J., Keane, T. M., Marx, B. P., & Rosen, R. C. (2012). Posttraumatic stress disorder in veterans and military personnel: Epidemiology, screening, and case recognition. Psychological Services, 9(4), 361–382. doi:10.1037/a0027649 Greenberg, G. A., & Rosenheck, R. A. (2010). Correlates of past homelessness in the National Epidemiological Survey on Alcohol and Related Conditions. Administration and Policy in Mental Health and Mental Health Services Research, 37(4), 357–366. doi:10.1007/s10488009-0243-x Hamner, M. B., Frueh, B. C., Ulmer, H. G., & Arana, G. W. (1999). Psychotic features and illness severity in combat veterans with chronic posttraumatic stress disorder. Biological Psychiatry, 45(7), 846–852. Hawkins, E. J., Malte, C. A., Imel, Z. E., Saxon, A. J., & Kivlahan, D. R. (2012). Prevalence and trends of benzodiazepine use among Veterans Affairs patients with posttraumatic stress disorder, 2003–2010. Drug and Alcohol Dependence, 124(1–2), 154–161. doi:10.1016/j.drugalcdep.2012.01.003 Hermes, E. D., Hoff, R., & Rosenheck, R. A. (2014). Sources of the increasing number of Vietnam era veterans with a diagnosis of PTSD using VHA services. Psychiatric Services, 65(6), 830–832. doi:10.1176/appi.ps.201300232 Hermes, E. D., Rosenheck, R. A., Desai, R., & Fontana, A. F. (2012). Recent trends in the treatment of posttraumatic stress disorder and other mental disorders in the VHA. Psychiatric Services, 63(5), 471–476. doi:10.1176/appi.ps.201100432 Hoff, R. A., & Rosenheck, R. A. (1998). Long-term patterns of service use and cost among patients with both psychiatric and substance abuse disorders. Medical Care, 36(6), 835–843. Hoff, R. A., & Rosenheck, R. A. (1999). The cost of treating substance abuse patients with and without comorbid psychiatric disorders. Psychiatric Services, 50(10), 1309–1315. Hoge, C. W., Auchterlonie, J. L., & Milliken, C. S. (2006). Mental health problems, use of mental health services, and attrition from military service after returning from deployment to Iraq or Afghanistan. JAMA: The Journal of the American Medical Association, 295(9), 1023–1032. doi:10.1001/jama.295.9.1023 Ilgen, M. A., Bohnert, A. S., Ignacio, R. V., McCarthy, J. F., Valenstein, M. M., Kim, H. M., & Blow, F. C. (2010). Psychiatric diagnoses and risk of suicide in veterans. Archives of General Psychiatry, 67(11), 1152–1158. doi:10.1001/archgenpsychiatry.2010.129 Institute of Medicine (IOM). (2013). Substance use disorders in the U.S. Armed Forces. Washington, DC: National Academies Press.

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Kasprow, W. J., Rosenheck, R. A., Dilella, D., Cavallaro, L., & Harelik, N. (2009). Health care for homeless veterans programs: Twentysecond progress report. West Haven, CT: Northeast Program Evaluation Center. Kenneson, A., Funderburk, J. S., & Maisto, S. A. (2013). Substance use disorders increase the odds of subsequent mood disorders. Drug and Alcohol Dependence, 133(2), 338–343. doi:10.1016/j.drugalcdep.2013.06.011 Kertesz, S. G., Crouch, K., Milby, J. B., Cusimano, R. E., & Schumacher, J. E. (2009). Housing first for homeless persons with active addiction: Are we overreaching? The Milbank Quarterly, 87(2), 495–534. doi:10.1111/j.1468-0009.2009.00565.x Kertesz, S. G., Madan, A., Wallace, D., Schumacher, J. E., & Milby, J. B. (2006). Substance abuse treatment and psychiatric comorbidity: Do benefits spill over? Analysis of data from a prospective trial among cocainedependent homeless persons. Substance Abuse Treatment, Prevention,and Policy, 1, 27. doi:10.1186/1747-597x-1-27 Kessler, R. C., Sonnega, A., Bromet, E., Hughes, M., & Nelson, C. B. (1995). Posttraumatic stress disorder in the National Comorbidity Survey. Archives of General Psychiatry, 52(12), 1048–1060. Kramer, T. L., Booth, B. M., Han, X., & Williams, D. K. (2003). Service utilization and outcomes