2.1. NSDUH and MHSS Clinical Interview Sampling and Weighting Methods

The MHSS clinical sample was selected from all adult NSDUH respondents who completed the interview in English from 2008 to 2012. Of the approximately 45,000 adults who completed the NSDUH interview annually from 2008 to 2012, approximately 44,000 respondents completed the interview in English. Adult respondents were selected for the MHSS clinical interview using a sampling algorithm. During the 5-year MHSS clinical study, approximately 8,600 respondents were selected to participate in the clinical interview, with 83.7 percent agreeing to participate,^a and 78.3 percent of those who had originally agreed to participate completing the interview. The final overall weighted response rate taking these two stages of nonresponse into account was 64.6 percent. A total of 5,653 respondents completed the MHSS clinical interview and were included in these analyses.^b

Analysis weights were created for the MHSS clinical sample. These weights adjusted the adult NSDUH main interview respondent analysis weights to account for the exclusion of respondents completing the Spanish version of the NSDUH interview, as well as for MHSS clinical interview nonresponse. The weights were also post-stratified to NSDUH control totals, and a final annual scaling factor was applied to the weights for all cases across the years 2008 to 2012 to account for the different annual clinical sample designs and sample sizes. These final weights were used to compute the disorder-level estimates and standard errors presented in this report. Further details on MHSS clinical study recruitment, sampling, and weighting procedures for 2008 to 2012 can be found in the MHSS operations report and the MHSS design and estimation report.^19,20

2.2. Data Collection

Clinical interviewers contacted MHSS clinical study participants by telephone, ensured the confidentiality and privacy of responses, obtained informed consent, and conducted interviews. The mean length of the interview was 72 minutes, with a median of 60 minutes. These interviews were conducted within 4 weeks of completing the NSDUH interview. Respondents were provided a $30 incentive for participating in the NSDUH interview and an additional $30 for the MHSS clinical interview. The Structured Clinical Interview for DSM-IV-TR Axis I Disorders (SCID-I)²¹ was administered over the telephone by master's- or doctoral-level clinically trained interviewers who had undergone extensive training with clinical supervisors and the developer of the SCID. To ensure that the highest standards of quality were met, all SCID interviews were reviewed by one or more doctoral-level clinical supervisors who were trained by and received ongoing consultation from SAMHSA and National Institute of Mental Health staff, as well as the SCID developer. Further details on MHSS training procedures for 2008 to 2012 and details about the SCID administration and quality control in the MHSS clinical study are available as part of several methodological reports.^13,20

The clinical interview consisted of a modified version of the SCID-I. The MHSS version of the SCID was modified in order to assess mental and substance use disorders experienced in the 12 months before the interview, based on diagnostic criteria from the DSM-IV-TR.²² As a semistructured clinical interview, the SCID contains structured, standardized questions that are read verbatim and sequentially. The MHSS clinical study interviewers also were instructed to ask unstructured follow-up questions tailored to each respondent. Interviewers coded the presence or absence of each symptom or disorder based on their clinical judgment and respondents' answers to both the structured and the unstructured questions.

Considered the "gold standard" in psychiatric assessment,^23,24 the SCID has demonstrated good reliability^25,26,27 and validity.^{28,29,30,31,32,33} The SCID has also been widely used as a clinical validation tool for other instruments used in studies such as the National Comorbidity Survey Replication (NCS-R),³⁴ the National Survey of American Life,³⁵ and the NSDUH substance use disorders reappraisal study.³⁶ Studies that compared telephone with face-to-face administration of the SCID have also found good reliability and validity for the telephone-administered SCID.^{37,38,39,40,41,42,43}

PTSD was one of the disorders assessed in the MHSS clinical study (see Appendix A for the SCID module used in the MHSS). The PTSD module assessed past year PTSD. To screen into this module, respondents had to affirm that they had been exposed to one or more PTEs in their lifetime (DSM-IV PTSD Criterion A1) and then affirm at least one of the DSM-IV Criterion B questions: (1) had re-experienced the traumatic event through recurrent nightmares, flashbacks, or intrusive thoughts; or (2) had gotten very upset when recalling the traumatic event (see Figure 2.1). In this report, these Criterion B symptoms are sometimes referred to as experiencing "recurrent upsetting memories or flashbacks" to facilitate clarity of reporting.

Figure 2.1

Assessment of Lifetime Exposure to One or More PTEs and Posttraumatic Stress in the MHSS Clinical Study.

