Prevalence, Correlates, and Burden of Subthreshold PTSD in US Veterans
Symptoms of posttraumatic stress disorder (PTSD) are common following trauma exposure, but most individuals do not meet all criteria to qualify for the diagnosis.1,2 For those who do, the detrimental effects of PTSD are well documented, with these individuals more likely to experience other psychiatric disorders, worse functioning, and suicidal thoughts and behaviors,3,4 as well as increased risk of physical health morbidities and early mortality.5,6 Although several studies have examined the prevalence, correlates, and overall burden of subthreshold PTSD (ie, endorsing some clinically significant PTSD symptoms but not enough to meet full diagnostic criteria4,7–10), definitions of subthreshold PTSD have varied considerably and often relied exclusively on symptom criteria (ie, number of PTSD symptoms or symptom clusters endorsed) and/or outdated diagnostic criteria (eg, DSM-IV), which can affect the accuracy and utility of prevalence estimates.
To date, contemporary, population-based data on the epidemiology of subthreshold PTSD are limited, and no known study has examined the prevalence and correlates of subthreshold PTSD using DSM-5 PTSD symptom criteria, symptom duration, and distress/ impairment in a nationally representative sample of US veterans. Given that subthreshold PTSD is associated with a more than 6-fold greater likelihood of developing PTSD relative to individuals with no/ minimal PTSD symptoms,11 epidemiologic studies of subthreshold PTSD, particularly in higher-risk populations, such as US military veterans, are needed. Such efforts may help identify factors associated with subthreshold PTSD, which can inform prevention, risk stratification, and treatment efforts.
To address this gap, we analyzed data from a large, contemporary, nationally representative sample of US veterans to (1) provide an up-to-date estimate of the prevalence of subthreshold and full PTSD; (2) identify sociodemographic, military, and trauma exposure variables associated with subthreshold PTSD and PTSD; and (3) examine the psychiatric and functional burden of subthreshold and full PTSD.
METHODS
Sample
Data were analyzed from the National Health and Resilience in Veterans Study (NHRVS), which surveyed a nationally representative sample of 4,069 US veterans. Full details about the methodology can be found elsewhere.12 Briefly, participants completed an anonymous, web-based survey. The sample was drawn from KnowledgePanel, a survey panel of more than 50,000 US households maintained by Ipsos, a research firm. KnowledgePanel is a probability-based survey panel of a representative sample of US adults that covers approximately 98% of US households. Panel members are recruited through national random samples, originally by telephone and now almost entirely by postal mail. To permit generalizability of results to the US veteran population, poststratification weights using benchmark distributions of US military veterans from the most contemporaneous (August 2019) Veterans Supplement of the Current Population Survey13 were applied in all inferential analyses. All procedures were approved by the Human Subjects Committee of the VA Connecticut Healthcare System, and all participants provided electronic informed consent.
Measures
Probable full PTSD. Lifetime PTSD symptoms were assessed using a modified version of the PTSD Checklist for DSM-5.14 After completing the Life Events Checklist for DSM-5 (LEC-5),15 which assesses lifetime exposure to 16 potentially traumatic events (PTEs) and an open-ended “other” event, participants who endorsed 1 or more PTEs were shown their endorsed PTEs and prompted to select “your worst stressful experience” and indicate “how much you have been bothered by that problem ever in your lifetime (eg, repeated, disturbing, and unwanted memories of the stressful experience).” Full PTSD was operationalized as endorsement of a PTE on the LEC-5 (Criterion A); each of the 4 DSM-5 PTSD symptoms clusters (Criteria B–E; ie, endorsement of “moderate” or greater severity of 1 or more intrusion symptoms; 1 or more avoidance symptoms; 2 or more negative alterations in cognitions and mood symptoms; and 2 or more alterations in arousal and reactivity symptoms); symptom duration of more than 1 month (Criterion F; “How long did these reactions last?”); and PTSD symptom-related distress or functional impairment (Criterion G; endorsement of “moderately,” “quite a bit,” or “extremely” in response to the question: “Did these reactions cause you distress or result in a failure to fulfill obligations at home, work, or school?”).
Probable subthreshold PTSD. Consistent with a recently proposed working case definition of subthreshold PTSD,16 subthreshold PTSD was operationalized as endorsement of a PTE on the LEC-5 (Criterion A); any 2 or 3 PTSD symptom clusters (Criteria B–E); symptom duration of more than 1 month (Criterion F); and PTSD symptom-related distress or functional impairment (Criterion G). Veterans who did not meet case definitions for full or subthreshold PTSD were classified as no PTSD.