in medically ill veterans with posttraumatic stress and depressive disorders. Journal of Traumatic Stress, 16(3), 211–219. doi:10.1023/a:1023783705062 Kulka, R. A., Schlenger, W. E., Fairbank, J. A., Hough, R. L., Jordan, B. K., Marmar, C. R., & Weiss, D. S. (1990). The National Vietnam Veterans Readjustment Study: Tables of findings and technical appendices. New York, NY: Brunner/Mazel. Leon, S. C., Lyons, J. S., Christopher, N. J., & Miller, S. I. (1998). Psychiatric hospital outcomes of dual diagnosis patients under managed care. The American Journal on Addictions, 7(1), 81–86. Lockwood, A., Steinke, D. T., & Botts, S. R. (2009). Medication adherence and its effect on relapse among patients discharged from a Veterans Affairs posttraumatic stress disorder treatment program. The Annals of Pharmacotherapy, 43(7), 1227–1232. doi:10.1345/aph.1M017 Lund, B. C., Abrams, T. E., Bernardy, N. C., Alexander, B., & Friedman, M. J. (2013). Benzodiazepine prescribing variation and clinical uncertainty in treating posttraumatic stress disorder. Psychiatric Services, 64(1), 21–27. doi:10.1176/appi.ps.201100544 Marienfeld C., & Rosenheck R. A. (2013). National psychotropic prescription dispensation among dually diagnosed patients. Advances in Dual Diagnosis, 6, 34–44. Merikangas, K. R., Herrell, R., Swendsen, J., Rossler, W., Ajdacic-Gross, V., & Angst, J. (2008). Specificity of bipolar spectrum conditions in the comorbidity of mood and substance use disorders: Results from the Zurich cohort study. Archives of General Psychiatry, 65(1), 47–52. doi:10.1001/archgenpsychiatry.2007.18 Meyers, L. L., Strom, T. Q., Leskela, J., Thuras, P., Kehle-Forbes, S. M., & Curry, K. T. (2013). Service utilization following participation in cognitive processing therapy or prolonged exposure therapy for post-traumatic stress disorder. Military Medicine, 178(1), 95–99. Milliken, C. S., Auchterlonie, J. L., & Hoge, C. W. (2007). Longitudinal assessment of mental health problems among active and reserve component soldiers returning from the Iraq war. JAMA: The Journal of the American Medical Association, 298(18), 2141–2148. doi:10.1001/jama.298. 18.2141 Morasco, B. J., & Dobscha, S. K. (2008). Prescription medication misuse and substance use disorder in VA primary care patients with chronic pain. General Hospital Psychiatry, 30(2), 93–99. doi:10.1016/j.genhosppsych.2007.12.004 Morrill, R., Cromartie, J., & Hart, L. (1999). Metropolitan urban and rural commuting areas: Toward a better depiction of the U.S. settlement system. Urban Geography, 20(8), 727–748. Nazarian, D., Kimerling, R., & Frayne, S. M. (2012). Posttraumatic stress disorder, substance use disorders, and medical comorbidity among returning U.S. veterans. Journal of Traumatic Stress, 25(2), 220–225. doi:10.1002/jts.21690

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Needham, D. M., Scales, D. C., Laupacis, A., & Pronovost, P. J. (2005). A systematic review of the Charlson comorbidity index using Canadian administrative databases: A perspective on risk adjustment in critical care research. Journal of Critical Care, 20(1), 12–19. Norman, S. B., Tate, S. R., Anderson, K. G., & Brown, S. A. (2007). Do trauma history and PTSD influence addiction relapse context? Drug and Alcohol Dependence, 90, 89–96. O’Toole, T. P., Gibbon, J. L., Hanusa, B. H., & Fine, M. J. (1999). Utilization of health care services among subgroups of urban homeless and housed poor. Journal of Health Politics, Policy and Law, 24(1), 91–114. Ouimette, P. C., Brown, P. J., & Najavits, L. M. (1998). Course and treatment of patients with both substance use and posttraumatic stress disorders. Addictive Behaviors, 23(6), 785–795. Petrakis, I. L., Rosenheck, R., & Desai, R. (2011). Substance use comorbidity among veterans with posttraumatic stress disorder and other psychiatric illness. The