Longitudinal course of posttraumatic stress disorder in Chileans

Background: There are increasing numbers of trauma survivors in the population, therefore, it is crucial to understand who is most at risk for developing PTSD. The objective of this study was to examine the role that pre-existing psychopathology plays in developing PTSD after a natural disaster.

Methods: The current study utilizes secondary data from a prospective 4-wave longitudinal cohort study (years 2003-2011) of Chilean adults (N=1,708). At baseline, participants completed the Composite International Diagnostic Interview (CIDI), a comprehensive psychiatric diagnostic instrument. In the midst of the study (2010), the sixth most powerful earthquake on record struck Chile. One year after the disaster, a modified version of the PTSD module of the CIDI was administered. Multivariable logistic regression analyses were performed to determine the most robust pre-disaster predictors of post-disaster PTSD.

Results: The majority of our sample was female (75.9%), had a high school/college education (66.9%), and had at least one lifetime pre-disaster disorder (60.9%). After controlling for gender and age, pre-disaster PTSD (OR=1.74; 95%CI=1.15-2.65), Dysthymia (2.23; 1.41-3.53), non-affective Psychosis (2.80; 1.35-5.80), Panic disorder (2.51; 1.42-4.44), Agoraphobia (2.32; 1.27-4.24), Social Phobia (2.02; 1.16-3.52) and Specific Phobia (2.00; 1.45-2.76) were significant predictors of post-disaster PTSD. Compared to those with no disorder, those with pre-disaster PTSD plus 1-2 comorbid disorders (3.29; 1.77-6.12) and pre-disaster PTSD plus 3+ comorbid disorders (3.37; 1.76-6.45) were most at risk for developing post-disaster PTSD.

Conclusions: This is the first study to prospectively examine which pre-disaster psychiatric disorders influence vulnerability to develop PTSD after a major traumatic event.