Clinician Administered PTSD Scale

The Clinically Administered PTSD Scale (CAPS) is an in-person clinical assessment for measuring posttraumatic stress disorder (PTSD). The assessment includes 30 questions administered by a trained clinician to assess for PTSD symptoms, including the frequency and severity of a patient's symptoms. The CAPS distinguishes itself from other PTSD assessments in that it can also assess for current or past diagnoses of PTSD.

Background

The CAPS was originally designed by the National Center for PTSD to be a more effective measure to assess PTSD. This measure was intended to be clinician-administered, and only administered by those clinicians with prior experience, training, and knowledge of PTSD.^[1] Previous measures of PTSD typically included self-report measures that the patient fills out without the help of a clinician. To have a clinically-administered PTSD scale was a novel concept in the PTSD field; it was modeled after the Hamilton Depression Scale,^[2] a clinician-administered scale to assess for depressive features. Some important features of the CAPS are:

1. Allows for a range of symptom severity rather than a dichotomous (yes/no) result. This allows for both a diagnosis as well as a sliding scale for clinicians to assess relative changes. It can be used for weekly changes or for a one-time diagnosis.
2. Creation of two scales: frequency and severity of symptoms. To fulfill a symptom criteria, a patient needs to have a certain frequency and severity of symptoms. This allows for a more refined level of measurement by measuring both how often a patient has symptoms and how severe they are.^[3]
3. Uniformity - the assessment was created in a way that would promote uniform administration of the assessment through clear questions and probes for interviewers.^[2]

Evolution

Table 1 – Versions of the CAPS by Diagnostic Statistical Manual version^[1][2]

The CAPS has developed over the years to keep up with changes in the widely used Diagnostic and Statistical Manual of Mental Disorders (DSM). The DSM is on its fifth version, the DSM-5 (May 2013) and serves as a guide to clinicians in diagnosing mental disorders. Currently, there are three versions of the CAPS-5 (Table 1). One version provides responses in the past month, one provides responses in the past week, and the last provides responses for the worst month (lifetime PTSD). There is also a version for children - the CAPS-CA-5^[4] Table 1 also shows the development of the CAPS by DSM version.

The CAPS1 was intended to monitor changes over a one-month period, whereas the CAPS-2 was developed to monitor changes over a week period. The CAPS-1 and CAPS-2 were later changed to the CAPS-DX and CAPS-SX respectively to avoid confusion over future versions. The CAPS-5 has two versions – one that can assess for one-week changes and one that can assess for one-month changes.^[2] The one-week changes may be more helpful for treatment providers to see change in symptom scores over time, whereas the one-month changes may be more helpful to assess for baseline PTSD.

The CAPS has been revised to the CAPS-5 to reflect current changes in the DSM-5. The CAPS is currently the gold-standard assessment for PTSD and is used widely through the VA for compensation and pension determinations.^[5] As described in Table 1, there are three versions of the CAPS, one to monitor monthly changes (often used for diagnosis), one to monitor weekly changes (often for assessing for time changes) and worst month (to assess for lifetime PTSD).

Current version and recent changes

The current CAPS-5 contains 30 questions about a person's PTSD symptoms. Each question asks about the frequency and the severity of each symptom. These questions are split into categories, called criterion. Each criterion has several questions, and scores for each criterion are added up at the end.^[6]

• Criterion A: A traumatic event
• Criterion B: Re-experiencing symptoms
• Criterion C: Avoidance symptoms
• Criterion D: Negative alterations in cognitions and mood
• Criterion E: Alterations in arousal and reactivity
• Criterion F: Disturbance lasted at least a month
• Criterion G: Disturbance causing impairment

Scoring

To meet criteria for PTSD, a patient must have:^[4]

• An index trauma/Criterion A event
• At least one Criterion B symptom (questions 1-5)
• At least one Criterion C symptom (questions 6-7)
• At least two Criterion D symptoms (questions 8-14)
• At least two Criterion E symptoms (questions 15-20)

Both criterion F and G must be met as well for a PTSD diagnosis.^[4] To meet criteria for a symptom, a patient must meet criteria in both frequency and intensity score for each item. Frequency and intensity and then combined to form a single severity score. Severity scores range from 0-4, with 0 being absent to 4 being extreme/incapacitating.^[4]

The National Center for PTSD provides information for clinicians to learn how to administer and score the CAPS. They recommend that, in addition to training, the CAPS be administered by clinicians familiar with PTSD.

Sample question and clinician follow-up

Sample Question: "In the past month, have you had any unwanted memories of (EVENT) while you were awake, so not counting dreams?")^[4]

• To calculate frequency, a patient may be asked "In the past month, have you had any unwanted memories of (EVENT) while you were awake, so not counting dreams?" or "How often have you had these memories in the past month?"^[4]
• To calculate intensity, a patient may be asked "How much do these memories bother you" and "Are you able to put them out of your mind and think about something else."^[4]

These frequency and intensity scores will get calculated together to create a severity score for each question. Total symptom severity is calculated by summing up all the individual item severity scores. For example, in the CAPS-IV scoring, to meet criteria for a symptom, the symptom must have an intensity score of 2 (on a scale or 0-4) or greater and a frequency score of 1 (on a scale of 0–4) or greater.

Limitations

• The CAPs can only assess for one trauma (one Criterion A event). This can present difficulties when a patient may have more than one trauma.
• The CAPS can be a lengthy interview taking up to 45–60 minutes. It may be difficult to find the personnel and time to conduct these interviews for clinics that have less resources available.
• The CAPS was developed using data from military veterans. Although it is used in non-veteran populations, there may be differences in traumas and symptoms between these populations.

References