CUMULATIVE TRAUMAS AND RISK THRESHOLDS: 12-MONTH PTSD IN THE WORLD MENTAL HEALTH (WMH) SURVEYS
Abstract
Background
Clinical research suggests that posttraumatic stress disorder (PTSD) patients exposed to multiple traumatic events (TEs) rather than a single TE have increased morbidity and dysfunction. Although epidemiological surveys in the United States and Europe also document high rates of multiple TE exposure, no population-based cross-national data have examined this issue.
Methods
Data were analyzed from 20 population surveys in the World Health Organization World Mental Health Survey Initiative (n 51,295 aged 18+). The Composite International Diagnostic Interview (3.0) assessed 12-month PTSD and other common DSM-IV disorders. Respondents with 12-month PTSD were assessed for single versus multiple TEs implicated in their symptoms. Associations were examined with age of onset (AOO), functional impairment, comorbidity, and PTSD symptom counts.
Results
19.8% of respondents with 12-month PTSD reported that their symptoms were associated with multiple TEs. Cases who associated their PTSD with four or more TEs had greater functional impairment, an earlier AOO, longer duration, higher comorbidity with mood and anxiety disorders, elevated hyper-arousal symptoms, higher proportional exposures to partner physical abuse and other types of physical assault, and lower proportional exposure to unexpected death of a loved one than cases with fewer associated TEs.
Conclusions
A risk threshold was observed in this large-scale cross-national database wherein cases who associated their PTSD with four or more TEs presented a more “complex” clinical picture with substantially greater functional impairment and greater morbidity than other cases of PTSD. PTSD cases associated with four or more TEs may merit specific and targeted intervention strategies. Depression and Anxiety 31:130–142, 2014.
INTRODUCTION
Although the diagnosis of posttraumatic stress disorder (PTSD) requires exposure to at least one traumatic event (TE), exposure to multiple TEs is common in clinical populations. In accordance with diagnostic criteria, epidemiologic studies typically assess PTSD only in relation to an index TE. However, consistent with clinical experience, more comprehensive surveys find that the majority of respondents with PTSD report exposure to multiple TEs over the life course.[1–3] The National Comorbidity Survey, for instance, showed that in the United States 64% of the population exposed to TEs were exposed to more than one TE and that 20% of males and 11% of females were exposed to three or more TEs.[1,4]
There is some suggestion in the literature that cases of PTSD whose symptoms are associated with multiple TEs, including both multiple types of TEs and repeated exposure to the same TE (e.g., chronic childhood abuse), have greater morbidity and dysfunction,[5–9] although these studies largely involve treatment-seeking samples in which there may be a referral bias.[10] The few existing community epidemiological studies on this topic have been limited to mostly adolescent samples in the United States or Europe and have not focused on persons with 12-month PTSD.[11–14] To our knowledge, no large-scale cross-national population-based survey has yet examined the possibility of added risk of dysfunction associated with multiple versus single types of TEs in adult 12-month PTSD. Such information would have immediate application for targeting prevention and intervention strategies, with particular relevance for economically developing countries in which fiscal constraints may limit mental healthcare access.[15,16]
The World Health Organization (WHO) World Mental Health (WMH) Surveys are the first population-based epidemiological studies to assess the 12-month prevalence of PTSD in large cross-national samples that have a full range of country income levels and use parallel methods. As part of the survey, respondents in 20 WMH countries who met criteria for PTSD in the past 12- months were asked to specify which of the lifetime TEs they had previously reported were implicated in their current symptoms. We examine the proportion of 12-month PTSD cases that reported multiple types of TEs, the proportion of those cases that attribute their PTSD to multiple types of TEs, and the associations of such reports with a variety of characteristics of 12-month PTSD.
METHODS AND MATERIALS
SAMPLES
Surveys were administered in 11 countries classified by the World Bank as high income (Belgium, France, Germany, Italy, Israel, Japan, Netherlands, New Zealand, Northern Ireland, Spain, United States) and nine classified as upper-middle income (Sao Paulo in Brazil, Bulgaria, Lebanon, Mexico, Romania, South Africa) or low/lower-middle income (Colombia, Ukraine, Beijing, Shanghai in the People's Republic of China [PRC]). All but six surveys were based on area probability household samples representative of the entire nation. The exceptions were surveys of all urbanized areas in two countries (Colombia, Mexico) and of specific Metropolitan areas in four other countries (Sao Paulo in Brazil; a series of cities in Japan; specific regions in Nigeria; Shenzhen in PRC) (see Table 6). Interviews were conducted face-to-face in respondent homes after obtaining informed consent. Human Subjects Committees monitored the surveys and approved recruitment and consent procedures in each country.
Interviews had two parts. Part I, administered to all respondents, assessed core disorders. All Part I respondents with a lifetime history of any core disorder plus a probability subsample of other respondents were administered Part II, which assessed other disorders and correlates. Part I was completed by 96,842 respondents.
Trauma and PTSD were assessed in Part II (N = 51,295). The Part II sample was weighted to adjust for the undersampling of Part I noncases and to adjust for sociodemographic/geographic discrepancies between sample and population based on census data. Part II response rates range from a low of 45.9% in France to 87.7% in Colombia (70.4% weighted average). Further details about WMH sample design are presented elsewhere.[17]
MEASURES
Translation
The WMH interview schedule was developed in English and translated into other languages using a standardized WHO translation, back-translation, and harmonization protocol described elsewhere.[18] Consistent interviewer training and quality control monitoring procedures were then used in all surveys to standardize question administration.[19]
TE Exposure
We assessed lifetime exposure to 29 TEs, including seven related to war and sectarian violence (e.g., combatant, civilian in a war zone), five types of physical assault (e.g., mugged), three types of sexual assault (e.g., rape, sexual assault), six types of trauma involving threats to physical integrity excluding violence (e.g., life-threatening accidents), traumatic death of a loved one, and five types of trauma involving threats to others or network events (e.g., life-threatening illness injury of loved one). Grouping of TEs is presented in Table A1. Respondents were asked to report lifetime exposure to each trauma on a hard copy list and to check off each endorsed event for future reference. Two additional open-ended questions asked about (1) any other TE not included on the list and (2) TE respondents did not wish to describe concretely. These 29 events were combined into 15 broader event categories for analysis (Table A2). This grouping has been published previously.[17] Positive responses were followed by probes to assess age when each event first occurred. The number of TEs was calculated as the number of different types of TEs endorsed by the respondent.
