International Society for Traumatic Stress Studies

Clinician Administered PTSD Scale (CAPS)


Summary   

The CAPS is widely considered to be the "gold standard" in PTSD assessment. It is a structured interview providing a categorical diagnosis, as well as a measure of the severity of PTSD symptoms as defined by DSM-IV. It can be administered by any trained person and takes 30-60 minutes.

Author/Publisher Details   

National Center for PTSD, Boston, USA

Date   

Although first published in 1990, it is usually referenced as 1995.

Description   

The CAPS is a structured interview designed to make a categorical PTSD diagnosis, as well as to provide a measure of PTSD symptom severity. The structure corresponds to the DSM-IV criteria, with B, C, and D symptoms rated for both frequency and intensity; these two scores are summed to provide severity ratings. Additional questions assess Criteria A, E, and F. The CAPS-IV also inquires about associated features of guilt and dissociation; the latter allow the interview to be used for assessment of Acute Stress Disorder (e.g., Creamer et al., 2004; O'Donnell et al., 2004), although nothing has been published to date on the validity of this approach.

It takes 30-60 minutes to administer, (depending on the level of psychopathology) and slightly less to score. Training is required to administer this test, although all the necessary information for self-learning is available for free.

Although ideal for research settings, it can be a little cumbersome for use in routine clinical practice especially for those less experienced with the interview.

The CAPS DX is also available in German, French, Sewdish, Bosnian and Chinese. There are manuals for the French and Swedish versions (see below)

Scoring

It is recommended that the "1, 2" rule be used to determine a diagnosis; that is, a frequency score of 1 (scale 0 = "none of the time" to 4 = "most or all of the time") and an intensity score of 2 (scale 0 = "none" to 4 = "extreme") is required for a particular symptom to meet criterion (Weathers et al., 1999). The diagnosis is then made according to the DSM-IV algorithm (i.e., 1 "B" Criteria, 3 "C" Criteria, and 2 "D" Criteria, along with A, E, and F). A severity score for each symptom is calculated by summing the frequency and intensity scores, which can then be summed for all 17 symptom questions and/or for the three symptom clusters.

Alternative scoring options were suggested by Weathers et al., 1999, but they concluded that more complex systems were not well suited to routine clinical use. They note, however, that those options may be useful for differential diagnosis where a balance between false positives and false negatives is required.

Psychometrics

The CAPS has good psychometric properties across a wide variety of clinical populations and research settings (Weathers et al 2001).

Inter-rater reliability is high, ranging from 0.92 to 1.00 for "Frequency" ratings and 0.93 to 0.98 for "Intensity" ratings; the global severity correlation was 0.89. (Hovens et.al., 1994). Kappa for a categorical PTSD diagnosis is often 1.0 (i.e., 100% agreement; e.g., Mueser et.al., 2001).

Test-retest reliabilities range from .77-.96 for the three symptom clusters and from .90-.98 for the 17-item core symptom scale (Blake et.al., 1995). Using the standard 1/2 scoring rule described above, test-retest reliability (kappa) for a CAPS PTSD diagnosis was .63, with 83% agreement.

The CAPS demonstrates high internal consistency, with alphas for the three symptom clusters ranging from .85-.87, and .94 for the total score (Blake et.al., 1995).

Strong convergent validity has been demonstrated against the Structured Clinical Interview for DSM-IV (SCID) PTSD module (.83) and the PSS-I (.73) (Foa & Tolin, 2000). Overall agreement between a clinician-rated diagnosis and CAPS diagnosis was 79%; sensitivity was .74, while specificity was .84 (Hovens et.al., 1994). Several studies have reported strong agreement between the CAPS and various PTSD self report scales.

 

Non-English Translations   

Chinese (Chu, unpublished 2004, Wu et al 2004, 2008)
The CAPS-DX was translated and back translated for a masters dissertation at the University of Hong Kong in 2004. The questions spoken by the clinicians are Cantonese and all other instructions are in Chinese with traditional Chinese font. There is no manual available. This version of the CAPS-DX has been used in several studies including a current RCT for survivors of road traffic accidents. There are no papers specifically on the psychometric properties of the Chinese CAPS-DX but it has been validated against the IES-R (Wu et al. 2004) and PCL (Wu et al., in press). The masters dissertation of Chu (unpublished) reports that the inter-rater reliability for symptom clusters was 93%, and for a full diagnosis of PTSD based on DSM-IV criteria was 100%. Enquiries about the Chinese version should be directed to: Kitty Wu: wukyk@ha.org.hk

French (Serge Saint-Onges, unpublished)
The CAPS-DX and the manual were translated by Saint-Onges, a professional translator, and back translated by a bilingual psychologist. There are no known papers using the French CAPS. Enquiries about the French version should be directed to:
saintonges@videotron.ca

German (Schnyder, U., & Moergeli, H. (2002)
The DSM-IV version of the CAPS (Blake et al., 1990) was translated into German by the first author and back-translated by a psychologist experienced in psychiatric epidemiology but unfamiliar with traumatic stress research and the CAPS. The Manual was not translated as it is expected that most users can read the English version. Schnyder & Moregeli (2002) report that the German version of the CAPS is a reliable instrument for the assessment of posttraumatic stress disorder symptomatology in accident victims. Internal consistency proved to be comparable to that of the original English version: Cronbach's alpha was .88 at T1 and .92 at T2 for the CAPS total score. The CAPS correlated significantly with the validated German version of the Impact of Event Scale (IES). Enquiries about the German version should be directed to: uschnyd@psyp.unizh.ch

