Comparing the DAPS and PDS assessments for PTSD

¶ … Post-Traumatic Stress Disorder

The diagnosis of posttraumatic stress disorder (PTSD) was first included in the third edition of the Diagnostic and Statistical Manual of Mental Disorders due to the need to describe the adverse reactions experienced by combat troops returning from Vietnam (Courtois, 2008). The National Institutes of Mental Health (NIMH, 2011) defines PTSD as an "anxiety disorder that can develop after exposure to a terrifying event or ordeal in which there was the potential for or actual occurrence of grave physical harm." Traumatic events that may trigger PTSD include violent personal assaults, natural or human-caused disasters, accidents, and military combat. People with PTSD have persistent frightening thoughts and memories of their ordeal, may experience sleep problems, feel detached or numb, or be easily startled. According to the NIMH, 6.8% of adults will experience PTSD over their lifetimes, and 36% of these cases will be severe. Additionally, 4.0% of 13 to 18-year-olds will experience PTSD. Therefore, it is important that there are valid and reliable instruments available to assess this condition. This paper will compare two of these assessments: the Detailed Assessment of Posttraumatic Stress (DAPS) and the Posttraumatic Stress Diagnostic Scale (PDS).

Detailed Assessment of Posttraumatic Stress

The DAPS is a self-report measure that is designed for use with individuals who have experienced a significant psychological stressor. The instrument measures the extent of trauma exposure and post-traumatic response (Smith). The DAPS is a pencil and paper assessment which contains 104 questions (Boothroyd). These questions take between 20 and 30 minutes to complete and can be scored and profiled in about 20 minutes (Boothroyd). The test is designed to be administered to adults who read on at least a sixth-grade level. Once scored, the instrument measures thirteen scales. According to Boothroyd, two of these scales, positive bias and negative bias, are designed to identify respondents who underreport and over report their symptoms. The other scales include three trauma-specific subscales (Relative Trauma Exposure, Peritraumatic Distress, Peritraumatic Dissociation), five posttraumatic scales (Reexperiencing, Avoidance, Hyperarousal, Posttraumatic Stress total, Posttraumatic Impairment), and three associated feature scales (Traumatic-Specific Dissociation, Substance Abuse, and Suicidality) (Smith). According to Smith, the test may be administered and scored by nonclinical personnel, but the interpretation of scores and profiles requires graduate training in psychology and test interpretation.

Psychometric Properties

The normative sample for the DAPS included 620 participants from a stratified random sampling from Department of Motor Vehicles registries and telephone listings (Smith). Of these 620 participants, 446 reported at least one DSM-IV-TR experience in the past. Smith also reports that 70 university students were sampled as well. The assessment authors conducted another sample to measure reliability. The study included 257 undergraduate students, 191 clinical patients, and 58 participants recruited through flyers and newspaper advertisements (Smith). Both samples were primarily female, 74% in the university sample and 80% in the community sample, as well as Caucasian, 84% in the university sample and 77% in the community sample (Smith). The mean age was 19.6 in the university sample and 35 in the community sample.

Boothroyd reports the following reliability and validity data for the DAPS. The majority of the 13 scales have Cronbach coefficients above .8, and internal consistency estimates on the Positive Bias scale range from .61 to .80. The internal consistency coefficients for the Negative Bias and Relative Trauma Exposure scale range from .49 to .67. Additionally, three types of evidence to support validity of scores are provided: the relationship of DAPS scores with conceptually important variables, its convergence with similar measures, and its discrimination from less-related measures. Smith adds that the correlation between the symptom scales and the symptom scales of other inventories are in the .60 to .80 range.

The normative sample for the PDS include 248 participants recruited from Veterans Administration hospitals, anxiety and PTSD treatment clinics, women's shelters, emergency/trauma centers, fire stations, ambulance corps, and residential rehabilitation centers who had experienced a trauma-inducing event more than a month prior to the study (Axford). Doll adds that the study was limited to five East Coast states and two Midwestern cities. Additionally, low- and upper-income subjects were somewhat overrepresented while Hispanics and other minorities were somewhat underrepresented in the study (Doll).

Doll reports the following reliability and validity data for the PDS. The internal consistency alpha for the Symptom Severity Score was .92, and test-retest reliability was 87.3%. The validity study demonstrated that decisions made with the PDS agreed with those made with the Structured Clinical Interview for DSM-III-R 79% of the time. Doll adds that the PDS correctly identified PTSD 82.0% of the time and correctly identified non-PTSD 76.7% of the time.

Evaluation

Both assessments seem to have adequate reliability and validity data. In addition, both assessments are correlated to DSM diagnostic criteria. All of the reviewers cited in this paper found that they are both promising instruments for assessing and monitoring progress of subjects with PTSD. However, there is some concern that the PDS only includes one small study for its normative sample as well as its reliability and validity studies; therefore, Doll recommends that the instrument is not yet ready for clinical use and should be limited to use in research until further validity studies can be conducted. Therefore, at this time the DAPS is a better instrument for assessing and monitoring PTSD in both a research and clinical setting.

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