Psychometric Properties of the Modified Posttraumatic Stress Disorder Symptom Scale among Women with Posttraumatic Stress Disorder and Substance Use Disorders Receiving Outpatient Group Treatments

The use of psychometrically sound measures to assess and monitor PTSD treatment response over time is critical for better understanding the relationship between PTSD symptoms and Substance Use Disorder (SUD) symptoms throughout treatment. We examined the psychometric properties of the Modified Posttraumatic Stress Disorder (PTSD) Symptom Scale, Self-Report (MPSS-SR).Three hundred fifty three women diagnosed with co-occurring PTSD (full or sub-threshold) and SUD who participated in a multisite treatment trial completed the MPSS-SR at pre-treatment, weekly during treatment, and posttreatment. Reliability and validity analyses were applied to the data.Internal consistency was excellent throughout the course of the trial demonstrating the MPSS-SR's high reliability. Strong correlations between MPSS-SR scores and the Brief Symptom Inventory and the Clinician Administered PTSD Scale (CAPS) severity scores demonstrated the MPSS-SR's convergent and concurrent validity. We conducted a classification analysis at posttreatment and compared the MPSS-SR at various cutoff scores with the CAPS diagnosis. A cutoff score of 29 on the MPSS-SR yielded a sensitivity rate of 89%, a specificity rate of 77%, and an overall classification rate of 80%, indicating the measure's robust ability to accurately identify individuals with PTSD in our sample at posttreatment.Findings support the use of the MPSS-SR as a reliable and valid tool to assess and monitor changes in PTSD symptoms over the course of treatment and as an alternative to structured clinical interviews to assess PTSD symptoms among populations with SUDs.