Longitudinal invariance of posttraumatic stress disorder symptoms in adolescent earthquake survivors.

The present study examined the invariance of four models of posttraumatic stress disorder symptoms (PTSD) across time through an analysis of symptom ratings from the PTSD Checklist-Civilian version. Participants included 403 junior middle school students recruited from Sichuan, China at 5 and 11 months after the 2008 Sichuan earthquake. Confirmatory factor analysis using measurement and structural invariance testing found that four tested models were non-invariant (i.e., different) over time on PTSD's variable intercepts (indicating symptom severity) and residual error variances, but were invariant on PTSD's factor loadings and structural parameters. The two 4-factor intercorrelated models and the newly proposed 5-factor model were superior to the model defined in DSM-IV; however, the best fitting model was the newest proposed 5-factor model. These findings extend our understanding of PTSD's factor structure that the factor structure may be quite stable over time.