A broad range of sociodemographic (eg, age and race/ ethnicity), military (eg, combat veteran status), trauma (eg, adverse childhood experiences [ACEs]), psychiatric (eg, lifetime history of major depressive disorder [MDD]), and functioning (eg, psychosocial difficulties) measures were examined as potential correlates of lifetime PTSD screening status. Table 1 provides a description of these measures.
Data Analysis
Data analyses proceeded in 4 steps. First, descriptive statistics were computed to estimate the prevalence of PTSD screening status (ie, no PTSD, subthreshold PTSD, and full PTSD). Second, 1-way analyses of variance (ANOVAs) and χ2 analyses were conducted to compare sociodemographic, military, trauma exposure, and psychiatric characteristics by PTSD screening status. Third, a series of binary multivariable logistic regression analyses were conducted to examine associations between PTSD screening status and positive screens for current and lifetime psychiatric and substance use disorders (eg, current MDD; current generalized anxiety disorder [GAD]; lifetime alcohol use disorder [AUD]; and lifetime drug use disorder [DUD]), as well as endorsement of suicidal thoughts and behaviors (ie, current suicidal ideation [SI] and lifetime suicide attempt) and mental health treatment history. Fourth, a series of weighted multivariable analyses of covariance were conducted to examine associations between PTSD screening status and scores on measures of mental, psychosocial, and cognitive functioning; variables that differed by group in bivariate analyses (P<.01) were adjusted for in multivariable analyses.
RESULTS
Prevalence of Probable Full and Subthreshold PTSD
Among the 4,069 veterans included in the total sample, 295 (weighted 8.4%, 95% CI, 7.2%–9.7%) screened positive for lifetime full PTSD and 159 (weighted 3.9%, 95% CI, 3.2%–4.8%) for lifetime subthreshold PTSD. In the subthreshold PTSD group, the median number of PTSD symptom clusters endorsed (ie, Criteria B–E) was 3. The remainder of the sample (N=3,615; weighted 87.7%, 95% CI, 86.2%–89.1%) did not meet criteria for either subthreshold or full lifetime PTSD. The mean PCL-5 score in the full PTSD and subthreshold PTSD groups was 47.9 (SD=13.4) and 26.8 (SD=9.0), respectively.
Sociodemographic and Military Correlates of Full and Subthreshold PTSD
Table 2 shows the results of ANOVA and χ2 analyses of sociodemographic, military, and treatment characteristics by PTSD screening status. Veterans with full PTSD were the youngest, followed by the subthreshold and no PTSD groups. Relative to veterans with no PTSD, those with full or subthreshold PTSD were more likely to be female, less likely to be married or living with a partner, and less likely to report an annual household income greater than $60,000. Veterans with full PTSD were most likely to report using the Veterans Affairs (VA) as their primary source of healthcare and to have ever and currently be engaged in mental health treatment. Veterans with subthreshold PTSD were more likely than veterans with no PTSD to use the VA and to have ever and currently be engaged in mental health treatment. Relative to veterans with no PTSD, those with full PTSD were more likely to be Hispanic and combat veterans.
Trauma Exposure and Psychiatric Correlates of Full and Subthreshold PTSD
Table 3 shows results of ANOVA and χ2 analyses of trauma exposure and psychiatric characteristics by PTSD screening status. Veterans with full PTSD endorsed the highest number of ACEs and direct trauma exposures. These veterans were also most likely to endorse military sexual trauma and screen positive for most of the assessed psychiatric disorders. Veterans with subthreshold PTSD endorsed a higher number of ACEs and direct trauma exposures relative to those in the no PTSD group. These veterans were also more likely to endorse military sexual trauma and screen positive for most psychiatric disorders. Veterans with full PTSD were most likely to endorse interpersonal violence as their index trauma, followed by veterans in the subthreshold group. Veterans with no PTSD were most likely to endorse disaster/accident as their index trauma, followed by the subthreshold group.
