BACKGROUND: Although only a few people exposed to a traumatic event (TE) develop posttraumatic stress disorder (PTSD), symptoms that do not meet full PTSD criteria are common and often clinically significant. Individuals with these symptoms sometimes have been characterized as having subthreshold PTSD, but no consensus exists on the optimal definition of this term. Data from a large cross-national epidemiologic survey are used in this study to provide a principled basis for such a definition. METHODS: The World Health Organization World Mental Health Surveys administered fully structured psychiatric diagnostic interviews to community samples in 13 countries containing assessments of PTSD associated with randomly selected TEs. Focusing on the 23,936 respondents reporting lifetime TE exposure, associations of approximated DSM-5 PTSD symptom profiles with six outcomes (distress-impairment, suicidality, comorbid fear-distress disorders, PTSD symptom duration) were examined to investigate implications of different subthreshold definitions. RESULTS: Although consistently highest outcomes for distress-impairment, suicidality, comorbidity, and PTSD symptom duration were observed among the 3.0% of respondents with DSM-5 PTSD rather than other symptom profiles, the additional 3.6% of respondents meeting two or three of DSM-5 criteria B-E also had significantly elevated scores for most outcomes. The proportion of cases with threshold versus subthreshold PTSD varied depending on TE type, with threshold PTSD more common following interpersonal violence and subthreshold PTSD more common following events happening to loved ones. CONCLUSIONS: Subthreshold DSM-5 PTSD is most usefully defined as meeting two or three of DSM-5 criteria B-E. Use of a consistent definition is critical to advance understanding of the prevalence, predictors, and clinical significance of subthreshold PTSD.

This work was supported by the National Institute of Mental Health (Grant Nos. R01 MH070884 and R01 MH093612-01), the John D. and Catherine T. MacArthur Foundation, the Pfizer Foundation, the United States Public Health Service (Grant Nos. R13-MH066849, R01-MH069864, and R01 DA016558), the Fogarty International Center (Grant No. FIRCA R03-TW006481).The São Paulo Megacity Mental Health Survey is supported by the State of São Paulo Research Foundation Thematic Project Grant No. 03/00204-3. The European Study of the Epidemiology of Mental Disorders (ESEMeD) project is funded by the European Commission (Contracts QLG5-1999-01042, Health and Consumer Affairs (SANCO) 2004123, and Executive Agency for Health and Consumers (EACH) 20081308); the Piedmont Region, Italy; Fondo de Investigación Sanitaria, Instituto de Salud Carlos III, Spain (Grant No. Fund for Health of Spain (FIS) 00/0028); Ministerio de Ciencia y Tecnología, Spain (Grant No. SAF 2000-158-CE); Departament de Salut, Generalitat de Catalunya, Spain; Instituto de Salud Carlos III (Grant Nos. Networked Biomedical Research Centres (CIBER) CB06/02/0046 and Cooperative Health Research Thematic Networks (RETICS) RD06/0011 REM-TAP).The World Mental Health Japan Survey is supported by the Grant for Research on Psychiatric and Neurological Diseases and Mental Health (Grant Nos. H13-SHOGAI-023, H14-TOKUBETSU-026, and H16-KOKORO-013) from the Japan Ministry of Health, Labour and Welfare.The Mexican National Comorbidity Survey is supported by The National Institute of Psychiatry Ramon de la Fuente (Grant No. INPRFMDIES 4280) and by the National Council on Science and Technology (Grant No. CONACyT-G30544-H).The U.S. National Comorbidity Survey Replication is supported by the National Institute of Mental Health (Grant No. U01-MH60220) with supplemental support the Robert Wood Johnson Foundation (Grant No. 044708).