2.3. Measures

The past year PTSD module included items to assess whether the traumatic event(s) in question met the DSM-IV PTSD Criteria A1 and A2 definitions of a traumatic event (i.e., that the event involved actual or threatened death or serious injury, or a threat to the physical integrity of self or others that was accompanied by a response that involved intense fear, helplessness, or horror). If both Criteria A1 and A2 were met, the respondent was then assessed for symptoms to meet Criterion B, which included having at least one of five re-experiencing symptoms in the past year. If Criteria A and B were met, respondents were assessed for meeting Criterion C, with at least three of seven avoidance symptoms experienced in the past year. If Criteria A, B, and C were met, respondents were assessed for Criterion D, which included reporting at least two of five hyperarousal symptoms in the past year. Adults meeting Criteria A through D then were asked questions assessing Criterion E, which included experiencing the symptoms for at least 1 month in the past year, and Criterion F, symptoms causing clinically significant impairment in the past year. Respondents affirming all PTSD Criteria A through F met the definition of past year PTSD. Respondents affirming all PTSD Criteria A and B as well as endorsing at least one symptom from Criterion C have been classified as having past year posttraumatic stress symptoms (PTSS) for the purpose of this study. Adults with PTSD were also included in the past year PTSS group.

For this analysis, four nonmutually exclusive measures of traumatic event exposure and posttraumatic stress were examined. These measures included the following:

1. Lifetime exposure to one or more PTEs (lifetime DSM-IV PTSD Criterion A1). This outcome will be called "exposure to one or more PTEs" throughout the remainder of this report. The current study estimates that 40.8 percent of adults aged 18 or older have had lifetime exposure to one or more PTEs.
2. Lifetime exposure to one or more PTEs followed by recurrent upsetting memories or flashbacks (lifetime DSM-IV PTSD Criterion A1 and one of the assessed lifetime Criterion B symptoms).
3. Past year PTSS (including PTSD) (past year DSM-IV PTSD Criteria A1, A2, and B, plus at least one symptom from Criterion C). This outcome will be called "past year PTSS" henceforth. The current study estimates that just over 2 percent (2.1 percent) of adults have past year PTSS and that 5.2 percent of adults with one or more lifetime PTEs have past year PTSS.
4. Past year PTSD (past year DSM-IV PTSD Criteria A1, A2, B, C, D, E, and F). The current study estimates that 0.7 percent of adults have past year PTSD and that, among adults with one or more lifetime PTEs, 1.8 percent have past year PTSD.

These measures were selected to compare correlates of lifetime exposure to one or more PTEs and past year posttraumatic stress with those reported in prior studies such as those conducted using the NCS-R and the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC) data.^4,5 The correlates of lifetime exposure to one or more PTEs can be compared with those studied using NESARC data because NESARC used a similar criterion to define PTE exposure (lifetime PTSD Criterion A1). However, the MHSS SCID was modified in such a way that it does not enable comparisons with correlates of lifetime PTSS or PTSD found in other studies. Instead, the lifetime exposure to one or more PTEs followed by recurrent upsetting memories or flashbacks variable serves as a proxy for having at least some level of lifetime posttraumatic stress after PTE exposure. The definition of past year PTSS was created to be similar to the "subclinical" PTSD variable used by NESARC, with the acknowledgment that the definitions are not the same. Unlike NESARC, the skip pattern in the MHSS directed the interviewer out of the PTSD module as soon as a respondent did not fully meet one of the PTSD criteria (e.g., Criterion D questions were not asked unless Criteria A and B were met and at least three of the Criterion C questions were affirmed; Criterion E questions were not asked unless Criteria A, B, and C were met and at least two Criterion D questions were affirmed). Therefore, the presence of Criterion D symptoms is assessed only among people meeting Criteria A, B, and C; those who failed to meet earlier criteria would have exited the module. The MHSS used DSM-IV criteria to define past year PTSD, similar to the criteria used to define past year PTSD in the NCS-R, although the MHSS also included screener questions to enter the past year PTSD assessment module.

The potential correlates of exposure to one or more PTEs and posttraumatic stress were selected based on a review of the literature and data available in NSDUH. Variables selected included demographic and socioeconomic characteristics, self-reported receipt of a physical or mental health diagnosis, and mental health and substance use indicators.

