Does Perceived Social Support Prevent Delayed-Onset Post-Traumatic Stress Disorder (PTSD): A Nested Case-Control Study after the Wenchuan Earthquake

Background: Delayed-onset post-traumatic stress disorder (PTSD) after a catastrophe is a big public health problem. However, good designs for revealing the PTSD among earthquake survivors are rare. This study was the first nested case-control study to explore the relationship between perceived social support and delayed-onset PTSD.  Methods: A nested case-control study was conducted. Baseline (year 2011) and follow-up (year 2018) surveys were carried out to collect data. Those survivors met the criteria of positive symptoms of PTSD from the hardest-hit area were identified as the case group and PTSD-free survivors from the same area matched for age were defined as  the control group, with a ratio of one to four. A conditional logistic regression was applied to evaluate the odds ratio (OR) of variables used in the study.  Results: The unemployed quake survivors had a higher risk of developing delayed-onset PTSD (OR= 4·731, 95% confidence interval = 1·408 to 15·901), while higher perceived social support was a protective factor for suffering from delayed-onset PTSD (OR = 0·172, 95% confidence interval = 0·052 to 0·568). Interpretation: Delayed-onset PTSD after the disaster could not be ignored. Active social support and the provision of stable job would contribute to maintaining the health of earthquake survivors.  Funding: This work was supported by the National Natural Science Foundation of China (grant number 71874115). Declaration of Interests: The authors report no conflicts of interest in this work. Ethics Approval Statement: This research was authorized by the Institutional Review Board (IRB) of West China Hospital of Sichuan University.