Validation of a brief screen for Post-Traumatic Stress Disorder with substance use disorder patients

Abstract

To evaluate a 4-item screen for Post-Traumatic Stress Disorder (PTSD) for use with patients diagnosed with substance use disorders, 97 patients were recruited from substance use disorder treatment clinics at a large medical center. Participants completed the self-administered 4-item PTSD screen. Psychologists interviewed patients using the Clinician Administered PTSD Scale (CAPS). Sensitivity and specificity were calculated using the CAPS as the criterion for PTSD. Results were compared to chart diagnoses.

The prevalence of PTSD was 33%. The screen identified 91% of PTSD cases, where only 25% of PTSD cases were diagnosed in the medical chart. The screen demonstrated good test–retest reliability (r = .80) and yielded a sensitivity of .91 and specificity of .80 using a cut score of 3. Likelihood ratios indicate that the screen has good ability to detect PTSD in this population, and that patients with positive screens that do not meet criteria for PTSD are likely to report significant subthreshold symptoms. Screening for PTSD in SUD treatment settings is time efficient and may increase the detection of previously unrecognized PTSD.

Introduction

Individuals with Post-Traumatic Stress Disorder (PTSD) are at more than 4 times the risk for substance use disorders (SUD) than the general population (Chilcoat & Breslau, 1998) and are over represented in SUD treatment settings. Substance abuse patients with comorbid PTSD present with greater drug abuse severity (Clark, Masson, Delucchi, Hall, & Sees, 2001) demonstrate greater trauma and drug cue-elicited drug craving (Coffey et al., 2002, Saladin et al., 2003) and have poorer SUD treatment outcomes (Ouimette, Brown, & Najavits, 1998) than SUD patients without PTSD. Less than one-third of PTSD-SUD patients achieve abstinence 2 years following treatment (Ouimette, Moos, & Finney, 2000) and recent research suggests that an exacerbation of PTSD symptoms may be the most important factor in predicting relapse following substance abuse treatment (Ouimette, Moos, & Finney, 2003).

Improving detection of PTSD is a necessary first step to effectively treat comorbid patients. Research suggests that PTSD most often goes unrecognized in SUD treatment settings (Dansky, Roitzsch, Brady, & Saladin, 1997). Substance use may mask PTSD symptoms, or clinicians may be reluctant to explore traumatic material in substance using patients. However, comorbid patients that receive PTSD treatment are 3.7 times more likely to achieve long-term remission from substance use (Ouimette et al., 2003) as compared to comorbid patients whose PTSD goes untreated.

The current study focuses on a 4-item screen for DSM-IV PTSD that is widely used in VA settings (Prins et al., 2004). The PC-PTSD screen was designed to detect PTSD in primary care, and focuses on meaningful, empirically derived symptom clusters of PTSD: re-experiencing, numbing, avoidance, and hyperarousal (Asmundson et al., 2000, Walker et al., 2002). Because 90% or more of the general population will experience a traumatic event in their lifetime, assessment of trauma exposure was excluded from the screen items for its lack of specificity to the PTSD diagnosis (Breslau et al., 1998). In primary care, the PC-PTSD has an optimal cut score of 3, which yields a sensitivity of .78, a specificity of .87, and an 83% agreement with a full diagnostic interview for PTSD. Diagnosis of anxiety and depressive disorders is generally more difficult in patients with substance use disorders (Anthenelli & Schuckit, 1993), and additional data is needed to determine the utility of this screen to identify PTSD in this population. The goal of the current study was to evaluate the psychometric properties the PC-PTSD screen among patients in SUD treatment settings.