2.4. Data Analysis

Comparisons were made between adults with lifetime exposure to one or more PTEs and adults with posttraumatic stress for this report using SCID data from 5,653 MHSS clinical interviews conducted between 2008 and 2012. Because the annual sample sizes in the clinical study are small, annual estimates for each comparison are not feasible; therefore, estimates for each comparison are based on the combined 5-year MHSS clinical sample. Data on the characteristics (such as demographic, socioeconomic, and health conditions) of the MHSS respondents were obtained as part of the NSDUH main interviews for each of these respondents. These data were used to

• describe adults with lifetime exposure to one or more PTEs (e.g., by looking at the distribution of characteristics such as age, gender, etc., among adults with lifetime exposure to one or more PTEs and comparing with characteristics among the total adult population), lifetime exposure to one or more PTEs followed by upsetting memories and flashbacks, past year PTSS, and past year PTSD (Section 3.1);
• compare the prevalence estimates of lifetime exposure to one or more PTEs, lifetime exposure to one or more PTEs followed by upsetting memories and flashbacks, past year PTSS, and past year PTSD between levels of these characteristics to understand characteristics of individuals with versus without lifetime exposure to PTEs and with versus without each posttraumatic stress measure (Section 3.2); and
• examine the prevalence of mental health and substance use issues by lifetime exposure to one or more PTEs and posttraumatic stress variables (including PTSD) (Section 3.3).

It should be noted that Section 3.2 describes the prevalence of lifetime exposure to one or more PTEs among all adults and describes the prevalence of various postraumatic stress measures among all adults and among adults who had lifetime exposure to one or more PTEs by subpopulations of interest. Likewise, Section 3.3 describes the prevalence of mental health and substance use issues by lifetime exposure to one or more PTEs and posttraumatic stress measures among all adults and among adults with lifetime exposure to one or more PTEs. These separate sets of analyses enable the examination of factors associated with posttraumatic stress measures among all adults and factors associated with posttraumatic stress among adults with lifetime exposure to one or more PTEs.

Estimates, along with the associated standard errors (SEs) via a Taylor series linearization approach, were computed using SUDAAN^® to account for analysis weights and complex survey design.^c,19,20,44 The SEs were used to identify unreliable estimates and test for the statistical significance of differences between estimates across each correlate level.^d,45 An alpha level of 0.05 was set as an indicator of statistical significance. A simple Bonferroni adjustment was applied when more than two levels were compared, by taking the standard .05 p value and dividing it by the number of pairwise comparisons.^e,46

The proportion of missing data and the imputation strategy differed for each variable. The age variable collected from the NSDUH main interview has no missing data. For some of the variables from the NSDUH main interview included in these analyses (e.g., gender, race/ethnicity), missing values were imputed using the predictive mean neighborhood method.^f,47,48 For poverty status, also taken from the main NSDUH interview, all the respondents aged 18 to 22 who lived in college dormitories were assigned missing values. Respondents with missing data on a particular comorbid mental or physical condition were excluded from that particular bivariate analysis; missing data were less than 1 percent for each of these variables. For variables collected from the MHSS clinical interview, missing values were not imputed. If one or more variables needed to make a combined exposure to PTE or posttraumatic stress variable were missing, the variable itself was coded as missing. The proportion of missing values for the exposure to PTE and posttraumatic stress variables is small (i.e., less than 1 percent).

3.1. Comparisons of Demographic and Socioeconomic Characteristics of Adults Overall with Adults Who Had Exposure to One or More Lifetime PTEs and Posttraumatic Stress

Table 3.1 presents demographic and socioeconomic characteristics of all adults alongside those of adults with exposure to one or more lifetime PTEs, adults with lifetime PTEs followed by upsetting memories or flashbacks,^g adults with past year PTSS,^h and adults with past year PTSD. P values for differences in these characteristics between all adults and adults with each PTE exposure/posttraumatic stress measure are included in Appendix Table B1.

Table 3.1

Distribution of Demographic and Socioeconomic Characteristics among All Adults Aged 18 or Older, by Lifetime Exposure to One or More PTEs and Posttraumatic Stress: MHSS Clinical Study, 2008-2012.

Compared with all adults, those with lifetime exposure to one or more PTEs are less likely to be in the youngest age category (18-25 years) (e.g., 11.5 percent of adults with a lifetime exposure to one or more PTEs were aged 18-25 years, compared with 14.7 percent of all adults) and more likely to be not Hispanic/Latino white and veterans. Adults with lifetime exposure to one or more PTEs followed by upsetting memories or flashbacks are more likely to be older, female, not Hispanic/Latino white and less likely to be employed full time than all adults. The age distribution of adults with past year PTSS significantly differed from the age distribution among all adults (e.g., adults with past year PTSS were more likely to be aged 26-49 years and less likely to be aged 50 or older than all adults). Adults with past year PTSS also are more likely to live at less than 100 percent of the poverty level and to have family incomes of less than $20,000 per year and less likely to be employed full time and to have family incomes of more than $75,000 per year than all adults.

