The symptom structure of panic disorder: a trial using factor and cluster analysis.

Using cluster analysis of 207 patients with panic disorder (PD), we investigated the relationships between several panic symptoms at the time of panic attacks, which included anticipatory anxiety, agoraphobia, and 13 clinical symptoms based on the Diagnostic and Statistics Manual-III-Revised. Cluster analysis revealed three panic symptom clusters: cluster A (dyspnea, choking, sweating, nausea, flushes/chills); cluster B (dizziness, palpitations, trembling or shaking, depersonalization, agoraphobia, and anticipatory anxiety); and cluster C (fear of dying, fear of going crazy, paresthesias, and chest pain or discomfort). Generally, cluster A was comprised exclusively of physiological symptoms, among which respiratory symptoms were prominent, cluster B included both panic and non-panic symptoms such as agoraphobia and anticipatory anxiety, and cluster C was comprised chiefly of fear symptoms.