Mental Disorders
Mental disorders were assessed with the WHO Composite International Diagnostic Interview (CIDI),[18] a fully structured interview designed to generate diagnoses of com mon DSM-IV and ICD-10 mental disorders. DSM-IV criteria, including organic exclusions and diagnostic hierarchy rules, are used here. In addition to PTSD, we consider 12-month prevalences of five anxiety disorders (separation anxiety disorder, panic disorder and/or agoraphobia, generalized anxiety disorder (GAD), specific phobia, social phobia), two mood disorders (major depressive disorder (MDD)/dysthymia, bipolar disorder), four disruptive behavior disorders (attention-deficit/hyperactivity disorder (ADHD), oppositionaldefiant disorder (ODD), conduct disorder, intermittent explosive disorder (IED) and two substance disorders (alcohol and drug abuse with/without dependence).
As detailed elsewhere,[19] generally good concordance was found between diagnoses based on DSM-IV/CIDI and blinded SCID[20] clinical reappraisal interviews. Concordance for PTSD was in the moderate range,[21] with κ of 0.49 and area under the receiver operating characteristic curve (AUC) of 0.69. The two components of AUC, sensitivity and specificity, were 38.3 and 99.1, respectively, resulting in an LR+ of 42, which is well above the 10 threshold typically used to define screening scale diagnoses as definitive.[22] Consistent with the high LR+, positive predictive value (the proportion of CIDI cases confirmed by the SCID) of DSM-IV/CIDI PTSD was 86.1%, suggesting that the vast majority CIDI cases would independently be judged to have PTSD by trained clinicians.
PTSD was assessed twice in the DSM-IV/CIDI: once for symptoms associated with the respondent's self-selected worst lifetime trauma and a second time for symptoms associated with one other lifetime trauma selected using a random number generator from the respondent's lifetime traumas. Occurrence of the 17 DSM-IV criterion B-D PTSD symptoms was assessed for the month after each trauma when the respondent experienced the largest number of symptoms. (Respondents who reported only one lifetime trauma were, of course, assessed only once.) Respondents who reported any lifetime criterion B-D symptoms of PTSD associated with either the worst or random trauma were then asked if they had three or more such symptoms in the 12 months before interview associated with any lifetime trauma. Respondents who answered affirmatively were then evaluated for 12-month PTSD and asked which lifetime events caused these 12-month symptoms. Twelve-month PTSD was defined as meeting full lifetime DSMIV/CIDI criteria and continuing to have at least some symptoms in the 12 months before the interview.
PTSD age of onset (AOO) for respondents with one TE was defined as the age in which TE occurred. AOO was assessed using special probing techniques shown experimentally to improve recall accuracy.[23] We know the AOO of PTSD for respondents with one event of a particular type (e.g., if a respondent reported PTSD associated with a car accident and only had one car accident, the AOO would be the age of that one car accident). For multiple events of the same type, we have the AOO for the first event, but we do not know if the PTSD is related to that first event or to a subsequent event. To address this issue, we used regression-based imputation. Regression-based imputation was used rather than mean imputation or imputation of random values to provide an estimate that makes use of other patterns in the data. For respondents with one type of TE (e.g., car accident) but multiple instances of that TE, the AOO was imputed using a regression-based imputation that predicts an age based on the data as well as the respondent's sex and current age. If an age of event was imputed to an age less than the original first age that was given, the age was reset to the original age. For respondents with more than one type of event, the second lowest age was taken to be their AOO. If the respondent had less than two “known” ages, an age was imputed for each of their unknown events, using the same regression described above. Then, the second lowest age was taken from their ages of events. All ages were restricted to a minimum of 8. While we consider this combination of empirical and rational imputation strategies the most reasonable approach to deal with missing AOO data, we recognize that any imputation method will necessarily be imperfect and results regarding the effects of AOO should be interpreted with caution.
Role Functioning
Role functioning was assessed with the disorder-specific Sheehan Disability Scale (SDS)[24], which asks respondents to rate how much a given 12-month disorder interfered with their functioning in each of four role domains (home management, ability to work, social life, and close relationships) using a 0–10 response scale with labels of None (0), Mild (1–3), Moderate (4–6), Severe (7–9), and Very Severe interference. A global SDS score was also created by assigning each respondent the highest SDS domain score reported across the four domains.
ANALYSIS METHODS
The associations between number of associated TE types and other characteristics of 12-month PTSD related were examined using cross-tabulations and logistic regression analysis.[25] A hierarchy of logistic regression models was considered. The first model examined the association between number of associated TE types and severe functional impairment controlling for age, sex, country, AOO, and duration (defined as time since AOO) of the current episode of PTSD. The second model then added information about TE type and the third model added information about prior lifetime DSM-IV/CIDI disorders to determine whether these variables explained the observed association between number of associated TE types and the outcome.
Further analyses compared 12-month PTSD associated with 1–3 versus 4 or more event types in relation to demographic factors, AOO, duration, trauma types, comorbid mental disorders, and PTSD symptom clusters. The logistic regression coefficients and their standard errors were exponentiated and are reported here as odds ratios (ORs) with 95% confidence intervals. To adjust for the weighting and clustering of the WMH data, standard errors were estimated using the Taylor series method[26] implemented in the SUDAAN software system.[27] Multivariate significance was evaluated with Wald x2 tests based on design-corrected coefficient variance–covariance matrices. Statistical significance was consistently evaluated using .05 level two-sided tests.
RESULTS
PREVALENCE
Twelve-month prevalence (standard error) of DSMIV/CIDI PTSD in the total sample is 1.1% (see Table 1). The three highest country-specific prevalence estimates are in Northern Ireland (3.8%), the United States (2.5%), and New Zealand (2.1%), whereas the lowest are in Beijing and Shanghai in the PRC (0.2%), Colombia (0.3%), and Mexico (0.3%). Prevalence varies significantly across the total subsamples of respondents in low/lower-middle (0.8%), upper-middle (0.7%), and high (1.5%) income countries (, P < .001).