3.2. Prevalence of Exposure to One or More Lifetime PTEs and Posttraumatic Stress by Demographic and Socioeconomic Characteristics and Physical and Behavioral Health Conditions among Adults

Lifetime Exposure to One or More PTEs

Table 3.2 provides estimates of lifetime PTE exposure and related posttraumatic stress sequelae for all four of the examined outcomes (lifetime exposure to one or more PTEs and each posttraumatic stress measure) for each demographic and socioeconomic variable. P values for each comparison are listed in Appendix Table B2. Estimated percentages of adults with lifetime exposure to one or more PTEs were higher among adults aged 26 to 49 (41.6 percent) and adults aged 50 or older (42.9 percent) than among adults aged 18 to 25 (32.0 percent; Table 3.2). Likewise, higher percentages of not Hispanic/Latino white adults were exposed to a lifetime PTE than not Hispanic/Latino other⁴⁹ adults (43.9 vs. 26.8 percent), and a higher percentage of veterans were exposed to one or more lifetime PTEs than nonveterans (60.3 vs. 38.1 percent). Lifetime exposure to one or more PTEs did not vary by gender, education, employment, poverty status, family income level, or marital status. The percentage of adults with lifetime exposure to one or more PTEs was significantly higher among adults with the following medical conditions assessed in the MHSS than among their counterparts who did not have these conditions: asthma, high blood pressure, sinusitis, ulcer, anxiety, and depression.

Table 3.2

Lifetime Exposure to One or More PTEs and Posttraumatic Stress among Adults Aged 18 or Older, by Demographic and Socioeconomic Characteristics: MHSS Clinical Study, 2008-2012 (n = 5,653).

Past Year PTSS

Among all adults, the past year estimate of PTSSⁱ (which, as previously mentioned, includes adults with PTSD) was higher for adults aged 26 to 49 versus those aged 50 or older (2.7 vs. 1.5 percent) and for females than males (2.7 vs. 1.4 percent; Table 3.2). Adults with current "other" employment status (which includes individuals on disability)⁵¹ had higher percentages of past year PTSS than adults working full time (3.0 vs. 1.4 percent). Adults at less than 100 percent of the federal poverty level and adults with family incomes of less than $20,000 per year, respectively, had higher past year PTSS estimates than adults at 200 percent or greater of the poverty level and adults with family incomes of $50,000-$74,999 and $75,000 or higher. P values for each comparison are listed in Appendix Table B2.

Among adults with lifetime exposure to one or more PTEs, significant differences in past year PTSS by age, gender, employment status, and income (but not living below the federal poverty level) followed patterns similar to those found among all adults. The past year estimated percentage of adults with PTSS was higher for adults aged 18 to 25 and adults aged 26 to 49 than for adults aged 50 or older (7.3 and 6.4 vs. 3.5 percent, respectively; Table 3.3). Females had a higher percentage of past year PTSS than males (6.9 vs. 3.5 percent, respectively). Adults with "other" employment status had higher estimates of past year PTSS than adults working full time (7.5 vs. 3.5 percent). Adults with family incomes of less than $20,000 per year had higher past year estimates of PTSS than adults with family incomes of $75,000 or higher (9.3 vs. 3.2 percent).⁵² P values for each nonsuppressed comparison are listed in Appendix Table B3.

Table 3.3

Past Year PTSS and PTSD among Adults Aged 18 or Older with Lifetime Exposure to One or More PTEs,¹ by Demographic and Socioeconomic Characteristics: MHSS Clinical Study, 2008-2012 (n = 2,679).

3.3. Substance Use and Mental Health Indicators among Adults by Lifetime Exposure to One or More PTEs and Posttraumatic Stress

Table 3.4 displays the full set of estimates of each substance use, mental health, and physical health indicator by lifetime exposure to PTEs and presence of posttraumatic stress. Figure 3.1 and Figure 3.2 display these associations for key substance use and mental health indicators in graphical form.

Table 3.4

Substance Use, Mental Health, and Physical Health Indicators among Adults Aged 18 or Older, by Lifetime Exposure to One or More PTEs and Posttraumatic Stress: MHSS Clinical Study, 2008-2012 (n = 5,653).

Figure 3.1

Key Substance Use Indicators among Adults Aged 18 or Older, by Lifetime Exposure to One or More PTEs: MHSS Clinical Study, 2008-2012 (n = 5,653).

Figure 3.2

Mental Health Indicators among Adults Aged 18 or Older, by Lifetime Exposure to One or More PTEs: MHSS Clinical Study, 2008-2012 (n = 5,653).

