The structure of posttraumatic stress disorder: latent class analysis in 2 community samples.

CONTEXT Latent structure analysis of DSM-IV posttraumatic stress disorder (PTSD) can help clarify how persons who experience traumatic events might be sorted into clusters with respect to their symptom profiles. Classification of persons exposed to traumatic events into clinically homogeneous groups would facilitate further etiologic and treatment research, as well as research on the relationship of trauma and PTSD with other disorders. OBJECTIVES To examine empirically the structure underlying PTSD criterion symptoms and identify discrete classes with similar symptom profiles. DESIGN Data on PTSD symptoms from trauma-exposed subsets of 2 community samples were subjected to latent class analysis. The resultant classes were studied in associations with trauma type and indicators of impairment. SETTING The first sample is from the Detroit Area Survey of Trauma (1899 trauma-exposed respondents with complete data) and the second is from a mid-Atlantic study of young adults conducted by The Johns Hopkins University Prevention Research Center, Baltimore, Md (1377 trauma-exposed respondents with complete data). PARTICIPANTS Respondents in the 2 community samples who experienced 1 or more qualifying PTSD-level traumatic events. MAIN OUTCOME MEASURES Number, size, and symptom profiles of latent classes. RESULTS In both samples, analysis yielded 3 classes: no disturbance, intermediate disturbance, and pervasive disturbance. The classes also varied qualitatively, with emotional numbing distinguishing the class of pervasive disturbance, a class that approximates the subset with DSM-IV PTSD. Members of the pervasive disturbance class were far more likely to report use of medical care and disruptions in life or activities. CONCLUSIONS The 3-class structure separates trauma-exposed persons with pervasive disturbance (a class that approximates DSM-IV PTSD) from no disturbance and intermediate disturbance, a distinction that also helps identify population subgroups with low risk for any posttrauma disturbance. The results suggest that the structure of PTSD is ordinal and configurational and that emotional numbing differentiates the class with pervasive disturbance. These results should motivate prospective research of persons who have experienced trauma to trace the emergence of posttrauma symptoms and the timing of emotional numbing relative to other symptoms.