TABLE 1
Overall prevalence of 12-month DSM-IV/CIDI PTSD in each WMH survey
| % | (SE) | (n1)a | (n2)b | |
|---|---|---|---|---|
| Low/lower-middle income | ||||
| Colombia | 0.3 | (0.1) | (10) | (2,381) |
| People's Republic of China (Beijing, Shanghai) | 0.2 | (0.1) | (7) | (1,628) |
| Ukraine | 2.0 | (0.4) | (69) | (1,719) |
| Total lower-middle income | 0.8 | (0.2) | (86) | (5,728) |
| Upper-middle income | ||||
| Brazil (Sao Paulo) | 1.0 | (0.2) | (52) | (2,942) |
| Bulgaria | 0.9 | (0.2) | (35) | (2,233) |
| Lebanon | 1.6 | (0.6) | (22) | (1,031) |
| Mexico | 0.3 | (0.1) | (19) | (2,362) |
| Romania | 0.4 | (0.2) | (11) | (2,357) |
| South Africa | 0.4 | (0.1) | (21) | (4,315) |
| Total upper-middle income | 0.7 | (0.1) | (159) | (15,240) |
| High income | ||||
| Belgium | 0.6 | (0.1) | (16) | (1,043) |
| France | 1.4 | (0.3) | (33) | (1,436) |
| Germany | 0.5 | (0.2) | (19) | (1,323) |
| Italy | 0.4 | (0.1) | (17) | (1,779) |
| Israel | 0.4 | (0.1) | (15) | (4,859) |
| Japan | 0.4 | (0.2) | (9) | (1,682) |
| Netherlands | 1.2 | (0.3) | (31) | (1,094) |
| New Zealand | 2.1 | (0.2) | (304) | (7,312) |
| Northern Ireland | 3.8 | (0.5) | (96) | (1,986) |
| Spain | 0.4 | (0.1) | (29) | (2,121) |
| United States | 2.5 | (0.2) | (227) | (5,692) |
| Total high income | 1.5 | 0.1 | 797 | 30,327 |
| Total | 1.1 | (0.0) | (1,042) | (51,295) |
| Chi-square 2 df (difference between country groups) | 53.7* | |||
| Chi-square 19 df (difference between countries) | 354.6* |
DISTRIBUTION AND FUNCTIONAL IMPAIRMENT ASSOCIATED WITH NUMBER OF ASSOCIATED TE TYPES
Symptoms associated with more than one TE type have been reported by 19.8% of respondents with 12-month PTSD . Severe role impairment associated with PTSD in at least one of the four SDS role domains was reported by 42% of respondents with 12-month PTSD, including 23.2% who reported severe impairment in the domain of work, 24.2% in home maintenance, 26.8% in close relationships, and 28.9% in social life (see Table A3). Functional impairment in work (OR = 5.2), home maintenance (OR = 2.6), close relationships (OR = 7.6), social life (OR = 4.2), and overall (OR = 6.0) is elevated among respondents with 12-month PTSD associated with four or more TE types compared to respondents with 12-month PTSD associated with one TE type, controlling for sex, country, AOO, and duration. No significant differences in functional impairment are observed for respondents with 12-month PTSD associated with two or three versus one TE type. Odds of severe functional impairment in work (OR = 4.7), close relationships (OR = 7.4), and overall functioning (OR = 6.2) remain significantly elevated among respondents with 12-month PTSD associated with four or more TE types controlling for type of index TE and other 12-month mental disorders (detailed results of trauma type and comorbidity analysis are available on request).
The critical distinction observed in functional impairment was between cases related to four or more versus three or fewer TE types (see Table A3). Of note, 69% of respondents with 12-month PTSD reported four or more lifetime TE types, but only 4.8% (n 51) of such respondents reported their symptoms were associated with four or more TE types (see Table 2). For the remainder of this manuscript, we will refer to 12-month PTSD associated with four or more TE types as 4+/PTSD and 12-month PTSD associated with three or fewer TE types as 3−/PTSD.
TABLE 2
The associations (odds ratios) between number of TEs implicated in PTSD and severe functional impairment in four domains of role functioning among respondents with 12-month DSM-IV/CIDI PTSD based on three different models (n = 1,042)
| Predictors | ||||||
|---|---|---|---|---|---|---|
| Role domain/ number of TEs | Number of TEs | Number and type of TEs | Number and type of TEs and comorbidity | |||
| OR | (95% CI) | OR | (95% CI) | OR | (95% CI) | |
| I. Work | ||||||
| 2 TEs | 1.3 | (0.7-2.4) | 1.3 | (0.7-2.3) | 1.3 | (0.7-2.6) |
| 3 TEs | 1.4 | (0.6-3.7) | 1.3 | (0.5-2.9) | 1.2 | (0.5-2.8) |
| 4+ TEs | 5.2* | (2.3-11.4) | 5.1* | (1.6-15.8) | 4.7* | (1.4-16.0) |
| 17.4* | 8.3* | 6.8 | ||||
| II. Home maintenance | ||||||
| 2 TEs | 0.6 | (0.3-1.1) | 0.6 | (0.3-1.1) | 0.6 | (0.3-1.1) |
| 3 TEs | 0.7 | (0.2-1.9) | 0.6 | (0.2-1.7) | 0.6 | (0.2-1.9) |
| 4+ TEs | 2.6* | (1.2-5.7) | 1.8 | (0.6-5.7) | 1.8 | (0.5-5.8) |
| 9.6* | 6.1 | 4.4 | ||||
| III. Close relationships | ||||||
| 2 TEs | 1.0 | (0.6-1.9) | 0.9 | (0.4-1.7) | 0.8 | (0.4-1.8) |
| 3 TEs | 1.2 | (0.6-2.5) | 0.9 | (0.4-2.2) | 0.9 | (0.4-2.0) |
| 4+ TEs | 7.6* | (3.1-18.3) | 8.8* | (2.7-28.9) | 7.4* | (2.1-26.7) |
| 20.8* | 16.0* | 11.2* | ||||
| IV. Social life | ||||||
| 2 TEs | 1.0 | (0.5-1.2) | 1.0 | (0.5-1.7) | 1.0 | (0.5-1.9) |
| 3 TEs | 1.6 | (0.4-2.9) | 1.2 | (0.5-2.8) | 1.2 | (0.5-2.7) |
| 4+ TEs | 4.2* | (2.5-14.9) | 3.8* | (1.3-11.3) | 3.2 | (0.9-10.7) |
| 14.3* | 6.3 | 3.7 | ||||
| V. Global | ||||||
| 2 TEs | 0.7 | (0.5-1.2) | 0.7 | (0.4-1.2) | 0.6 | (0.3-1.2) |
| 3 TEs | 1.1 | (0.4-2.9) | 0.9 | (0.4-2.2) | 0.8 | (0.3-1.9) |
| 4+ TEs | 6.0* | (2.5-14.9) | 7.3* | (2.2-24.2) | 6.2* | (1.9-20.0) |
| 16.4* | 14.9* | 12.0* | ||||
Note: All models include controls for sex, country, age of onset, and duration (defined as time since age of onset). They are run on the subset of respondents with 12-month PTSD. Comorbidity is defined by dummies for other 12-month DSM-IV/CIDI disorders including MDE/dysthymia, bipolar, panic disorder or agoraphobia, GAD, adult separation anxiety social phobia, specific phobia, IED, conduct disorder, ODD, ADHD, alcohol abuse, alcohol dependence, drug abuse, drug dependence. Coefficients of disorders are not shown but available on request.