Lifetime Substance Use

The prevalence of lifetime illicit drug use was higher among adults with versus without lifetime exposure to one or more PTEs (60.0 vs. 45.9 percent; Table 3.4). Similarly, lifetime illicit drug use was higher among adults with versus without lifetime exposure to one or more PTEs followed by recurrent upsetting memories or flashbacks (the second trauma measure examined; 59.4 vs. 50.3 percent) and those with versus without past year PTSS (including PTSD, the third trauma measure examined; 70.3 vs. 51.3 percent). Similar results were observed for lifetime illicit drug use excluding marijuana.^54,55 Comparisons of substance use prevalence among adults with versus without PTSD are not made because of data suppression due to the imprecision of estimates.

The significant associations between lifetime substance use indicators, exposure to one or more PTEs, and posttraumatic stress among adults with exposure to one or more PTEs had slightly different patterns than those among all adults. Among adults with lifetime exposure to one or more PTEs, the prevalence of illicit drug use other than marijuana, but not all illicit drug use, was higher among those with versus without past year PTSS (including PTSD; Table 3.5). Like the estimates made among all adults, associations between lifetime substance use indicators and past year PTSD were suppressed.

Table 3.5

Substance Use, Mental Health, and Physical Health Indicators among Adults Aged 18 or Older with Lifetime Exposure to One or More PTEs,¹ by Past Year PTSS and PTSD: MHSS Clinical Study, 2008-2012 (n = 2,679).

Past Year Substance Use

The estimates for several past year substance use indicators were higher among adults with versus without lifetime exposure to one or more PTEs. They were also higher among adults with lifetime exposure to one or more PTEs followed by recurrent upsetting memories or flashbacks and those with past year PTSS (including PTSD; Table 3.4). For example, the estimates of past year illicit drug use, marijuana use, nonmedical use of psychotherapeutics, and tobacco use⁵⁶ were higher for those with versus without lifetime exposure to one or more PTEs (18.8 vs. 13.3 percent, 14.7 vs. 10.1 percent, 7.0 vs. 4.9 percent, and 42.2 vs. 30.6 percent, respectively). Likewise, the estimates of past year any substance use disorder and of past year receipt of substance use treatment⁵⁷ were higher for those with versus without lifetime exposure to one or more PTEs (10.1 vs. 7.7 percent and 1.9 vs. 1.0 percent, respectively).

Adults with versus without lifetime exposure to one or more PTEs followed by recurrent upsetting memories or flashbacks were more likely to use tobacco, have illicit drug dependence or abuse, or receive substance use treatment in the past year (42.2 vs. 34.1 percent, 4.4 vs. 2.3 percent, and 2.3 vs. 1.2 percent, respectively; Table 3.4). The estimates of all past year substance use indicators, except use of illicit drugs, were significantly higher for those with versus without past year PTSS. No significant differences in past year substance use indicators were noted between adults with versus without past year PTSD, although several of the estimates were suppressed.

Table 3.5 displays the full set of estimates of each substance use, mental health, and physical health indicator tested by past year PTSS status among adults with lifetime exposure to one or more PTEs, whereas Figure 3.3 and Figure 3.4 display these associations for key substance use and mental health indicators in graphical form.

Figure 3.3

Key Substance Use Indicators among Adults Aged 18 or Older with Lifetime Exposure to One or More PTEs, by Past Year PTSS: MHSS Clinical Study, 2008-2012 (n = 2,679).

Figure 3.4

Mental Health Indicators among Adults Aged 18 or Older with Lifetime Exposure to One or More PTEs, by Past Year PTSS: MHSS Clinical Study, 2008-2012 (n = 2,679).

The significant associations between substance use indicators and past year PTSS (including PTSD) among adults with lifetime exposure to one or more PTEs (Table 3.5) followed patterns similar to associations examined among all adults. Among adults with lifetime exposure to one or more PTEs, those with past year PTSS had higher prevalence estimates of past year tobacco use, alcohol dependence or abuse, illicit drug dependence or abuse, any substance use disorder, and receipt of substance use treatment than those without past year PTSS. There were no significant differences between those with versus without past year PTSS among adults with lifetime exposure to one or more PTEs for past year illicit drug use, illicit drug use other than marijuana, marijuana use, and nonmedical use of psychotherapeutics. Other estimates for past year substance use and PTSD were suppressed.

