The latent structure of post-traumatic stress disorder: tests of invariance by gender and trauma type.

BACKGROUND: Measurement invariance of Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV) post-traumatic stress disorder (PTSD) criterion symptoms was tested by gender and trauma type, assaultive and non-assaultive.
METHOD: Analysis was conducted using latent class analysis (LCA), based on findings that the three-class LCA model from Breslau et al. (Archives of General Psychiatry 2005, 62, 1343-1351) fits the data across the four groups best. The classes represent three levels of PTSD-related disturbance: no disturbance, intermediate disturbance and pervasive disturbance, with the last one approximating the DSM-IV PTSD diagnosis.
RESULTS: Analysis of measurement invariance showed that, with respect to gender, there was no evidence of differential symptom reporting within the same disturbance class. DSM-IV symptom indicators represent the latent structure of PTSD equally in males and females. We found that more female than male victims of assaultive violence experienced pervasive disturbance. In the absence of measurement variability associated with gender, the finding is likely to reflect a gender difference in susceptibility. The analysis of measurement invariance detected evidence of variability associated with trauma type. Victims of assaultive violence in the pervasive disturbance class report more severe distress (especially emotional numbing) than do victims of non-assaultive violence in the same class.
CONCLUSIONS: The finding of measurement bias associated with type of trauma raises questions about the applicability of a single definition for PTSD associated with assaultive violence and PTSD associated with traumatic events of lesser magnitude.