SOCIODEMOGRAPHIC CORRELATES
In multivariable models, odds of 4+/PTSD are significantly elevated among people who are not married or cohabitating (OR = 2.5) and not employed (OR = 2.5). Women have increased odds of 4+/PTSD (OR = 2.2, 95% CI 0.7–6.9), but the difference is not statistically significant. Education is unrelated to having 4+/PTSD.
TRAUMA TYPES
As one would expect, each of the 15 TE types considered here is more likely to be implicated in the cases of 4+/PTSD than 3−/PTSD. More interestingly, though, 9 of the 15 TE types have significantly higher on a proportional basis than among cases of 4+/PTSD than 3−/PTSD. Physical abuse in childhood, physical abuse by a spouse or partner, physical assault, sexual assault, automobile accidents, traumatic death of a loved one, other trauma to a loved one, witnessing family violence as a child, and witnessing a traumatic injury or death are all significantly more common among respondents with 4+/PTSD than 3-/PTSD.
Physical abuse −by a spouse or partner and physical assault comprise a larger proportion of all events for respondents with 4+/PTSD. In contrast, sudden unexpected death of a loved one and network events comprise a larger proportion of all events for respondents with 3−/PTSD (see Table 3).
TABLE 3
Distributions of types of TEs implicated in cases of DSM-IV/CIDI PTSD associated with 1-3 versus 4+ TEs
| % of people with each event among respondents with 3-/PTSD | % of people with each event among respondents with with 4+/PTSD | % of events among respondents with 3-/PTSD | % of events among respondents with 4+/PTSD | |||||
|---|---|---|---|---|---|---|---|---|
| % | (SE) | % | (SE) | % | (SE) | % | (SE) | |
| I. War related | ||||||||
| Combat experience | 0.8 | (0.3) | 6.0 | (4.7) | 0.6 | (0.3) | 1.1 | (0.8) |
| Other war experience | 2.5 | (0.9) | 16.8 | (6.7) | 2.0 | (0.8) | 3.0 | (1.2) |
| II. Physical violence | ||||||||
| Physically abused as a child | 5.6* | (0.9) | 44.0 | (8.3) | 4.6 | (0.8) | 7.9 | (1.6) |
| Physically abused by spouse/partner | 5.6* | (0.8) | 56.2 | (8.2) | 4.6* | (0.7) | 10.1 | (1.4) |
| Physically assaulted or threatened | 9.0* | (1.0) | 67.5 | (7.9) | 7.3* | (0.8) | 12.1 | (1.4) |
| III. Sexual violence | ||||||||
| Sexually assaulted | 13.5* | (1.2) | 78.4 | (6.6) | 11.1 | (1.0) | 14.1 | (1.3) |
| IV. Accidents | ||||||||
| Automobile accident | 6.7* | (1.2) | 28.7 | (7.4) | 5.5 | (1.0) | 5.2 | (1.2) |
| Other life-threatening accident | 3.9 | (0.8) | 11.6 | (4.0) | 3.2 | (0.7) | 2.1 | (0.7) |
| Natural disaster | 0.7 | (0.3) | 9.2 | (4.4) | 0.6 | (0.2) | 1.7 | (0.8) |
| Life-threatening illness | 8.5 | (1.2) | 21.9 | (7.4) | 7.0 | (1.0) | 4.0 | (1.3) |
| V. Death | ||||||||
| Traumatic death of a loved one | 31.6* | (2.2) | 68.4 | (8.5) | 25.9* | (1.8) | 12.3 | (1.6) |
| VI. Network/witnessing | ||||||||
| Other TE to a loved one | 15.1* | (1.9) | 39.1 | (7.4) | 12.4* | (1.5) | 7.0 | (1.3) |
| Witnessed family violence as a child | 1.3* | (0.4) | 41.8 | (8.1) | 1.1* | (0.3) | 7.5 | (1.4) |
| Witnessed a traumatic injury or death | 3.8* | (0.8) | 35.6 | (8.0) | 3.1* | (0.6) | 6.4 | (1.3) |
| VII. Other | ||||||||
| Other | 13.6 | (1.6) | 30.7 | (7.9) | 11.2* | (1.2) | 5.5 | (1.3) |
| (n) | (991) | (51) | (991) | (51) | ||||
AOO AND DURATION OF PTSD
Respondents with 4 /PTSD have a significantly younger AOO and longer duration controlling for demographic factors (detailed results of the models are available on request). This substantially younger AOO for 4+/PTSD is illustrated by the cumulative probability curve shown in Fig. 1.
Cumulative probability of 4+/PTSD versus 3-/PTSD by age of onset in the World Mental Health Surveys.
The median AOO is 11 for 4+/PTSD versus 29 for 3−/PTSD. The mean AOO of 4+/PTSD is significantly younger [Mean = 16.2 (SE = 1.5)] compared to that for 3−/PTSD [Mean = 31.7 (SE = 0.7); x2 = 45.59, P < .00001).
The duration of 4+/PTSD is also significantly longer than that related to 3−/PTSD. The median duration is 263 months for 4+/PTSD versus 93 for 3-/PTSD. The mean duration of 4+/PTSD is significantly longer [Mean = 284.0 (SE = 25.7)] compared to that for 3−/PTSD [Mean 147.1 (SE = 5.4); x2 45.59, P < .00001).