Lifetime Physical Health Conditions

Among all adults, the estimates of lifetime asthma, heart disease, high blood pressure, pneumonia, sexually transmitted disease, sinusitis, sleep apnea, and ulcer were significantly higher among adults with lifetime exposure to one or more PTEs than adults without (Table 3.4 and Figure 3.5). Similarly, the estimates of lifetime asthma, bronchitis, diabetes, high blood pressure, sexually transmitted disease, sinusitis, and ulcer were significantly higher among those with versus without lifetime exposure to one or more PTEs followed by recurrent upsetting memories or flashbacks. Lifetime estimates of asthma, bronchitis, sexually transmitted disease, sleep apnea, and ulcer were higher among adults with past year PTSS than adults without. Most estimates of physical conditions examined by past year PTSD status were suppressed; however, adults with past year PTSD were more likely than those without to have tinnitus (8.3 vs. 2.1 percent, respectively).

Figure 3.5

Lifetime Physical Health Conditions among Adults Aged 18 or Older That Significantly (p < .05) Differ, by Lifetime Exposure to One or More PTEs: MHSS Clinical Study, 2008-2012 (n = 5,653).

Among adults with lifetime exposure to one or more PTEs, the estimates for each of the physical health conditions examined did not significantly differ by past year PTSS status, and most estimates were suppressed by PTSD status (Table 3.5).

4.1. Summary of Results

This study provides the most recent investigation of characteristics of people with lifetime exposure to one or more potentially traumatic events (PTEs) and posttraumatic stress using nationally representative data. Furthermore, this study examines the extent of mental health issues and substance use measures by each of the four trauma-related measures among U.S. adults aged 18 or older and among those exposed to lifetime exposure to one or more PTEs.

Several correlates of lifetime exposure to one or more PTEs and posttraumatic stress variables were identified (see Table 4.1 for a summary of demographic and socioeconomic correlates of each of these variables). For example, lifetime exposure to one or more PTEs was associated with increased age, not Hispanic/Latino white race/ethnicity (compared with not Hispanic/Latino "other"), and veteran status, but not with gender and other demographic and socioeconomic variables studied. In addition, past year posttraumatic stress symptoms (PTSS) estimates (which also included those with past year posttraumatic stress disorder [PTSD]) were higher among adults aged 26 to 49 than among adults aged 50 or older, among females as compared with males, among those with "other" employment (which includes disability, as compared with those who were employed full time or unemployed), and for lower family income both among all adults and among adults with lifetime exposure to one or more PTEs. Among all adults, past year PTSD was associated with not Hispanic/Latino white race/ethnicity (compared with not Hispanic/Latino black/African American), "other" employment status (which includes disability, as compared with those who were employed full time), and lower family income, but not with gender, age, veteran status, or the other demographic or socioeconomic variables studied.

Table 4.1

Summary of Significant Differences in Percentages of Lifetime Exposure to One or More PTEs and Posttraumatic Stress, by Demographic and Socioeconomic Characteristics among All Adults Aged 18 or Older and among Adults Aged 18 or Older with Lifetime Exposure (more...)

Most correlates of past year PTSD among adults with exposure to one or more PTEs were similar to correlates among all adults, with the exception that no association was found between race/ethnicity and past year PTSD after adjusting for exposure to one or more PTEs.

The prevalence of many of the substance use, mental health, and physical health indicators was higher among adults with versus without lifetime exposure to one or more PTEs, with lifetime exposure to one or more PTEs followed by recurrent upsetting memories or flashbacks, and with past year PTSS (including PTSD; see Table 4.2 for a summary of significant associations).

Table 4.2

Summary of Significant Differences in Percentages of Substance Use and Mental Health Measures, by Lifetime Exposure to One or More PTEs and Posttraumatic Stress, among All Adults Aged 18 or Older and among Adults Aged 18 or Older with Lifetime Exposure (more...)

Associations between past year PTSS and substance use or mental health indicators were similar among all adults and among adults with lifetime exposure to one or more PTEs. For example, the prevalence of past year suicidal thoughts was more than 6 times as high among all adults with versus without past year PTSS (21.8 vs. 3.3 percent) and among adults with lifetime exposure to one or more PTEs with versus without past year PTSS (21.8 vs. 3.5 percent). These findings suggest that associations between past year PTSS and mental health and substance use indicators persist even after controlling for lifetime exposure to one or more PTEs. Significant associations found between physical health conditions and past year PTSS among all adults were not significant after controlling for lifetime exposure to one or more PTEs. All of the comparisons between physical conditions and PTSD were suppressed; however, low sample sizes and corresponding high standard errors may partly explain why significant differences were not found.

