Ten-Year Follow-Up of Earthquake Survivors: Long-Term Study on the Course of PTSD Following a Natural Disaster.

Objective: Few earthquake survivor studies extend follow-up beyond 2 years, leaving the long-term course of earthquake-related posttraumatic stress disorder (PTSD) unknown. This 10-year survey re-assessed the 1999 İzmit, Turkey, earthquake survivors. Methods: İzmit earthquake survivors (N = 198), previously assessed for PTSD/partial PTSD at 1-3 months and 18-20 months post-earthquake, were evaluated 10 years post-event from January 2009 through December 2010. A PTSD self-test (Turkish translation) used DSM-IV criteria to characterize full PTSD, "stringent partial PTSD," "lenient partial PTSD," or non-PTSD based on symptom type/amount. Results: Full PTSD prevalence decreased from 37% at 1-3 months post-earthquake to 15% at 18-20 months ( P  < .001), remaining relatively stable (12%) at 10 years ( P  = .38). Stringent and lenient partial PTSD decreased between 1-3 months and 18-20 months (from 9% to 3% and from 24% to 12%, respectively; P  < .001), remaining stable at 10 years (5% and 9%, respectively; P  = .43 and P  = .89). PTSD was more prevalent at 1-3 months among those who had a close acquaintance harmed, had been evacuated for long periods (> 1 week), or had more children; this was not observed at 10 years ( P  = .007-.017). Avoidance symptoms 1-3 months post-earthquake were the best predictor for full PTSD at 10 years ( P  < .001). Delayed-onset PTSD was observed in only 2% of participants. Conclusions: Full and partial PTSD decreased over the first 2 years post-trauma, but remained stable at 10 years, suggesting PTSD symptoms at around 2 years remain stable at 10 years. Background characteristics did not predict PTSD long-term course, but avoidance level did. Delayed-onset PTSD was relatively rare.