Differentiating post-traumatic stress disorder (PTSD) from major depression (MDD) and generalized anxiety disorder (GAD).

Questions about the differential diagnosis of Post-Traumatic Stress Disorder (PTSD) have been raised since this category was reformulated in DSM-III (APA, 1980). Clinicians have reported difficulties distinguishing PTSD from other categories, particularly from Major Depressive and Generalized Anxiety Disorders (MDD and GAD). Diagnostic validity can be established in several ways (e.g., through clinical descriptive studies, laboratory experiments, family history studies, etc.). In this paper, we describe one approach to validation thus far not applied to PTSD: This approach centers directly on whether clinicians can distinguish PTSD from other diagnostic categories. Experienced clinicians were asked to rate the extent to which a common set of 90 symptom items characterized PTSD, MDD, and GAD. Ratings were analyzed with multivariate and univariate analyses of variance and covariance, multiple discriminant function analysis, and factor analysis; moreover, characteristics of rates were examined for possible influences. Results indicated that clinicians readily distinguish PTSD from MDD and GAD as well as MDD from GAD. Findings are presented in terms of univariate analyses, 34 best discriminating items, and factors specifying dimensions differentiating the syndromes of PTSD, MDD, and GAD. Rater characteristics did not influence diagnostic accuracy, although significant differences in magnitude of symptom intensity were found.