4.2. Comparison with Other Studies

This report did not statistically compare estimates of lifetime exposure to one or more PTEs and subsequent posttraumatic stress estimates from the Mental Health Surveillance Study (MHSS) with those found in prior U.S. nationally representative surveys for several reasons. Two of the outcome variables examined, lifetime exposure to one or more PTEs followed by flashbacks or recurrent upsetting memories and past year PTSS, as they were defined in the MHSS, were not comparable with any measures reported in prior nationally representative surveys. Differences in the estimates of the other two variables, lifetime exposure to one or more PTEs and PTSD, found in the current study compared with prior estimates may be due to variation in the definition and assessment methods of these variables in other studies reported in the literature.

• Interviewer Qualifications: Both the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC) and the National Comorbidity Survey Replication (NCS-R) used fully structured interviews to assess and define exposure to PTEs and posttraumatic stress measures in which the lay interviewers did not have input into the determination of whether event exposure was sufficiently traumatic to meet criteria from the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV).² In the MHSS, the clinical interviewers used clinical judgment in coding exposure to a PTE and the presence of posttraumatic stress. This enabled clinical interviewers to differentiate very stressful events from actual Criterion A PTEs, thereby reducing the possibility of false-positive reporting of symptoms.
• Screening Questions: Unlike other surveys, the MHSS included a set of screening questions in order to advance into the PTSD module. The MHSS respondents had to affirm lifetime PTSD Criterion A1 and either of the lifetime Criteria B questions asked (i.e., that exposure to a PTE was followed by recurrent upsetting memories or flashbacks) to enter the Structured Clinical Interview for DSM Disorders module to assess past year PTSD. The NCS-R did not include a skip pattern based on screener questions. It is possible that individuals responded negatively to screening questions in the MHSS in order to hasten the survey, which may account for some reduction in the prevalence estimates.
• Difference in Exposure to PTE Examples: The instruments used to assess exposure to PTEs differed with respect to the number and type of PTE examples provided in the first question of the assessment. For example, the MHSS gave examples of PTE exposure in a single statement that began "…things like…," whereas NESARC provided a much more inclusive series of questions about specific exposures to PTEs. These types of differences may affect how an individual responds to questions about PTE exposure across surveys.
• Differences in PTE Definition: The MHSS and NESARC used DSM-IV PTSD Criterion A1 (the person experienced, witnessed, or was confronted with one or more PTEs that involved actual or threatened death or serious injury, or a threat to the physical integrity of self or others) to define lifetime exposure to one or more PTEs, whereas the NCS-R, the Collaborative Psychiatric Epidemiology Surveys (CPES), and the National Survey of American Life required both DSM-IV PTSD Criteria A1 and A2 (the person's response to the PTE exposure involved intense fear, helplessness, or horror). The inclusion of the additional A2 Criterion by these surveys would suggest that a lower proportion of respondents would meet criteria for exposure to one or more PTEs than in the MHSS and NESARC, potentially changing the pattern of significant correlates. However, the definition of PTE exposure for past year PTSS and PTSD in the MHSS did require the respondent to meet both Criteria A1 and A2 and used the same DSM-IV criteria (A1, A2, B, C, D, E, and F) as the NCS-R, so correlates of these indicators should be similar. It is important to note that the definition of PTSD in the recently released DSM-5 dropped Criterion A2 because research showed that requiring it did not improve diagnostic accuracy.⁶⁶

The MHSS analyses found some of the same correlates of lifetime exposure to one or more PTEs as other prior U.S. nationally representative surveys. For example, this study demonstrated that not Hispanic/Latino white adults had higher estimates of lifetime exposure to one or more PTEs than not Hispanic/Latino "other" adults.⁸ It should be noted, however, that one aspect of the MHSS sampling frame may differentially affect comparisons of estimates between people across race/ethnicity groups. The MHSS interview was administered only in English, so the MHSS sample drawn from the larger NSDUH sample did not include those who completed the NSDUH interview in Spanish (i.e., were unable to complete an interview in English). Thus, the estimates produced by the MHSS sample may not be fully representative of the U.S. civilian, noninstitutionalized population.

Consistent with NESARC findings,⁶⁷ the MHSS analyses also showed that lifetime exposure to one or more PTEs was associated with several health conditions and various indicators of mental health and substance use. Findings from the MHSS, however, found that estimated percentages of adults with lifetime exposure to one or more PTEs were higher among adults aged 26 to 49 and adults aged 50 or older than among adults aged 18 to 25, which has not been reported in prior U.S. nationally representative surveys.