Table 4 shows results of multivariable analyses of associations between PTSD screening status and lifetime and current mental health variables. Relative to veterans with no PTSD, those with full and subthreshold PTSD had elevated odds of most of the psychiatric screening measures assessed (odds ratio [OR] range for full PTSD = 1.67–11.08; OR range for subthreshold PTSD = 1.71–3.26). These veterans also had greater odds of previously attempting suicide (ORs = 2.11 and 2.22, respectively), endorsing current SI (ORs = 5.25 and 2.28, respectively), and to have ever been and currently be engaged in mental health treatment (ORs = 5.29 and 2.32, and 5.23 and 3.32, respectively). Relative to veterans with subthreshold PTSD, those with full PTSD were more likely to screen positive for lifetime MDD and AUD and current MDD, GAD, and SI (ORs = 1.83–4.56) and had greater odds of lifetime and current mental health treatment (ORs = 2.42 and 1.76, respectively).
Functional Correlates of Full and Subthreshold PTSD
Table 5 shows the results of multivariate analyses of mental, psychosocial, and cognitive functioning by lifetime PTSD screening status. After adjusting for sociodemographic characteristics, military status, mental health treatment, trauma exposure, and lifetime psychiatric and substance use disorders, veterans with subthreshold PTSD scored significantly lower than those with no PTSD on these measures (Cohen d range=0.18–0.28). Larger effect size differences were observed between veterans with full PTSD relative to those with no PTSD (d range=0.49–0.61) and subthreshold PTSD (d range=0.44–0.69).
DISCUSSION
Using data from a large, contemporary, nationally representative sample of US military veterans and a recently proposed working case definition of subthreshold PTSD, which accounts for DSM-5 PTSD symptom criteria as well as symptom duration and distress/impairment,16 the present study examined the epidemiology of subthreshold PTSD. Results revealed that 3.9% of veterans had subthreshold PTSD in their lifetimes, which is consistent with the 3.5% prevalence observed in a comprehensive global study of 13 countries and nearly 24,000 trauma-exposed individuals, which used clinical interviews to estimate the prevalence of DSM-5 subthreshold PTSD on the basis of meeting diagnostic criteria for either 2 or 3 PTSD symptom clusters.7 Based on population benchmarks from the US Census Bureau,13 our observed 3.9% prevalence of subthreshold PTSD suggests that, in addition to the approximately 1.5 million US veterans with full PTSD, an additional approximately 700,000 veterans may be affected by clinically significant symptoms of PTSD in their lifetimes and may be at heightened risk of developing full PTSD.11
Consistent with prior population-based studies of US military veterans,4,9,29 subthreshold PTSD was associated with intermediately elevated odds of screening positive for lifetime and current MDD, lifetime DUD, and current MDD, GAD, and AUD, relative to veterans with no PTSD. Veterans with full PTSD generally showed an even greater elevation in odds for the majority of these psychiatric disorders, though veterans with subthreshold vs full PTSD did not differ with respect to odds of lifetime DUD and current AUD. The overall increased likelihood of other psychiatric disorders in the full PTSD group could be related, in part, to the types of traumas experienced. Veterans with full PTSD were more likely to endorse interpersonal traumas such as assault as their index event, whereas veterans with subthreshold PTSD group were more likely to endorse noninterpersonal traumas, such as natural disasters, which is consistent with research linking interpersonal traumas to higher levels of distress and greater likelihood of developing PTSD.7,30,31 Veterans with full PTSD also endorsed higher rates of adverse childhood experiences and direct trauma burden. Higher rates of trauma exposure could have contributed to a process of “stress sensitization”32 whereby veterans with a history of full PTSD may have been more vulnerable to subsequent stressors and thus more likely to develop other mental health problems.
Veterans with subthreshold PTSD were more than twice as likely to endorse current SI relative to those with no PTSD, even after adjusting for sociodemographic, military, and trauma exposure variables, as well as lifetime psychiatric and substance use disorders. Moreover, the odds of having attempted suicide did not differ between veterans with subthreshold PTSD relative to those with full PTSD, with both groups being twice as likely as veterans with no PTSD to report this history. When considered alongside the finding that veterans with subthreshold PTSD were more likely than those with no PTSD to have ever and currently be engaged in mental health treatment, these findings suggest that subthreshold PTSD is associated with a clinically significant and enduring effect on mental health and that it may be an important, and overlooked, indicator of suicide risk and need for mental health treatment. Consistent with a dimensional conceptualization of PTSD,33 these findings support recent calls to add a subthreshold course specifier to the DSM-5,34 which may help inform suicide prevention efforts by enhancing risk stratification on the basis of the full spectrum of PTSD symptoms.
