Assessment and Diagnosis of Posttraumatic Stress Disorder

Posttraumatic stress disorder (PTSD) is a chronic and debilitating mental condition that develops in response to catastrophic life events, such as military combat, sexual assault, and natural disasters. The symptoms of PTSD are divided into 3 symptom clusters: reexperiencing, avoidance, and hyperarousal. In addition, trauma survivors often experience guilt, dissociation, alterations in personality, difficulty with affect regulation, and marked impairment in ability for intimacy and attachment.^1,2 Disorders comorbid with PTSD include depression, substance abuse, other anxiety disorders, and a range of physical complaints.^3,4

Over the past several decades, considerable progress has been made in the development and empirical evaluation of assessment instruments for measuring trauma exposure and PTSD as well as related syndromes, such as acute stress disorder. The measures that have been developed, including questionnaires, structured interviews, and psychophysiological procedures, have been extensively validated and many have been widely adopted internationally. PTSD assessments were developed to be psychometrically sound; to collect information from multiple sources across response channels; and to use across different trauma populations, settings, genders, ethnic groups, and cultures.^5-8

This article, based on a comprehensive review by Weathers and associates,⁹ provides a selective and brief summary of trauma and PTSD assessments in adults.

Diagnosing PTSD

The current diagnostic criteria for PTSD include¹⁰:

• Exposure to a traumatic stressor (criterion A)

• The development of a characteristic syndrome involving reexperiencing, avoidance and numbing, and hyperarousal symptoms (criteria B through D)

• Duration of at least 1 month (criterion E)

• Clinically significant distress or impairment in social or occupational functioning (criterion F).

A comprehensive assessment of PTSD evaluates all of the diagnostic criteria, assesses associated features and comorbid disorders, and establishes a differential diagnosis. Although some of these tasks can be accomplished with self-report measures, most are best accomplished with a structured interview. Clinical interviews provide opportunities to ask follow-up questions, to clarify items and responses, and to use clinical judgment in making the final ratings.

It is necessary to establish that an individual has been exposed to an extreme stressor that satisfies the DSM-IV definition of trauma as described in criterion A. The patient must have directly experienced the event, witnessed it, or learned about it indirectly; the event must have been life-threatening, involved serious injury, or threatened physical integrity; and it must have triggered an intense emotional response of fear, horror, or helplessness.

In addition to identifying an index event for symptom inquiry, it is important to assess for exposure to other traumatic events across the life span. Exposure to multiple lifetime traumas is typical, and previous traumas may influence reactions to the index event.^3,11 The target trauma is identified as the one that is currently causing the most frequent and severe symptoms. The 17 PTSD symptoms are then rated in relation to that event (Table 1). In addition to evaluating the diagnosis and severity of PTSD, a comprehensive assessment often includes an evaluation for the presence of comorbid disorders and associated features.

Several measures are available to help diagnose PTSD and assess its severity. These include structured interviews, self-report measures, and multiscale personality inventories (Table 2).

CHECKPOINTS

■ Posttraumatic stress disorder (PTSD) assessment instruments are psychometrically sound, can be used to collect information from multiple sources, and can be used to measure different trauma populations.

■ Although structured interviews, self-report measures, and multiscale personality inventories are available for assessing PTSD, a structured interview is recommended to evaluate all of the diagnostic criteria, assess associated features and comorbid disorders, and establish a differential diagnosis.

■ In addition to identifying an index event for symptom inquiry, it is important to assess patients for exposure to other traumatic events across their life span.

Structured interviews

The comprehensive Structured Clinical Interview for DSM-IV (SCID) is designed to help diagnose all the major DSM-IV disorders.¹² As with all SCID modules, the PTSD module maps directly onto DSM-IV diagnostic criteria. The SCID PTSD module appears to have good reliability and convergent validity in a variety of samples and settings.^13-15

The Clinician-Administered PTSD Scale (CAPS), which was developed in 1989 at the National Center for PTSD, is a comprehensive structured interview for PTSD.^16,17 The CAPS consists of 30 items: 17 items assess DSM-IV symptoms of PTSD; 5 assess onset, duration, subjective distress, and functional impairment; 3 assess overall response validity, symptom severity, and symptom improvement; and 5 assess associated symptoms, including trauma-related guilt and dissociation. In addition, the CAPS assesses criterion A by means of the Life Events Checklist, which screens for possible trauma exposure. It also includes a trauma inquiry section that evaluates criterion A and identifies an index event for symptom inquiry. At the symptom level, the CAPS yields continuous and dichotomous scores for each item, and at the syndrome level it yields a continuous measure of overall PTSD symptom severity in addition to a dichotomous PTSD diagnosis.