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Existing Sources of
Epidemiological Data on Trauma
Dean G. Kilpatrick Ph.D. and John Boyle Ph.D.
Medical U. of South Carolina ICF International
Workshop on Integrating New Measures of Trauma
into SAMSHA’s Data Collection Systems, 12/17/2015
Overview of Presentation
Key definitional and methodological issues important for
understanding epidemiological research on exposure to
potentially traumatic events (PTEs) and PTSD.
Review of three major national epidemiological studies that
produced prevalence estimates of PTE exposure and PTSD
among probability samples of adults including the NCS-R, the
National Survey on Alcohol and Related Disorders, and the 2008-
2012 National Survey on Drug Use and Health (NSDUH) Mental
Health Surveillance Study (MHSS).
Limitations of existing data from these studies to produce up-to-
date national and state level PTE and PTSD prevalence estimates
using DSM-5 criteria.
Overview (Continued)
Description of recently completed national study of PTE
and PTSD prevalence that demonstrates the feasibility of
collecting PTE and PTSD prevalence data using web-
based data collection.
Suggestions for how to integrate new measures of PTE
exposure and PTSD prevalence into SAMHSA’s data
collection programs and generate national and state-level
PTE and PTSD prevalence estimates using DSM-5 criteria.
What Does Trauma Mean?
Trauma has been used in two ways, sometimes as a STIMULUS
(e.g. a stressor event thought to be capable of having negative
effects on mental health and behavior)and sometimes as a
RESPONSE (e.g. responses of PTSD or related disorders that
occur following exposure to these stressor events).
When we say “new measures of trauma”, do we mean new
measures of exposure to stressor events, new measures of
responses following exposure to those stressor events, or both?
Importance of Stressor Events in the PTSD Diagnosis
PTSD Criterion A defines types of stressor events capable of
producing PTSD. If a stressor is not a Criterion A event, it
cannot, by definition, produce PTSD, so other PTSD criteria are
not assessed.
Many researchers call Criterion A events Traumatic Events
(TEs) or Potentially Traumatic Events (PTEs). PTE is a better
term because not everyone exposed develops PTSD, so events
are only potentially traumatic.
PTSD Criterion A definitions of PTEs differ in the DSM-III,
DSM-III-R, DSM-IV, and DSM-5, making it difficult to
compare PTE exposure or PTSD prevalence in studies
measuring PTEs or PTSD symptoms using different DSMs.
Key Methodological Issues for Measuring PTE and PTSD Prevalence
A challenge for epidemiological studies is to collect data in the
most cost effective way using methods that facilitate willingness
to disclose information about exposure to all relevant PTEs
including those involving sensitive topics.
A critical issue is whether the survey measures all relevant PTEs
using sensitive behaviorally specific questions to assess PTEs
with the highest probabilities of increasing risk of PTSD (e.g.
PTEs involving sexual violence, other interpersonal violence,
and military combat). If not, these PTEs are undetected, and
PTSD prevalence cannot be assessed properly.
Another challenge is measuring PTSD using current DSM PTSD
criteria that are capable of producing adequate estimates of
Partial, Subthreshold, or Subclinical PTSD.
Measuring Sexual Violence and Other Interpersonal Violence PTE Exposure
PTEs involving sexual violence, intimate partner violence, and
other interpersonal violence are often defined stereotypically by
respondents; they are extremely prevalent and stigmatizing, and
they are more difficult to measure than other PTEs.
Well-designed studies (e.g. CDC National Intimate Partner and
Sexual Violence Survey) indicate that 18% of adult women and
1.4% of adult men in the US have been victims of rape and that
35.6% of women and 28.5% of men have been victims of rape,
physical violence, or stalking by an intimate partner.
Research documents that you can’t measure these PTEs
properly with simple gatekeeping Qs; you need behaviorally
specific Qs that get around stereotypes.
Four Steps in Responding to Survey Questions
Comprehending the question and instructions
Retrieving specific memories or information relevant to the
question
Making judgments about whether the specific memories or
information match what is being asked in the question
Formulating a response based on whether the response is
accurate and other factors including concerns about stigma or
confidentiality
Source: Tourangeau, 1984; NRC Report on Estimating the
Incidence of Rape and Sexual Assault, 2014.