In line with prior work,8,9 after adjusting for the aforementioned covariates, subthreshold PTSD was also associated with moderate decrements in mental, psychosocial, and cognitive functioning (d’s ranged from 0.18 for mental functioning to 0.28 for psychosocial functioning), relative to the no PTSD and full PTSD groups. This “dose-response” association underscores the utility of assessing, monitoring, and treating PTSD symptoms in veterans who do not meet full diagnostic criteria for PTSD, as these symptoms may contribute to functional difficulties in various life domains. Increased identification of veterans with subthreshold PTSD may also help advance the overall goal of the Veterans Health Administration’s Whole Health initiative,35 which aims to promote overall functioning and well being in the veteran population.
The results of this study should be interpreted in the context of 2 limitations. First, although our case definition of subthreshold PTSD included the assessment of duration and distress/impairment in addition to symptom criteria, it relied on a self-report measure; assessment of PTSD symptoms and related measures using structured clinical interviews may yield differences in the prevalence and correlates of subthreshold and full PTSD. Second, consistent with the sociodemographic composition of the general US veteran population, our sample was primarily male, older, and non-Hispanic white. Further research is needed to examine the epidemiology of subthreshold PTSD in more sociodemographically diverse subsets of veterans, active-duty service members, and other trauma-exposed people.
Notwithstanding these limitations, this study provides an up-to-date characterization of the epidemiology of subthreshold PTSD using DSM-5 criteria in a nationally representative sample of US military veterans. Overall, results indicate approximately 4% of US veterans experience subthreshold PTSD in their lifetimes, which is associated with elevated psychiatric burden, suicide risk, and functional difficulties. They also underscore the need to detect, monitor, and possibly treat subthreshold PTSD in this population. Additional research is needed to elucidate the longitudinal course of subthreshold PTSD symptoms, identify biopsychosocial mechanisms underlying the development of subthreshold vs full PTSD, and evaluate the efficacy of trauma- and non–trauma focused treatments on mitigating subthreshold PTSD symptoms in veterans and other trauma-affected populations.
Article Information
Published Online: October 23, 2024. https://doi.org/10.4088/JCP.24m15465
© 2024 Physicians Postgraduate Press, Inc.
Submitted: June 13, 2024; accepted July 26, 2024.
To Cite: Fischer IC, Na PJ, Harpaz-Rotem I, et al. Prevalence, correlates, and burden of subthreshold PTSD in US veterans. J Clin Psychiatry. 2024;85(4):24m15465.
Author Affiliations: US Department of Veterans Affairs National Center for Posttraumatic Stress Disorder, VA Connecticut Healthcare System, West Haven, Connecticut (Fischer, Harpaz-Rotem, Pietrzak); Department of Psychiatry, Yale School of Medicine, New Haven, Connecticut (Fischer, Na, Harpaz-Rotem, Pietrzak); VA Connecticut Healthcare System, West Haven, Connecticut (Na); Behavioral Sciences Division, National Center for PTSD, Boston, Massachusetts (Marx); VA Boston Healthcare System, Boston, Massachusetts (Marx); Department of Psychiatry, Boston University Chobanian & Avedisian School of Medicine, Boston, Massachusetts (Marx); Department of Social and Behavioral Sciences, Yale School of Public Health, New Haven, Connecticut (Pietrzak).
Corresponding Author: Ian C. Fischer, PhD, US Department of Veterans Affairs National Center for Posttraumatic Stress Disorder, VA Connecticut Healthcare System, 950 Campbell Ave, West Haven, CT 06516 (ian.fischer@yale.edu).
Relevant Financial Relationships: Drs Fischer, Na, Harpaz-Rotem, Marx, and Pietrzak have no relevant conflicts to disclose.
Funding/Support: Preparation of this manuscript was supported in part by the US Department of Veterans Affairs Office of Academic Affiliations, Advanced Fellowship Program in Mental Illness Research and Treatment.
Role of the Funder/Sponsor: The US Department of Veterans Affairs had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.
Clinical Points
- Subthreshold PTSD prevalence estimate is 3.9% of US military veterans, and veterans with subthreshold PTSD have higher rates of psychiatric disorders, suicidal thoughts and behaviors, and functional difficulties relative to veterans without PTSD.
- Ongoing efforts to identify, monitor, and potentially treat veterans with subthreshold PTSD may help improve mental health and functioning and mitigate suicide risk in this population.
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