Posttraumatic Diagnostic Scale (PDS)

Abstract

The Posttraumatic Diagnostic Scale (PDS) is a widely utilized self-report measure designed to screen for the presence of Posttraumatic Stress Disorder (PTSD) following exposure to a traumatic event, or to evaluate the severity of symptoms and functional impairment in individuals already diagnosed with the disorder. Developed by Edna Foa and colleagues, the PDS aligns closely with the symptom criteria outlined in the DSM-IV. It assesses core symptom clusters including re-experiencing, avoidance, and hyperarousal, making it a crucial tool in clinical and research settings for rapid and reliable psychological assessment.

Keywords

Posttraumatic Stress Disorder, PTSD, Trauma Assessment, Self-report Scale, DSM-IV, Symptom Severity, Foa, Hyperarousal, Avoidance.

Authors

Edna B. Foa, Laurie Cashman, Lisa H. Jaycox, Kevin Perry.

Purpose

The primary purpose of the PDS is dual: first, to serve as a screening instrument for individuals who have identified themselves as victims of a potentially traumatic event; and second, to provide a quantified measure of symptom severity and associated functional impairment for patients already suffering from PTSD. This allows clinicians to track changes in symptom presentation over the course of treatment.

The scale is structured to guide the respondent through identifying their most distressing traumatic event before assessing specific symptom criteria based on that index event over the past month. The structure ensures the symptoms are directly linked to the identified trauma, improving diagnostic specificity. The instrument requires a reading age of approximately 13 years to ensure comprehension.

Construct

The PDS is constructed to measure the clinical presentation of PTSD as defined by the criteria of the DSM-IV. The instrument covers the three main clusters of symptoms characteristic of the disorder: Re-experiencing (intrusive thoughts, nightmares, flashbacks), Avoidance and Numbing (effortful avoidance of reminders, emotional detachment, diminished interest), and Hyperarousal (sleep disturbance, irritability, concentration difficulties, hypervigilance, and exaggerated startle response).

The assessment process includes an initial check of the A-criterion (Stressors) by asking about the nature of the traumatic event, including whether it involved physical injury or perceived danger. A diagnosis of PTSD is only made if all six DSM-IV criteria are endorsed. Failure to meet one or more criteria, or if too many items are omitted leading to an incomplete criterion, precludes a formal diagnosis using this scale.

Validity

The PDS has demonstrated strong psychometric properties supporting its validity, as documented in the foundational work by Foa, Cashman, Jaycox, and Perry (1997). Content validity is high because the items are deliberately framed to mirror the official diagnostic criteria for PTSD as established in the DSM-IV, utilizing accessible language for self-reporting.

The scale exhibits robust criterion validity, accurately discriminating between individuals with and without a clinical diagnosis of PTSD. Furthermore, the PDS has shown excellent convergent validity, correlating highly with other well-established measures of trauma and post-traumatic stress symptomatology.

Reliability

Reliability studies, including those conducted by Foa, Riggs, Dancu, and Rothbaum (1993), confirm the robustness of the PDS. The instrument demonstrates high internal consistency across its symptom clusters, ensuring that the individual items reliably measure the underlying constructs of re-experiencing, avoidance, and hyperarousal.

The scale is also known for its strong test-retest reliability, meaning that scores remain consistent over time in stable populations. This reliability makes the PDS an effective tool for monitoring symptom change and evaluating the efficacy of psychological interventions.

Factor Analysis

The structure of the PDS adheres to the three-factor model of PTSD outlined in the DSM-IV: Re-experiencing, Avoidance/Numbing, and Hyperarousal. The items are grouped conceptually to assess the frequency of distressing and intrusive thoughts, post-traumatic avoidance behaviors, and generalized hyperarousal symptoms, which formed the basis of the scale’s initial validation.

Instrument

Test Type: Self-report Diagnostic and Symptom Severity Measure

Format: Pencil and paper, or computerized scoring version. The PDS requires approximately 5 minutes for hand scoring.

Language Available: English (Original).

Population Group: Individuals exposed to a traumatic event, used for screening or monitoring symptom progression.

Age Group: Requires a reading age of approximately 13 years and older.

Population Details: Applicable to victims of various traumatic events, including combat, natural disasters, assault (sexual and nonsexual), and life-threatening illness.

Test Methodology: The scale involves a trauma exposure checklist, followed by assessment of peri-traumatic reactions, 17 items assessing symptom frequency (rated 0-3), and 9 items assessing functional interference (Yes/No). The Symptom Severity Score ranges from 0 to 51, derived from summing weighted responses to items 22 to 38. Cut-offs for severity are: < 10 (mild), 11–20 (moderate), 21–35 (moderate to severe), and > 36 (severe).