Three Major Studies Producing National PTE and PTSD Estimates
National Comorbidity Survey-Replication (NCS-R)
National Epidemiological Survey on Alcohol and Related
Conditions (NESARC)
National Survey on Drug Use and Health (NSDUH)
Mental Health Surveillance Study (MHSS)
NCS-Replication (NCS-R):
Conducted in early 2000s as a follow-up to original NCS
which was conducted in early 1990s.
National probability sample of English-speaking adults age
18 and older (N=5692) in the coterminous U.S.
Data on DSM-IV diagnoses were collected in face-to-face
interviews using the WHO-CIDI, a fully-structured interview
conducted by lay interviewers.
Lifetime PTE exposure was assessed comprehensively with a
series of 26 Qs about exposure to specific DSM-IV Criterion
A1 PTEs as well as follow-up Qs to find out which A1 PTE’s
also met A2 by resulting in the respondent having been
terrified or frightened, helpless, shocked or horrified, or
numb.
NCS-R PTE and PTSD Prevalence Findings
79.4% of the NCS-R sample had been exposed to one or
more DSM-III-defined PTE.
Lifetime PTSD prevalence using DSM-IV criteria was 6.8%
overall; 9.7% among women and 3.6% among men.
Past 12 months PTSD prevalence was 3.5% overall; 5.2%
among women and 1.8% among men.
National Epidemiological Survey on Alcohol and Related Conditions
NESARC study conducted in 2004-05 measured Full and
Partial PTSD in a nationally representative household
probability sample of 34,653 U.S. adults using the AUDADIS-
IV fully-structured interview.
Conducted by lay interviewers in person.
Assessed lifetime PTE exposure and PTSD using DSM-IV
criteria.
PTE exposure assessed with 27 Qs enumerating specific
PTEs falling under the DSM-IV definition. If they had more
than one PTSD, they identified the one that was the worst
The PTSD module measured all PTSD symptoms with no
skip outs and also measured functional impairment.
NESARC PTE and PTSD Prevalence Findings
79.7% of respondents were exposed to at least one PTE.
Lifetime prevalence of PTSD to the only or worst PTE was
6.4%.
Partial PTSD was defined as not meeting full diagnostic
criteria for PTSD but having at least one symptom in each
of the B, C, and D Criteria. Lifetime prevalence of Partial
PTSD was 6.6%.
Respondents with both Full PTSD and Partial PTSD had
elevated rates of lifetime mood, anxiety, substance use
disorders, and suicide attempts.
2008-12 NSDUH Mental Health Surveillance Study: Methodology
Subset of English-speaking adults 18 and older who
completed the NSDUH in person survey were recruited for
the MHSS (N=5652), which assessed selected mental
disorders using DSM-IV criteria.
Mental health professionals conducted survey via telephone
and assessed for mental disorders using modified version
of the SCID-I, a semi-structured interview.
MHSS PTE and PTSD Assessment
PTE exposure and PTSD assessed using DSM-IV criteria.
Lifetime exposure to PTEs measured using three stage
process. In Stage 1, respondents were asked two
gatekeeping screening questions about exposure to DSM-
IV Criterion A1 events. Stage 2 asked if they ever had re-
experiencing symptoms to any events. Stage 3 determine if
events met the A2 requirement that the event produced
“fear, helplessness, or horror”.
PTSD was assessed to the PTE they considered to have
affected them the most.
MHSS PTE Screening Questions
“Sometimes things happen to people that are extremely
upsetting- things like being in a life-threatening situation like a
disaster, very serious accident or fire; being physically assaulted
or raped; seeing another person killed or dead, or badly hurt; or
hearing about something horrible that happened to someone you
are close to. At anytime during your life, have any of these things
happened to you”?
If no:
“Have you ever been in any serious car accidents or have you
been victim of a crime”?
If no to both: skip out of PTSD module
MHSS PTSD Symptom Assessment
PTSD symptom assessment module had numerous skip outs:
If less than 1 Criterion B re-experiencing symptom, skip
out.