OTHER 12-MONTH DSM-IV/CIDI MENTAL DISORDERS
Five of 15 individual 12-month mental disorders are more common among respondents with 4 /PTSD, controlling for age, sex, and country. Elevated+odds of bipolar disorder (OR = 2.6), GAD (OR = 2.9), adult separation anxiety (OR = 3.6), social phobia (OR = 2.4), and specific phobia (OR = 2.1) are observed for 4+/PTSD. Prevalence of MDD/dysthymia, IED, ODD, ADHD, and alcohol abuse and dependence is higher for respondents with 4+/PTSD. However, these differences are not statistically significant. Prevalence of conduct disorder, drug abuse, and drug dependence is higher among respondents with 3−/PTSD, but the differences are not statistically significant (see Table 4).
TABLE 4
Odds ratios for association between 12-month DSM-V/CIDI disorders and PTSD associated with 1-3 events versus 4+ events (n = 1,042)
| % of respondents with each disorder among 3-/PTSD | % of respondents with each disorder among 4+/PTSD | Respondents with 4+ events versus those with 1-3 events | ||||
|---|---|---|---|---|---|---|
| % | (SE) | % | (SE) | ORa | (95% CI) | |
| I. Mood disorders | ||||||
| MDE/dysthymia | 40.9 | (2.1) | 60.8 | (8.5) | 2.1 | (1.0-4.7) |
| Bipolar | 8.2 | (1.0) | 26.2 | (7.2) | 2.6* | (1.1-6.2) |
| Any mood | 42.6 | (2.1) | 68.8 | (8.3) | 2.7* | (1.2-6.3) |
| II. Anxiety disorders | ||||||
| Panic disorder or agoraphobia | 15.5 | (1.4) | 32.1 | (7.9) | 2.0 | (0.9-4.2) |
| GAD | 18.2 | (1.4) | 42.7 | (8.9) | 2.9* | (1.4-5.9) |
| Adult separation anxiety | 3.8 | (0.5) | 16.6 | (6) | 3.6* | (1.4-9.3) |
| Social phobia | 17.5 | (1.3) | 41.7 | (8.1) | 2.4* | (1.3-4.7) |
| Specific phobia | 25 | (1.7) | 49.9 | (8.6) | 2.1* | (1.1-4.1) |
| Any anxiety | 46.2 | (2.1) | 85.8 | (5.6) | 5.2* | (2.2-12.5) |
| III. Disruptive behavior disorders | ||||||
| IED | 5.6 | (0.8) | 14.1 | (5.9) | 2.3 | (0.7-7.8) |
| Conduct disorderb | 2.3 | (0.9) | 1.2 | (1.2) | 0.5 | (0.1-4.0) |
| ODDb | 4.0 | (0.9) | 4.3 | (3.1) | 0.6 | (0.1-3.4) |
| ADHDb | 6.5 | (1.6) | 18.3 | (8.6) | 3.6 | (0.7-17.9) |
| Any impulse | 14.5 | (2.1) | 18.3 | (8.6) | 1.1 | (0.3-4.8) |
| IV. Substance disorders | ||||||
| Alcohol abuse | 6.3 | (1.0) | 11.2 | (4.9) | 1.7 | (0.6-5.0) |
| Alcohol dependence | 5 | (0.8) | 10.3 | (4.8) | 2.4 | (0.8-6.9) |
| Drug abuse | 2.3 | (0.5) | 1.7 | (1.7) | 0.7 | (0.1-5.6) |
| Drug dependence | 1.9 | (0.5) | 1.7 | (1.7) | 0.8 | (0.1-6.3) |
| Any substance | 7.7 | (1.1) | 14.1 | (5.3) | 1.8 | (0.7-4.9) |
| Chi-square 15 df (significance of all ORs) | 69.2* | (< 0.001) | ||||
| Chi-square 14 df (significant difference between ORs) | 23.2 | (0.06) | ||||
PTSD SYMPTOM PROFILES
The mean number of total lifetime PTSD symptoms is significantly higher for respondents with 4+/PTSD. This difference is driven by significantly higher symptoms in the hyperarousal cluster; one standard deviation increase in hyperarousal symptoms is associated with elevated odds (OR = 1.4) of 4+/PTSD (see Table 5).
TABLE 5
Odds ratios predicting 12-month 4+/PTSD: multivariate symptom profile associations (no controls)
| 3-/PTSD | 4+/PTSD | |||||
|---|---|---|---|---|---|---|
| Mean | (SE) | Mean | (SE) | OR | (95% CI) | |
| Symptom counts | ||||||
| Re-experiencing | −0.01 | (0.04) | 0.34 | (0.18) | 1.1 | (0.8-1.5) |
| Avoidance | 0.0 | (0.04) | −0.16 | (0.18) | 0.9 | (0.7-1.1) |
| Numbing | −0.02 | (0.05) | 0.47 | (0.18) | 1.3 | (0.9-1.8) |
| Hyperarousal | −0.02 | (0.05) | 0.61 | (0.14) | 1.5* | (1.1-2.1) |
| Total | −0.02 | (0.05) | 0.52 | (0.19) | 1.4* | (1.1-1.9) |
| 2.4* (0.050) | ||||||
| 2.7* (0.047) | ||||||
Note: Means are expressed in standard deviation units.
DISCUSSION
Interpretation of these results is subject to several study limitations. The first limitation is that the number of respondents with 4+/PTSD was too small for country-specific analyses. The total number of respondents with 12-month PTSD across all surveys was only 1,042, with 3.3% reporting 4+/PTSD. Although larger than most treatment-seeking samples, the small number of respondents with 4+/PTSD limited power to detect effects and led to large standard errors in some cases. Another limitation is that lifetime PTSD was asked in relation to an index trauma. This may be problematic, especially in the setting of multiple traumas and a disorder characterized by re-experiencing and avoidance of symptoms. In fact, majority of respondents exposed to at least one TE are exposed to multiple TEs[1,4] and the prevalence of PTSD is increased when the disorder is assessed in relation to all TEs,[28] suggesting some respondents with PTSD may have been classified as non-cases. A third limitation is data were available only for the number of different types of TEs associated with 12-month PTSD. Debate exists as to whether PTSD related to chronic exposure to a TE, such as often occurs with partner violence or childhood abuse, is more “complex” than from PTSD related to a single incident TE.[5,7,29] The results presented here do not speak directly to this debate. A fourth limitation is that although existing evidence supports the cross-national validity of the CIDI, its reliability and validity have not yet been established for all translated versions used here. A fifth limitation is the results presented here apply specifically to 12-month PTSD. Findings related to 12-month PTSD may not be representative of all PTSD cases. Prevalent cases of PTSD are more likely to be chronic and will not include cases of lifetime PTSD who recovered from the disorder. It is possible that the findings observed here are more characteristic of chronic PTSD than of PTSD that re mits. Further research is needed to examine whether the relation of multiple events to 12-month PTSD observed here generalizes to lifetime PTSD. A sixth limitation is that pretrauma vulnerability factors may contribute to differences observed between 4+ and 3-/PTSD and were not examined here. Finally, the WMH research design is cross-sectional, limiting conclusions about the complex causal pathways between PTSD, psychopathology, and functional impairment.