American Journal on Addictions, 20(3), 185–189. doi:10.1111/j.1521-0391.2011.00126.x Post, R. M., & Kalivas, P. (2013). Bipolar disorder and substance misuse: Pathological and therapeutic implications of their comorbidity and cross-sensitisation. The British Journal of Psychiatry, 202(3), 172–176. doi:10.1192/bjp.bp.112.116855 Pukay-Martin, N. D., Pontoski, K. E., Maxwell, M. A., Calhoun, P. S., Dutton, C. E., Clancy, C. P., . . . Beckham, J. C. (2012). The influence of depressive symptoms on suicidal ideation among U.S. Vietnam-era and Afghanistan/Iraq-era veterans with posttraumatic stress disorder. Journal of Traumatic Stress, 25(5), 578–582. doi:10.1002/jts.21741 Quan, H., Li, B., Couris, C. M., Fushimi, K., Graham, P., Hider, P., Januel, J. M., & Sundararajan, V. (2011). Updating and validating the Charlson comorbidity index and score for risk adjustment in hospital discharge abstracts using data from 6 countries. American Journal of Epidemiology, 173, 676–682. Rossi, P. H. (1991). Down and out in America: The origins of homelessness. Chicago, IL: University of Chicago Press. Seal, K. H., Bertenthal, D., Maguen, S., Gima, K., Chu, A., & Marmar, C. R. (2008). Getting beyond “Don’t ask; don’t tell”: An evaluation of US Veterans Administration postdeployment mental health screening of veterans returning from Iraq and Afghanistan. American Journal of Public Health, 98(4), 714–720. doi:10.2105/ajph.2007.115519

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Seal, K. H., Cohen, G., Waldrop, A., Cohen, B. E., Maguen, S., & Ren, L. (2011). Substance use disorders in Iraq and Afghanistan veterans in VA healthcare, 2001–2010: Implications for screening, diagnosis and treatment. Drug and Alcohol Dependence, 116(1–3), 93–101. doi:10.1016/j.drugalcdep.2010.11.027 Sernyak, M. J., Kosten, T. R., Fontana, A., & Rosenheck, R. (2001). Neuroleptic use in the treatment of post-traumatic stress disorder. Psychiatric Quarterly, 72(3), 197–213. Tate, S. R., Norman, S. B., McQuaid, J. R., & Brown, S. A. (2007). Health problems of substance-dependent veterans with and those without trauma history. Journal of Substance Abuse Treatment, 33(1), 25–32. doi:10.1016/j.jsat.2006.11.006 Tsai, J., Kasprow, W. J., & Rosenheck, R. A. (2013). Latent homeless risk profiles of a national sample of homeless veterans and their relation to program referral and admission patterns. American Journal of Public Health, 103 Suppl 2, S239–S247. doi:10.2105/ajph.2013.301322 Tsai, J., Kasprow, W. J., & Rosenheck, R. A. (2014). Alcohol and drug use disorders among homeless veterans: Prevalence and association with supported housing outcomes. Addictive Behaviors, 39(2), 455–460. doi:10.1016/j.addbeh.2013.02.002 Tuerk, P. W., Wangelin, B., Rauch, S. A., Dismuke, C. E., Yoder, M., Myrick, H., . . . Acierno, R. (2013). Health service utilization before and after evidence-based treatment for PTSD. Psychological Services, 10(4), 401– 409. doi:10.1037/a0030549 Vayalapalli, S., Fareed, A., Byrd-Sellers, J., Stout, S., Casarella, J., & Drexler, K. (2013). Predictors of substance abuse treatment outcome in hospitalized veterans. The American Journal on Addictions, 22(4), 358–365. doi:10.1111/j.1521-0391.2013.12050.x Whitehead, A. J., Dobscha, S. K., Morasco, B. J., Ruimy, S., Bussell, C., & Hauser, P. (2008). Pain, substance use disorders and opioid analgesic prescription patterns in veterans with hepatitis C. Journal of Pain and Symptom Management, 36(1), 39–45. doi:10.1016/j.jpainsymman.2007. 08.013 Winn, J. L., Shealy, S. E., Kropp, G. J., Felkins-Dohm, D., GonzalesNolas, C., & Francis, E. (2013). Housing assistance and case management: Improving access to substance use disorder treatment for homeless veterans. Psychological Services, 10(2), 233–240. doi:10.1037/ a0031051

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