If less than 3 Criterion C avoidance/numbing systems, skip
out.
If less than 2 Criterion D hyperarousal symptoms, skip out.
MHSS Definition of Clinical PTSD and Subclinical PTSD
Clinical PTSD: cases that met all DSM-IV diagnostic criteria
for PTSD.
Definition of Subclinical PTSD includes: 1) cases that did not
meet criteria for Clinical PTSD but that had at least 1 Criterion
C (i.e. Avoidance/Numbing )symptom; AND 2) Clinical PTSD
cases.
Note: the definition of Subclinical PTSD in the MHSS is
confusing because it includes Clinical PTSD.
Summary of DSM-IV PTSD Findings from These Studies
The NCS, NCS-R and NESARC studies had more thorough and
comprehensive assessment of PTE exposure than the MHSS
and found approximately twice the lifetime PTE exposure
prevalence (i.e. 79.4% in the NCS and 79.7% in the NESARC ).
Past 12 month PTSD prevalence was approximately 5 times
lower in the MHSS than in the NCS-R , likely resulting from the
MHSS’s poor screening for PTEs, not administering the PTSD
module to many respondents who likely had undetected PTEs,
and possibly due to error variance introduced by clinician
administered semi-structured interviews.
Skip outs in the MHSS PTSD assessment made its estimate of
Subclinical PTSD severely flawed; the NESARC Partial PTSD
measure was better.
What about PTSD in DSM-5? Is It Really Different?
There have been changes in Criterion A, so DSM-IV
estimates of the Prevalence of PTE exposure are no longer
applicable.
There have also been other changes in the other PTSD
symptoms and diagnostic criteria, so DSM-IV estimates of
PTSD prevalence are no longer applicable.
Major Changes in DSM-5 Criterion A PTEs
PTEs no longer have to produce “fear, helplessness, or horror
(the A2 Criterion of DSM-IV), a Godsend for epi research!
Types of sexual violence events defined as PTEs were
expanded.
Learning about nonviolent, sudden, unexpected deaths of close
family members or friends is no longer a PTE unless the death
was violent or accidental.
New category of PTEs added involving work-related repeated or
extreme indirect exposure to aversive details of PTEs
experienced by others.
Explicit recognition that exposure to multiple PTEs is common
and that PTSD can occur in response to more than one PTE.
Other DSM-5 PTSD Changes
Three new symptoms (D3, D4, and E2) added and
four others (D1, D2, D7, and E1) modified.
Symptom-based criteria restructured from three in
DSM-IV to four in DSM-5.
Nonspecific PTSD symptoms required to develop or
worsen after exposure to PTE(s).
Acknowledgement that PTSD symptoms can
incorporate responses to more than one traumatic
event.
Obtaining DSM-5 PTSD Prevalence
Data: A Feasibility Online Survey
In conjunction with the DSM-5 PTSD Workgroup, we
developed a web-based assessment instrument designed to
collect data to evaluate the impact of proposed diagnostic
changes on PTSD prevalence.
This web-survey assessment tool was used with two samples.
The Web Surveys
The National Stressful Events Survey (NSES) sample
(n= 2953) was recruited from a national online panel
of U.S. adults. Methodology and findings are
described in a recent publication(Kilpatrick, Resnick,
Milinak, Miller, Keyes, & Friedman, 2013).
The Veterans Web Survey (VWS) sample (N=345)
was recruited from veterans in the Boston area who
had previously agreed to be contacted about research
studies at the National Center for PTSD. (See Miller
et. al, 2012 for more details).
Overview of NSES PTE and PTSD
Assessment Methodology
Self-administered but designed to mimic highly-structured
clinical interview with follow-up questions.
Measured all DSM-5 PTSD Criterion A events, DSM-IV A1
events scheduled for elimination, and DSM-IV A2.
