S1 Data -

Background
There is a lack of studies on trauma exposure and PTSD prevalence in Poland on representative samples. Available data from studies on convenient samples show very high rates of probable PTSD compared with relevant estimates in other countries.
Objective
This study aimed to measure the exposure to self-report traumatic events (PTEs) and to estimate the current rate of prevalence of probable posttraumatic stress disorder (PTSD) in accordance with DSM–5 criteria in a population-based sample of Poles. Additionally, the link between PTSD intensity and level of life satisfaction was investigated.
Method
A representative sample of 1,598 adult Poles was recruited. Probable PTSD was assessed with the Posttraumatic Diagnostic Scale for DSM–5 (PDS–5) and the Satisfaction with Life Scale (SWLS) was also used.
Results
The findings showed that 60.3% of Poles had experienced at least one PTE and 31.1% of those who had been exposed to trauma reported symptoms of PTSD. At the level of the entire sample, the obtained rate for probable PTSD was 18.8%. The traumatic events with the highest probabilities of PTSD symptoms were child abuse and sexual assault. Levels of life satisfaction were significantly lower in the group of participants with probable PTSD.
Conclusions
We found that the current prevalence of probable PTSD in Poland is intriguingly high relative to rates reported in comparable representative samples from other countries across the world. Possible mechanisms are discussed, including a lack of social acknowledgement of WWII and other traumas as well as poor access to trauma-focused care. We hope that this research may inspire more studies investigating cross-national differences in PTSD and trauma exposure.