For past year PTSS, prior studies have found females to have higher estimates of lifetime past year PTSS than males; the MHSS found a significant association between gender and past year PTSS as well. These analyses also identified significant associations between past year PTSS and several lifetime health conditions, mental health problems, and substance use indicators, which are consistent with some of the findings from NESARC that focused on associations with lifetime PTSS. The NESARC definition of lifetime PTSS, however, did not also include those with lifetime PTSD, so it was measured somewhat differently than in the MHSS. Finally, analyses of the MHSS data indicated that the percentage of adults with past year PTSS was higher among younger adults, those living in poverty and with low family income, and adults with "other" types of employment (including those on disability, as compared with those who were employed full time), which had not been reported previously in U.S. nationally representative surveys.

Correlates of PTSD identified in this study have similarities and differences compared with those found in the extant literature. For example, analyses of the MHSS found no differences in past year PTSD by gender, contrary to the NESARC study findings.^5,10 In addition, not Hispanic/Latino white adults in these analyses had higher past year estimates of PTSD than not Hispanic/Latino black/African American adults, which had not been reported in the NESARC (which only reported lifetime PTSD correlates) or NCS-R studies.^3,5 This study did note a significant association between PTSD and employment, replicating CPES lifetime PTSD correlate findings,⁹ and income, which was consistent with NESARC and NCS-R findings examining lifetime PTSD as a correlate.^3,5 This study was unable to examine differences in past year estimates of various indicators of substance use, mental health problems, and physical health conditions by past year PTSD due to small sample sizes.

4.3. Strengths and Limitations

This study uses recent, nationally representative data to examine estimates and correlates of lifetime exposure to one or more PTEs and subsequent posttraumatic stress, including past year PTSS and PTSD. In the MHSS, trained clinical interviewers assessed lifetime exposure to one or more PTEs and subsequent posttraumatic stress, which allowed them to ask unstructured follow-up questions tailored to each respondent. This enabled the interviewers to use clinical judgment for determining the presence of lifetime exposure to one or more PTEs and posttraumatic stress measures. Thus, assessment of lifetime exposure to one or more PTEs and posttraumatic stress was not dependent upon the respondents' ability to understand the context of their experiences and behaviors. This is in contrast to fully structured instruments, which do not allow for clinicians to clarify if exposure to one or more PTEs reported by a respondent met Criterion A requirements.

Moreover, by focusing some of the analyses on the subset of adults who had lifetime exposure to one or more PTEs, it was possible to begin examining indicators of the progression from PTE exposure to the development of posttraumatic stress, including PTSD.

In addition to MHSS interviews being conducted in English only, another important caveat in interpreting the findings from the MHSS and other U.S. nationally representative surveys that have provided information about correlates of exposure to PTEs and posttraumatic stress involves the household-based nature of the sampling designs, which precludes the examination of some populations at higher risk for trauma exposure such as people living in institutions, homeless people not living in shelters, and active duty military personnel. Estimates from the active duty population participating in the 2008 Department of Defense Survey of Health Related Behaviors Among Active Duty Military Personnel found that nearly 11 percent of individuals on active duty screened positive for posttraumatic stress⁶⁸ with sufficient PTSD symptoms in the past 30 days to warrant further diagnostic testing.⁶⁹ The use of the symptom screener rather than a diagnostic instrument suggests that this estimate captured individuals who may have either PTSS or PTSD. Additionally, this descriptive study focuses on correlates of PTSS to better characterize these adults. However, no covariates or potential confounding influences were adjusted for in these analyses, no temporality can be established, and no causal influences can be suggested based upon this research.

This study is important because trauma exposure and PTSD are associated with significant social, personal, and economic costs.⁷⁰ Trauma exposure and resulting posttraumatic stress both affect various aspects of physical and mental health, as well as treatment approaches. Because not everyone exposed to a PTE develops negative sequelae, it is important to identify factors that increase or decrease the risk of developing PTSS, including PTSD, as targets for prevention interventions. It is estimated that nearly half of adults (42.6 percent) with PTSD do not receive mental health treatment, and among those who do, only 40.4 percent are receiving minimally adequate treatment (23.2 percent of all adults with PTSD).⁷¹

Future research using multivariable modeling to control for potential confounding and additional research focusing on the examination of patterns of remission and risk factors for not remitting will be needed to identify important treatment targets. This investigation contributes to the Substance Abuse and Mental Health Services Administration's effort to monitor the extent of trauma and posttraumatic stress symptoms in the nation, determine associations with mental health and substance use problems as well as other deleterious effects, and develop and implement effective prevention, treatment, and recovery and resiliency support services for trauma and related sequelae.

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