Notwithstanding the above limitations, these WMH results offer the first cross-national population-based epidemiological data on the prevalence of 12-month PTSD across high-, middle-, and low-income countries. The prevalence of 12-month PTSD varies significantly from a high of 3.8% in Northern Ireland to a low of 0.2% in China. These are also the first cross-national epidemiologic data of which we are aware on the differential correlates of 12-month PTSD associated with 4+/PTSD versus 3-/PTSD.
Four findings are noteworthy. First, although the majority of 12-month PTSD cases reported experiencing four or more TE types over their life course, only about 19% associated their 12-month PTSD with more than one TE type. Although prior epidemiologic studies have shown that exposure to multiple TEs is associated with increased risk of PTSD,[2,30–32] this is the first epidemiologic study of which we are aware that has reported on the proportion of PTSD cases who associate their disorder with multiple versus single event types. Further research is needed to understand why some respondents with multiple TEs attribute their PTSD to multiple event types and others, with similar levels of TEs, do not. For example, persons with PTSD may be more likely to attribute the disorder to multiple event types if their intrusive memories are about multiple event types. We were unable to test this hypothesis in our data. Moreover, the question of how such attributions contribute to differences in functioning among persons with PTSD also merits investigation.
Second, 4+/PTSD is associated with more severe functional impairment across all domains than 3−/PTSD. This suggests the presence of a risk threshold of four or more event types beyond which the impact of trauma on functioning worsens. An intriguing WMH finding is that more severe functional impairment in work and close relationship domains observed in respondents with 4+/PTSD is not explained by differences in TE types or comorbid disorders. Future research on epidemiologic studies should collect the data necessary to examine alternative hypotheses for why persons with 4+/PTSD have more severe functional impairment.
Third, the types of TEs associated with 4+/PTSD versus 3-/PTSD differed. Unsurprisingly, respondents with 4+/PTSD had higher rates for a range of TEs. However, witnessing parental violence, physical abuse by a spouse or partner, and other physical assault comprised a significantly higher proportion of TEs among 4+/PTSD. Unexpected death of a close friend or relative and network events comprised a higher proportion of TEs for 3-/PTSD. Because type of event, particularly interpersonal violence, tracked closely with number of TEs, we cannot determine from our data whether there are differences among those with 4+/PTSD according to trauma type. However, it is noteworthy that the 4+/PTSD was associated with greater proportion of physical violence events. Physical and sexual assault in childhood and adolescence are risk factors for revictimization, including partner violence, in adulthood.[33,34] Revictimization may lead some persons to be exposed to multiple types of violence and contribute to the higher proportion of these events among respondents with 4+/PTSD.
Finally, 4+/PTSD had an earlier AOO, longer duration, higher comorbidity with mood and anxiety disorders, and elevated hyperarousal symptoms. These data are consistent with research in clinical samples that suggest exposure to cumulative trauma is associated with a more “complex” presentation of PTSD.[5,7,35] They are also consistent with our previous report that number and type of trauma was associated with a dissociative subtype of PTSD.[36] However, the proposed diagnosis of “complex PTSD” includes characteristics such as emotion regulation deficits, identity disturbances, and interpersonal problems not systematically assessed in the WHO DSM-IV/CIDI, leaving it for future investigators to investigate the relation between multiple TEs and complex PTSD in epidemiologic samples.
Our data on 12-month PTSD provide a snapshot of the public health burden of PTSD in over 20 countries. Over 1% of the population of these countries suffers from PTSD in a 12-month period, highlighting that PTSD is a global public health problem meriting international attention. Among persons with 12-month PTSD, 4+/PTSD cases reported greater functional impairment and morbidity. These findings have three practical implications. First, among person with 12-month PTSD, 4+/PTSD cases are in greatest need and may require disproportionate resources from the healthcare system. Second, treatment providers should assess whether persons presenting with PTSD attribute their diagnosis to multiple events. Such attri bution may be a marker of a more complicated clinical presentation that merits attention.
Third, clinical research is needed to determine whether patients with 4+/PTSD require different or additional intervention strategies from persons who attribute their PTSD to fewer events. Trauma-focused cognitive-behavioral therapies, including prolonged exposure[37,38] and cognitive processing therapy[39], are effective for approximately 70% of persons with PTSD. Recently published expert consensus treatment guidelines for “complex PTSD” indicate that many practitioners believe patients with PTSD related to multiple and particularly chronic trauma exposure require therapy that includes skills training in areas such as interpersonal relationships and emotion regulation in order to effectively engage in trauma-focused work.[7] Finally, when considering the Dissociative Subtype of PTSD, which is associated with a greater number of TEs, it has also been shown that, in comparison with individuals with PTSD alone, those with PTSD and dissociative symptoms benefit more from different therapeutic approaches.[40] Specifically, individuals with the DSM-5 Dissociative Subtype exhibit great therapeutic outcomes when prolonged exposure therapy is augmented by a course of skills training in affective and interpersonal regulation (STAIR)[41] and from cognitive processing therapy that includes both exposure and cognitive components, in contrast to patients with low levels of dissociation who do better with cognitive therapy, alone.[42] Further research is needed to determine whether persons with 4+/PTSD are less responsive to treatment or if such guidelines apply to the subset of PTSD cases identified here.