Swedish (Paunovic, N., & Ost, L, (2005)
The CAPS-DX was translated into Swedish by the first author. The second author, a professor in clinical psychology with extensive experience in writing and speaking in American English, back-translated it. There is no Swedish manual, and users are referred to the English one, Paunovic & Ost report full psychometrics in the 2005 paper. In summary the CAPS-DX evidenced promising internal consistency and significant correlations with the PSS-SR and the IES-R. Additionally, each subscale of the CAPS-DX (intrusion, avoidance/numbing, and arousal) was significantly correlated with the corresponding subscales of the PSS-SR and the IES-R. Enquiries about the Swedish version should be directed to: Nenad Paunovic, Associate professor, Department of Psychology, Stockholm University, Stockholm, Sweden sonepaunovic@hotmail.com

Bosnian - Charney, M. and Keane, T. (2007)
The CAPS-DX  was translated into Bosnian and then back translated using a panel of three native Bosnian speakers who were fluent in English. This process is described in detail in the paper. The manual was not translated. The psychometric properties of this version of the CAPS were tested in a Bosnian refugee sample. Charney & Keane report that the "study demonstrated optimal fit with a 2-factor model of posttraumatic stress disorder (PTSD); the authors also found high reliability with a coefficient alpha of 0.92 and strong convergent validity with instruments measuring depression, anxiety, and levels of psychosocial functioning"

Note that the interview has been posted in Microsoft Word format because there are some formatting errors on pages 2.21 and 22 that cannot be rectified by the dissemination team or the authors. If you are able to read Bosnian and correct the interview formatting, it would be much appreciated if you could return a copy to the authors. Enquiries about the Bosnian version should be directed to: mecharney@partners.org, Dr Meredith Charney, Department of Psychiatry, Massachusetts General Hospital, Boston, MA

Key/Core References   

Blake, D. D., Weathers, F. W., Nagy, L. M., Kaloupek, D. G., Gusman, F. D., Charney, D. S., & Keane, T. M. (1995). The development of a clinician-administered PTSD scale. Journal of Traumatic Stress, 8, 75-90.

Blake, DD, Weathers ,FW, Nagy LM, Kaloupek D, Klauminzer G, Charney DS, Keane TM, & Buckley TC. (2000). Clinician-Administered PTSD Scale (CAPS) Instruction Manual. Boston, MA: National Center for PTSD.

Creamer, M., O'Donnell, M., & Pattison, P. (2004). The relationship between acute stress disorder and posttraumatic stress disorder in severely injured trauma survivors. Behaviour Research and Therapy, 42, 315-328.

Foa, E. B., & Tolin, D. F. (2000). Comparison of the PTSD Symptom Scale-Interview Version and the Clinician-Administered PTSD scale. Journal of Traumatic Stress, 13, 181-191.

Hovens, J. E., Van Der Ploeg, H. M., Klaarenbeek, M. T. A., Bramsen, I., Schreuder, J. N., & Rivero, V. V. (1994). The Assessment of Posttraumatic Stress Disorder: with the Clinician Administered PTSD Scale: Dutch Results. Journal of Clinical Psychology, 50, 325-340.

Mueser, K. T., Rosenberg, S. D., Fox, L., Salyers, M. P., Ford, J. D., & Carty, P. (2001). Psychometric evaluation of trauma and posttraumatic stress disorder assessments in persons with severe mental illness. Psychological Assessment, 13, 110-117.

O'Donnell, M., Creamer, M., Pattison, P., & Atkin, C. (2004).Psychiatric morbidity following injury. American Journal of Psychiatry, 161, 507-514.

Weathers, F. W., Keane, T. M., & Davidson, J. (2001). Clinician-administered PTSD scale: A review of the first ten years of research. Depression and Anxiety, 13, 132-156.

Weathers, F. W., Ruscio, A. M., & Keane, T. M. (1999). Psychometric properties of nine scoring rules for the Clinician-Administered Posttraumatic Stress Disorder Scale. Psychological Assessment, 11, 124-133.

Translations

Bosnian
Charney, M.E and Keane, T.M (2007) Psychometric Analyses of the Clinician-Administered PTSD Scale (CAPS)--Bosnian Translation. Cultural Diversity and Ethnic Minority Psychology. 13 (2) 161-168.

Chinese
Chu LY. Coping, appraisal and post-traumatic stress disorder in motor vehicle accident. Unpublished master's thesis, University of Hong Kong. Hong Kong, China, 2004. [translation was done in the context of this thesis].

Wu KK, Chan KS. (2004) Psychometric Properties of the Chinese version of Impact of Event Scale - Revised (IES-R). Hong Kong Journal of Psychitry14, 2-8.

Wu, KK. et al. (In press) Psychometric Properties and Confirmatory Factor Analysis of the Posttraumatic Stress Disorder Checklist (PCL) for Chinese Survivors of Motor Vehicle Accident Hong Kong Journal of Psychiatry.

French
Unpublished

German
Schnyder, U., & Moergeli, H. (2002). German version of Clinician-Administered PTSD Scale. Journal of Traumatic Stress, 15(6), 487-492.

Swedish
Paunovic, N., & Ost, L, (2005) Psychometric Properties of a Swedish Translation of the Clinician-Administered PTSD Scale-Diagnostic Version. Journal of Traumatic Stress 18 (2) 161-164

Further Information   

Training for administering the CAPS is available through the instruction manual, and also on a downloadable CD-ROM, although since the download is large and time consuming it is also available for purchase. See:
http://www.ptsd.va.gov/professional/assessment/overview/caps-training.asp

Manual Available Only to ISTSS Members  

CAPS Manual in English or French

View Tool   

This resource should be used in an ethical and responsible manner and should be used only for the purpose(s) for which it has demonstrable validity. Please observe copyright where indicated and reference it appropriately.

Available Only to ISTSS Members

English Version of CAPS
Chinese Version of CAPS
German Version of CAPS
French Version of CAPS
Swedish Version of CAPS 
Spanish Version of CAPS