Keywords

PDS, Psychological Assessment, Clinical Screening, Hypervigilance, Intrusive Thoughts, Trauma Exposure Checklist, Symptom Severity Score.

Authors

Author ORCID Identifier: Information not provided in source content.

Affiliation Email addresses: Information not provided in source content.

Correspondence Address: Information not provided in source content.

Permissions & Fee and Test Year

The PDS was primarily validated in 1997, following the publication of the scale manual in 1995. The pencil and paper and computerized scoring versions of the PDS are available from the test distributor, National Computer Systems, Inc. (as per Foa, 1995). Prospective users should contact the distributor for current information regarding licensing, fees, and permissions for clinical or research use.

Reference’s

Foa, E. B. (1995). Posttraumatic Stress Diagnostic Scale Manual. United States of America: National Computer Systems, Inc.

Foa, E. B., Cashman, L., Jaycox, L. & Perry, K. (1997). The validation of a self-report measure of posttraumatic stress disorder: the Posttraumatic Diagnostic Scale. Psychological Assessment 9, 445–451.

Foa, E. B., Riggs, D.S., Dancu, C. V., and Rothbaum, B. O. (1993). Reliability and validity of a brief instrument for assessing post-traumatic stress disorder. Journal of Traumatic Stress, 6, 459-473.

The instrument is also referenced in Jessica M. Swinbourne’s thesis, “The Comorbidity Between Eating Disorders and Anxiety Disorders,” pages 320-322. The original PDF can be downloaded here: http://ses.library.usyd.edu.au/bitstream/2123/4026/1/j-swinbourne-thesis.pdf

An additional PDF resource related to the PDS is available here: https://d3gqux9sl0z33u.cloudfront.net/AA/AT/gambillingonjustice-com/downloads/220273/Posttraumatic_Diagnostic_Scale__PDS_.pdf

Items of the Posttraumatic diagnostic scale (PDS)

Please indicate how many of the following events you have witnessed or experienced:

• Accident or fire
• Natural disaster
• Nonsexual assault (known assailant) _
• Nonsexual assault (unknown assailant) _
• Sexual assault (known assailant) _
• Sexual assault (unknown assailant) _
• Combat or war zone _
• Sexual abuse _
• Imprisonment _
• Torture _
• Life-threatening illness _
• Other _

Please indicate which of the above events has disturbed you most in the past month and briefly describe the event in the space provided.

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

Please refer to the above event when answering the following questions.

1. Was there any physical injury to yourself as a result of the event? Yes / No
2. Was there any physical injury to someone else as a result of the event? Yes / No
3. Did you feel that your life or someone else’s life was in danger at the time of this event? Yes / No
4. Did you have a feeling of helplessness or terror at the time of the event? Yes / No

The following items refer to the frequency with which you have experienced these symptoms in the past month:

0= Once in a while Once a week or less, 1= Some of the time 2 times / week, 2= Half the time 3 – 4 times / week, 3=Almost always 5 + times / week

1. ha‎ving upsetting thoughts or images about the traumatic event that came into your head when you didn’t want them to
2. ha‎ving bad dreams or nightmares about the traumatic event
3. Reliving the traumatic event, acting or feeling as if it was happening again
4. Feeling emotionally upset when you were reminded of the traumatic event (e.g. feeling scared, sad, angry, guilty etc)
5. Experiencing physical reactions when you were reminded of the traumatic event (eg breaking out in a sweat, heart beating fast)
6. Trying not to think about, or have feelings about the traumatic event
7. Trying to avoid activities, people or places that remind you of the traumatic event
8. In ability to recall an important aspect of the trauma
9. ha‎ving much less interest or participating much less often in important activities
10. Feeling distant or cut off from people around you
11. Feeling emotionally numb (for example being unable to cry or unable to have loving feelings)
12. Feeling as if your future plans or hopes will not come true (for example you will not have a career, marriage, children or a long life)
13. ha‎ving trouble falling or staying asleep
14. Feeling irritable or ha‎ving fits of anger
15. ha‎ving trouble concentrating (for example drifting in and out of conversations, losing track of a story on television, forgetting what you read)
16. Being overly alert (for example checking to see who is around you, being uncomfortable with your back to a door etc)
17. Being jumpy and easily startled (for example when someone walks up behind you)

Please indicate whether your symptoms have interfered with the following areas within the past month:

1. Work Yes / No
2. Household duties Yes / No
3. Friendships Yes / No
4. Family relationships Yes / No
5. Fun and leisure activities Yes / No
6. Schoolwork Yes / No
7. Sex life Yes / No
8. General satisfaction with life Yes / No
9. Overall level of functioning Yes / No