Acknowledgments
The World Health Organization World Mental Health (WMH) Survey Initiative was supported by the National Institute of Mental Health (NIMH; R01 MH070884), the John D. and Catherine T. MacArthur Foundation, the Pfizer Foundation, the US Public Health Service (R13-MH066849, R01-MH069864, R01 DA016558, and R01-MH093612), the Fogarty International Center (FIRCA R03-TW006481), the Pan American Health Organization, Eli Lilly and Company, Ortho-McNeil Pharmaceutical, GlaxoSmithKline, and Bristol-Myers Squibb. We thank the staff of the WMH Data Collection and Data Analysis Coordination Centres for assistance with instrumentation, fieldwork, and consultation on data analysis. None of the funders had any role in the design, analysis, interpretation of results, or preparation of this paper. A complete list of all within-country and cross-national WMH publications can be found at http://www.hcp.med.harvard.edu/wmh/. The São Paulo Megacity Mental Health Survey is supported by the State of São Paulo Research Foundation (FAPESP) Thematic Project Grant 03/00204–3. The Bulgarian Epidemiological Study of common mental disorders EPIBUL is supported by the Ministry of Health and the National Center for Public Health Protection. The Beijing, People's Republic of China World Mental Health Survey Initiative is supported by the Pfizer Foundation. The Colombian National Study of Mental Health (NSMH) is supported by the Ministry of Social Protection. The ESEMeD project is funded by the European Commission (Contracts QLG5-1999-01042; SANCO 2004123), the Piedmont Region (Italy), Fondo de Investigacion Sanitaria, Instituto de Salud Carlos III, Spain (FIS 00/0028), Ministerio de Ciencia y Tecnología, Spain (SAF 2000-158-CE), Departament de Salut, Generalitat de Catalunya, Spain, Instituto de Salud Carlos III (CIBER CB06/02/0046, RETICS RD06/0011 REM-TAP), and other local agencies and by an unrestricted educational grant from GlaxoSmithKline. The Israel National Health Survey is funded by the Ministry of Health with support from the Israel National Institute for Health Policy and Health Services Research and the National Insurance Institute of Israel. The World Mental Health Japan (WMHJ) Survey is supported by the Grant for Research on Psychiatric and Neurological Diseases and Mental Health (H13-SHOGAI-023, H14-TOKUBETSU-026, H16-KOKORO-013) from the Japan Ministry of Health, Labour and Welfare. The Lebanese National Mental Health Survey (LEBANON) is supported by the Lebanese Ministry of Public Health, the WHO (Lebanon), National Institute of Health/Fogarty International Center (R03 TW006481-01), Sheikh Hamdan Bin Rashid Al Maktoum Award for Medical Sciences, anonymous private donations to IDRAAC, Lebanon, and unrestricted grants from AstraZeneca, Eli Lilly, GlaxoSmithKline, Hikma Pharm, Janssen Cilag, Pfizer, Roche, Sanofi-Aventis, Servier, and Novartis. The Mexican National Comorbidity Survey (MNCS) is supported by The National Institute of Psychiatry Ramon de la Fuente (INPRFMDIES 4280) and by the National Council on Science and Technology (CONACyTG30544-H), with supplemental support from the PanAmerican Health Organization (PAHO). Te Rau Hinengaro: The New Zealand Mental Health Survey (NZMHS) is supported by the New Zealand Ministry of Health, Alcohol Advisory Council, and the Health Research Council. The Northern Ireland Study of Mental Health was funded by the Health & Social Care Research & Development Division of the Public Health Agency. The Romania WMH study projects “Policies in Mental Health Area” and “National Study regarding Mental Health and Services Use” were carried out by National School of Public Health & Health Services Management (former National Institute for Research & Development in Health), with technical support of Metro Media Transilvania, the National Institute of Statistics-National Centre for Training in Statistics, SC. Cheyenne Services SRL, Statistics Netherlands and were funded by Ministry of Public Health (former Ministry of Health) with supplemental support of Eli Lilly Romania SRL. The South Africa Stress and Health Study (SASH) is supported by the US National Institute of Mental Health (R01-MH059575) and National Institute of Drug Abuse with supplemental funding from the South African Department of Health and the University of Michigan. The Ukraine Comorbid Mental Disorders during Periods of Social Disruption (CMDPSD) study is funded by the US National Institute of Mental Health (RO1-MH61905). The US National Comorbidity Survey Replication (NCS-R) is supported by the National Institute of Mental Health (U01-MH60220) with supplemental support from the National Institute of Drug Abuse (NIDA), the Substance Abuse and Mental Health Services Administration (SAMHSA), the Robert Wood Johnson Foundation (RWJF; Grant 044708), and the John W. Alden Trust. These surveys were carried out in conjunction with the World Health Organization WMH Survey Initiative. We thank the WMH staff for assistance with instrumentation, fieldwork, and data analysis. A complete list of WMH publications can be found at www.hcp.med.harvard.edu/wmh
Financial disclosure
Dr. Kessler has been a consultant for Analysis Group, GlaxoSmithK-line Inc., Kaiser Permanente, Merck & Co, Inc., Ortho-McNeil Janssen Scientific Affairs, Pfizer Inc., Sanofi-Aventis Groupe, Shire US Inc., SRA International, Inc., Takeda Global Research & Development, Transcept Pharmaceuticals Inc., Wellness and Prevention, Inc., and Wyeth-Ayerst; has served on advisory boards for Eli Lilly & Company, Mindsite, and Wyeth-Ayerst; and has had research support for his epidemiological studies from Analysis Group Inc., Bristol-Myers Squibb, Eli Lilly & Company, EPI-Q, Ortho-McNeil Janssen Scientific Affairs., Pfizer Inc., Sanofi-Aventis Groupe, and Shire US, Inc. He owns stock in Datastat, Inc. Dr. Demyttenaere has served on advisory boards for, speaker bureaus for, and has research grants from Astra Zeneca, Eli Lilly, GSK, Lundbeck, Takeda, Servier. Dr. Haro has been a consultant and served on speaker bureaus for Eli Lilly and Co., has board memberships at Lundbeck and Roche, and has had research support from GlaxoSmithKline. Dr. Kawakami has been a part-time physician at the Riken Institute, a consultant for Junpukai Foundation and the Sekisui Corporation, has served on speaker bureaus for GlaxoSmithKline, Ezai, and Pfizer, received royalties from Fujitsu Software Technologies, Ltd., Chuo-Hoki-Shuppan, Igaku-Shoin, Kyobundo, Life Science, Maruzen, Nanko-do, and Nanzan-do, and has received research support from Fujitsu Software Technologies, Ltd. Dr. Stein has been a consultant for Servier and Biocodex.
