The European Network for Traumatic StressTraining & Practice

www.tentsproject.eu

The Prevalence of PTSD

Maja Lis-Turlejska

Learning outcomes (1)

• Describe the concept of prevalence and other terms used in epidemiological studies: e.g. incidence rate, and odds ratio (relative risk)

• Describe a change regarding the prevalence of PTSD studies – from relatively small-scale studies under clinical conditions to the research on general population in different countries

Learning outcomes (2)

• Describe the change in prevalence studies regarding exposure to PTEs and how it is connected with the Criterion A of PTSD definition

• Give examples of some often used tools to measure PTSD and exposure to potentially traumatic events (PTEs)

Learning outcomes (3)

• Describe the differences between types of trauma regarding their risk for developing PTSD

• Describe the prevalence rates of PTSD (and PTEs) in the studies done recently in several European countries as well as in other countries of the world

What is prevalence?

• Prevalence in epidemiological studies of a disorder means a percentage of a population that has a disorder at a given time

• In many studies prevalence is discussed in terms of lifetime prevalence

• Also data are provided on current prevalence of PTSD in a given time frame, usually one year

Cumulative incidence

• Cumulative incidence („risk”) is the proportion of people that develop a disorder over time among only the population at risk for that disorder

• Large cumulative incidence (a large amount of new disorder occurrence) occurring over a short period of time has different intervention implications then if it is observed over a very long period of time

Risk ratio

• A cumulative incidence ratio („risk ratio” or „relative risk”) is a relative measure of the cumulative incidence of disorder in a group exposed to a certain factor compared to the cumulative incidence of a disorder in a group that is unexposed to that factor

Measuring prevalence of PTSD and PTEs

• In studies of prevalence measures of exposure to trauma (potentially traumatic - event – PTE) and PTSD are used

PTSD measures

• There are two main types of measures used in PTSD assessment (evaluation):

- Structured Interviews (e.g. CAPS)

- Self-report Questionnaires (e.g. IES)

Measurement of traumatic event exposure (2)

• DSM-IV introduced two types of changes:

• The range of events considered as potentially giving rise to PTSD was broadened, relative to previous definitions

• On the other hand, special significance was accorded to the individual’s reaction to the stressor

Measures of exposure to PTEs

• Data relating to the prevalence of traumatic events is dependent not only on the definition of trauma adopted but equally on the measurement tools being used

Prevalence studies in samples of the general population

• In the mid-1990s a significant change took place regarding epidemiological research relating to PTSD and – it therefore follows – exposure to trauma

• This development was from relatively small-scale research under clinical conditions, via the 1993 research commissioned by the US Congress into a representative sample of Vietnam War veterans, culminating in research on the general population, or on geographically-based communities

Measurement of traumatic event exposure

• It is only during the last 20 years that alongside PTSD-measurement tools there have appeared scales and questionnaires designed to measure exposure to various kinds of traumatic events

• Before - research on PTSD has focused on those suffering from traumatic experiences related to participation in combat or war, or in the wake of other specific types of trauma, such as natural disasters, rape and criminal assault

Why the studies on prevalence are important ?

• The work done to establish the PTEs and PTSD in the general population permits:

- to estimate the prevalence of exposure to trauma and of PTSD in the entire population and its various subgroups

- it also enables the identification of the types of trauma having the greatest probability of leading to PTSD

National Comorbidity Survey (USA)

• Data from research on samples of the general population, initially undertaken only in the US; later on began to be carried out in other Western countries also

• In often cited National Comorbidity Survey (NCS) (Kessler, et al., 1995) interviews were administered to a representative national sample of persons aged 15-54 years

National Comorbidity Survey (USA)

• Lifetime prevalence of PTSD: 7,8%

• 60.7% of men and 51.2% of women reported at least one traumatic event

Traumas most commonly associated with PTSD in NCS

NSR-Replication

• Kessler et al. (2005) presented the data from the replication of NCR conducted between 2001-2003, on the US national sample of adults, done with the fully structured WHO Mental Health Survey version of CIDI

• Total PTSD life-time prevalence rate was

6,8 %. Prevalence estimates varied significantly with age. For PTSD the highest rate: 9,2% was for a group aged 45-59

Studies on prevalence of PTSD in Europe

European Study of the Epidemiology of Mental Disorders (ESEMeD)

- 21,425 adults nationally representative of six European countries (Belgium, France, Germany, Italy, the Netherlands and Spain). PTSD life-time prevalence: Total= 1.9%, (M=0,9%; F= 2.9 %) (Alonso et al., 2004).

- 12 months: Total =1.1% (M=0.5%; 1,7%F (Darves-Bornoz et. al., 2008)

Prevalence studies in different European countries

• Study on the lifetime prevalence of PTEs and PTSD in the Netherlands (de Vries & Olff, 2009)

- The lifetime prevalence of any potential trauma: 80.7%

- The lifetime prevalence of PTSD: 7.4%

The Zurich Cohort Study

• The weighted lifetime prevalence of PTE in 1999 was 28%. Of the persons who reported exposure to PTE (criterion A), none met all the remaining criteria for PTSD (Hepp et al., 2006)

PTSD among children and adolescents

• Studies among children who experienced specific traumas indicate that children may have higher prevalence rates of PTSD then adults in the general population

• US National Survey of Adolescents: six- months prevalence: 3.7% for boys and 6.3% for girls (Killpatrick et al., 2003)

Prevalence of PTEs and PTSD among Danish adolescents

• Ask Elklit (2002) studied prevalence of traumatic and life events in relation to PTSD in a Danish national representative sample of 390 eight-grade students aged 13 to 15

• 87% of females and 78% of males were exposed to at least one event

• Lifetime prevalence of PTSD (according to DSM-III-R) was 9% (5.6% males and 12.3% females)

Study in 4 postconflict settings

Epidemiological survey conducted among survivors of war or mass violence (aged >16 years) who were randomly selected from community populations in Algeria (n=653), Cambodia (n=610), Ethiopia (n=1200), and Gaza (n=585).

• The prevalence rate of PTSD was 37.4% in Algeria, 28.4% in Cambodia, 15.8% in Ethiopia, and 17.8% in Gaza (de Jong et al., 2001)

Prevalence of PTSD in Eastern European countries

• There is no data available from the epidemiological studies done in Eastern European countries

• Some data however done on non-clinical samples in Poland and Lithuania show higher rates of PTSD then in the studies from Western Europe (Lis-Turlejska, 2005; Kazlauskas,et. al, 2006)

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