The NESARC PTSD module covers the DSM-IV criteria and includes additional questions that are not required for diagnosis; some criterion symptoms are covered by more than one item. We used the NESARC interview data to diagnose PTSD, applying the DSM-IV criteria. When two items are used in the interview to ascertain a single symptom, replies were combined as one item rather than counted as two symptoms. The PTSD module in NESARC is closely modeled on the National Institute of Mental Health’s Diagnostic Interview Schedule and the World Health Organization Composite International Diagnostic Interview (CIDI). High concordance was reported between the ascertainment of CIDI/PTSD by lay interviewers and independent clinical interviews, using the Clinician Administered PTSD Scale. The positive predictive value was 0.75, the negative predictive value was 0.97, and the odds ratio was 94.8 (Breslau et al. 1998a).