APPENDIX
TABLE A1
WMH sample characteristics by World Bank income categoriesa
| Country by income category | Surveyb | Sample characteristicsc | Field dates | Age range | Sample size | Responsed rated | |
|---|---|---|---|---|---|---|---|
| Part 1 | Part 2 | ||||||
| I. Low- and lower-middle income countries | |||||||
| Colombia | NSMH | All urban areas of the country (approximately 73% of the total national population). | 2003 | 18-65 | 4,426 | 2,381 | 87.7 |
| PRCe-Beijing/Shanghai | B-WMH S-WMH | Beijing and Shanghai metropolitan areas. | 2002-3 | 18-70 | 5,201 | 1,628 | 74.7 |
| Ukrainef | CMDPSD | Nationally representative. | 2002 | 18-91 | 4,724 | 1,719 | 78.3 |
| Total | 14,351 | 5,728 | |||||
| II. Upper-middle income countries | |||||||
| Brazil São Paulo | São Paulo Megacity | São Paulo metropolitan area. | 2005-7 | 18-93 | 5,037 | 2,942 | 81.3 |
| Bulgaria | NSHS | Nationally representative. | 2003-7 | 18-98 | 5,318 | 2,233 | 72.0 |
| Lebanon | LEBANON | Nationally representative. | 2002-3 | 18-94 | 2,857 | 1,031 | 70.0 |
| Mexico | M-NCS | All urban areas of the country (approximately 75% of the total national population). | 2001-2 | 18-65 | 5,782 | 2,362 | 76.6 |
| Romania | RMHS | Nationally representative. | 2005-6 | 18-96 | 2,357 | 2,357 | 70.9 |
| South Africaf | SASH | Nationally representative. | 2003-4 | 18-92 | 4,315 | 4,315 | 87.1 |
| Total | 25,666 | 15,240 | |||||
| III. High-income countries | |||||||
| Belgium | ESEMeD | Nationally representative. The sample was selected from a national register of Belgium residents | 2001-2 | 18-95 | 2,419 | 1,043 | 50.6 |
| France | ESEMeD | Nationally representative. The sample was selected from a national list of households with listed telephone numbers. | 2001-2 | 18-97 | 2,894 | 1,436 | 45.9 |
| Germany | ESEMeD | Nationally representative. | 2002-3 | 18-95 | 3,555 | 1,323 | 57.8 |
| Israel | NHS | Nationally representative. | 2002-4 | 21-98 | 4,859 | 4,859 | 72.6 |
| Italy | ESEMeD | Nationally representative. The sample was selected from municipality resident registries. | 2001-2 | 18-100 | 4,712 | 1,779 | 71.3 |
| Japan | WMHJ2002-2006 | Eleven metropolitan areas. | 2002-6 | 20-98 | 4,129 | 1,682 | 55.1 |
| Netherlands | ESEMeD | Nationally representative. The sample was selected from municipal postal registries. | 2002-3 | 18-95 | 2,372 | 1,094 | 56.4 |
| New Zealandf | NZMHS | Nationally representative. | 2003-4 | 18-98 | 12,790 | 7,312 | 73.3 |
| Northern Ireland | NISHS | Nationally representative. | 2004-7 | 18-97 | 4,340 | 1,986 | 68.4 |
| Spain | ESEMeD | Nationally representative. | 2001-2 | 18-98 | 5,473 | 2,121 | 78.6 |
| United States | NCS-R | Nationally representative. | 2002-3 | 18-99 | 9,282 | 5,692 | 70.9 |
| Total | 56,825 | 30,327 | |||||
| IV. Total | 96,842 | 51,295 | 70.4 | ||||
TABLE A2
Original 29 events clustered into 15 events and seven groups
| New 15 events (grouped into seven groups) | Original 29 events |
|---|---|
| I. War related | |
| Combat experience | Combat experience, purposely injured, tortured, or killed someone |
| Other war experience | Relief worker in war zone, civilian in war zone, civilian in region of terror, refugee, saw atrocities |
| II. Physical violence | |
| Physically abused as a child | Beaten up by caregiver |
| Physically abused by spouse/partner | Beaten up by spouse or romantic partner |
| Physically assaulted or threatened | Kidnapped, beaten up by someone, mugged or threatened with a weapon, stalked |
| III. Sexual violence | |
| Sexually assaulted | Raped, sexually assaulted |
| IV. Accidents | |
| Automobile accident | Automobile accident |
| Other life-threatening accident | Toxic chemical exposure, other life-threatening accident, man-made disaster, accidentally caused serious injury or death |
| Natural disaster | Natural disaster |
| Life-threatening illness | Life-threatening illness |
| V. Death | |
| Traumatic death of a loved one | Unexpected death of a loved one |
| VI. Network/witnessing | |
| Other PLE to a loved one | Child with serious illness, traumatic event to a loved one |
| Witnessed family violence as a child | Witnessed family fight at home |
| Witnessed a traumatic injury or death | Witnessed death or dead body or saw someone seriously hurt |
| VII. Other | |
| Other | Other event, private event |
TABLE A3
Functional impairment and 12-month PTSD associated with four or more versus three or fewer events
| Total | 3-/PTSD | 4+/PTSD | ||||||
|---|---|---|---|---|---|---|---|---|
| Severe impairmenta | Severe (%) | (SE) | Severe (%) | (SE) | Severe (%) | (SE) | Chi-square statisticb | P-value |
| Work | 23.20 | (2.0) | 22.12 | (1.83) | 54.78 | (8.58) | 13.79 | .0002 |
| Home | 24.18 | (2.0) | 23.50 | (1.76) | 44.10 | (8.56) | 5.83 | .0158 |
| Close relationships | 26.80 | (2.0) | 25.14 | (1.95) | 75.20 | (7.78) | 22.16 | .0000 |
| Social life | 28.91 | (2.0) | 27.74 | (2.06) | 63.21 | (8.78) | 12.93 | .0003 |
| Global | 41.95 | (2.0) | 40.63 | (2.13) | 80.67 | (6.80) | 13.97 | .0002 |
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