Longitudinal course of disaster-related PTSD among a prospective sample of adult Chilean natural disaster survivors.

BACKGROUND

With an increasing number of individuals surviving natural disasters, it is crucial to understand who is most at risk for developing post-traumatic stress disorder (PTSD). The objective of this study was to prospectively examine the role that pre-existing psychopathology plays in developing PTSD after a disaster.

METHODS

This study uses data from a prospective 5-wave longitudinal cohort (years 2003-11) of Chilean adults from 10 health centres ( N  = 1708). At baseline, participants completed the Composite International Diagnostic Interview (CIDI), a comprehensive psychiatric diagnostic instrument. In 2010, the sixth most powerful earthquake on record struck Chile. One year later, a modified version of the PTSD module of the CIDI was administered. Marginal structural logistic regressions with inverse probability censoring weights were constructed to identify pre-disaster psychiatric predictors of post-disaster PTSD.

RESULTS

The majority of participants were female (75.9%) and had a high-school/college education (66.9%). After controlling for pre-disaster PTSD, pre-existing dysthymia [odds ratio (OR) = 2.21; 95% confidence interval (CI) = 1.39-3.52], brief psychotic disorder (OR = 2.67; 95% CI = 1.21-5.90), anxiety disorders (not including PTSD; OR = 1.49; 95% CI = 1.27-1.76), panic disorder (OR = 2.46; 95% CI = 1.37-4.42), agoraphobia (OR = 2.23; 95% CI = 1.22-4.10), social phobia (OR = 1.86; 95% CI = 1.06-3.29), specific phobia (OR = 2.07; 95% CI = 1.50-2.86) and hypochondriasis (OR = 2.10; 95% CI = 1.05-4.18) were predictors of post-disaster PTSD. After controlling for pre-disaster anxiety disorders, dysthymia, and non-affective psychotic disorders, individuals with pre-disaster PTSD (vs those without pre-disaster PTSD) had higher odds of developing post-disaster PTSD (OR = 2.53; 95% CI = 1.37-4.65).

CONCLUSIONS

This is the first Chilean study to demonstrate prospectively that pre-disaster psychiatric disorders, independent of a prior history of other psychiatric disorders, increase the vulnerability to develop PTSD following a major natural disaster.