Measured all 20 DSM-5 PTSD symptoms; follow-ups Qs
determined which traumatic event or events were involved
with each symptom, how recently symptom occurred, and
how disturbing symptom was during the past month
For new and modified symptoms, follow-up questions
determined which elements of the symptom they were
experiencing
Also measured functional impairment
Participation Rate
N=3,756 Accessed the Website 3,457 (92%) agreed to participate
2,953 (85.4% of those agreeing to participate; 78.6% of
those who accessed the site) completed the survey
NSES: Prevalence of Exposure to PTEs
Event Type: DSM-5 Criterion A N %
Disaster 1429 48.3%
Accident/fire 1462 49.5%
Exposure to hazardous chemicals 462 15.6%
Combat or war zone exposure 233 7.9%
Physical or sexual assault 1523 51.6%
Witnessed physical /sexual assault 926 31.3%
Witnessed dead bodies/parts unexpectedly 649 22.0%
Threat or injury to family or close friend due to violence/accident/disaster
950 32.1%
Death of family/close friend due to violence/accident/disaster 1450 49.1%
Work exposure 318 10.8%
Any DSM-5 Event 2613 88.4%
Threat or injury to family or close friend (non-violent) 86 2.9%
Sudden unexpected death (non-violent) 1638 55.4%
Other injury/life threat/other extremely stressful event 1222 41.3%
Any Event 2739 92.7%
Number of DSM-5 Criterion A
Events Experienced (Percent)
0
5
10
15
20
0 1 2 3 4 5 6 7 8 9 10
11.6
15.116.5 16.6
13.6
10.1
7.3
5
2.20.9 1
28 Number of events
Two Definitions of PTSD Caseness
Composite Event PTSD Caseness. Criteria B, C, D, and E met to a
combination of Criterion A Stressor Events (Must have at least one B,
one C, two D, and two E symptoms to some combination of DSM-5
Criterion A events); must also have functional impairment.
Same Event PTSD Caseness : Must have at least one B, one C, two D,
and two E symptoms to the same DSM-5 Criterion A Stressor event;
must also have functional impairment.
*Note: Parallel definitions were used to determine DSM-IV .All DSM-
IV definitions required A2 ,and event restrictions were based on DSM-
IV A1 as well as DSM-IV defined: at least 1 B, 3 C, and 2 D
Definition DSM-IV DSM-5
Composite PTSD Lifetime 10.6% 9.4%
Composite PTSD Past 12 Months 6.9% 5.3%
Same Event PTSD Lifetime 9.8% 8.3%
Same Event PTSD Past 12 Months 6.3% 4.7%
NSES
DSM-IV and DSM-5 PTSD Prevalence
Implications of NSES Findings for DSM-5 PTSD Prevalence Surveys
Developing and administering a self-administered structured
survey interview that measures all DSM-5 PTEs using
behaviorally specific Qs, all DSM-5 PTSD symptoms, and
PTSD-related distress/functional impairment is feasible and
can be done in a cost effective way.
The PTSD symptom assessment strategy was able to
determine whether each PTSD symptom occurred in response
to multiple PTEs, which would be useful in large scale surveys
given that most respondents have been exposed to more than
one PTE and that risk of PTSD is related to the number of
PTEs experienced.
The Way Forward: A Few Thoughts and Suggestions
Any epi study attempting to measure PTSD will be seriously
flawed if it does not include a thorough, detailed assessment of
exposure to PTEs. Avoid the understandable temptation to cut
corners in PTE assessment. If you do a good job, you can easily
determine how PTE exposure increases PTSD risk and risk of
other mental disorders measured in the survey.
MEASURE ALL DSM-5 PTSD SYMPTOMS!!! DO NOT USE
SKIP OUTS!!! If you don’t, you can’t obtain estimates of
Partial/Subthreshold/Subclinical PTSD.
PTSD assessment must move beyond the notion that PTSD
should be assessed to only one PTE.
The Way Forward (continued)
Although many believe that clinician-administered semi-
structured interviews are the gold standard for measuring PTSD
and other disorders, this not self-evidently true for large surveys.
Semi- structured clinical interviews are expensive and less
reliable than completely structured survey measures because
there is greater error variance due to different clinicians using
different follow-up probes and substituting their judgement for
what the respondent said.
We should consider using multi-mode sampling and data
collection strategies in surveys. There is no perfect sampling or
data collection strategy, but using face-to-face interviewers is
extremely expensive. Using other strategies would be more cost
effective and permit an increase in sample size.