Background Although only a minority of people exposed to a traumatic event (TE) develops PTSD symptoms not meeting full PTSD criteria are common and often clinically significant. symptom duration) were examined to investigate implications of different sub-threshold definitions. Results Although consistently highest distress-impairment suicidality comorbidity and symptom duration were observed among the 3.0% of respondents with DSM-5 PTSD than other symptom profiles the additional 3.6% of respondents meeting two or three of DSM-5 Criteria BE also had significantly elevated scores for most outcomes. The proportion of cases with threshold versus sub-threshold PTSD varied depending on TE type with threshold PTSD more common following interpersonal violence and sub-threshold PTSD more common following events happening to loved ones. Conclusions Sub-threshold DSM-5 PTSD is most usefully defined as meeting two or three of the DSM-5 Criteria B-E. Use of a consistent definition Losmapimod is critical to advance understanding of the prevalence predictors and clinical significance of CAP1 sub-threshold PTSD. TEs (31). The 23 936 respondents in these surveys reporting lifetime TE exposure are the focus of analysis. The 13 countries include eight classified by the World Bank (32) as high income (Belgium Germany Italy Japan Netherlands New Zealand Spain United States) four upper-middle income (S?o Paulo in Brazil Bulgaria Mexico Romania) and one lower-middle income (Colombia). Most surveys were based on nationally representative household samples the exceptions being surveys of all urbanized areas in Colombia and Mexico and of specific Metropolitan areas in Brazil (S?o Paulo) Losmapimod and a series of cities in Japan. Response rates ranged from 55.1 % (Japan) to 87.7% (Colombia). The weighted (by sample size) mean response rate across surveys was 70.3%. More detailed sample descriptions are presented elsewhere (33). Interviews were administered face-to-face in respondent homes after obtaining informed consent using procedures approved by local Institutional Review Boards. The interview schedule was developed in English and translated into other languages using a standardized WHO translation back-translation and harmonization protocol (34). Interviews were in two parts. Part I administered to all respondents assessed core DSM-IV mental disorders (n=67 652 respondents across all 13 surveys). Part II assessed additional disorders and correlates. Questions about TEs and PTSD were included in Part II which was administered to 100% of Part I respondents who met lifetime criteria for any Part I disorder and Losmapimod a probability subsample of other Part I respondents (n=34 321 across all 13 surveys). Part II respondents with no Part I disorder were up-weighted to adjust for under-sampling resulting in Part II weighted prevalence estimations being identical to Part I estimates. Additional weights modified for differential within Losmapimod and between household selection and deviations between sample and populace demographic-geographic distributions. More details about WMH sample design and weighting are offered elsewhere (33). Steps Traumatic events (TEs) WMH assessed lifetime exposure to 29 TEs including seven war-related (e.g. combatant civilian in war zone) five types of physical assault (e.g. beaten by caregiver as a child mugged) three types of sexual assault Losmapimod (e.g. stalked attempted rape rape) six including risks to physical integrity excluding violence (e.g. life-threatening incidents natural disasters) five including threats to loved ones (e.g. life-threatening illness/injury) and traumatic death of loved one. Two additional open-ended questions asked about TEs not included on the list and TEs respondents did not wish to describe concretely. Respondents were probed about quantity of lifetime occurrences and age at first event of each reported TE type. PTSD Mental disorders were assessed with the Composite International Diagnostic Interview (CIDI) (35) a fully-structured lay-administered interview yielding DSM-IV diagnoses. PTSD was assessed in relation to one lifetime TE for each respondent in order to produce a population-level representative sample of TEs (35). Each random TE was weighted by its probability of selection for the respondent producing a weighted dataset representative of all lifetime TEs occurring to all respondents. The chance of some TEs getting element of linked injury clusters (e.g. a electric motor.