Quality Checklist for Prevalence Meta-Analysis

Checklist to assess each study’s quality.

Score 0, 1 or 2 for each question on each study.

Assessed by: ______________

Population

Were participants and setting well described?

(2)Information regarding the characteristics (age, gender, ethnicity) of the sample and trauma variables (type, severity, duration) are well described with the setting well reported (health setting, country, geography)

(1)Some information regarding participants characteristics and trauma variables are reported, with limited information on the setting

(0)Sample characteristics, trauma variables and setting information are not reported in any detail

Was participation rate of those eligible at least 50%?

(2)More than 50% of those eligible to participate took part

(1)Less than 50% of those eligible to participate took part

(0)The number of eligible potential participants was not reported

Were reasons for non-response described?

(2)Reasons for non-response were described with the number of those participants not responding reported

(1)Reasons were described for non-responders but no numbers provided OR Numbers of non-responders are reported but with no reasons

(0)Non-response rates were not reported in the study

Was the sample representative – were there differences between those participants taking part and those not?

(2)There were no significant differences in demographics or trauma variables between those participating and those not

(1)Reported significant differences between those participating and those not

(0)Differences between participants and those not taking part were not reported

Were participants recruited in an appropriate way?

(2)Consecutive or random sampling was used to recruit potential participants in person by the research team

(1)Consecutive or random sampling was used to recruit potential participants via letter or phone call

(0)Recruitment procedures were not reported in the study

Were inclusion and exclusion criteria explicit and appropriate?

(2)Inclusion and exclusion criteria were reported in detail

(0)Inclusion and exclusion criteria were not reported

Supplement 2

Reference list of excluded articles and justifications

Articles in which full texts were examined and then excluded from the meta-analysis (k=119)

Subheadings detailing the reason for exclusion are provided

Does not meet age criteria (k=30)

Almqvist, K., & Broberg, A. G. (1999). Mental health and social adjustment in young refugee children y 3½ years after their arrival in Sweden. Journal of the American Academy of Child & Adolescent Psychiatry, 38(6), 723-730. https://doi.org/10.1097/00004583-199906000-00020Deblinger, E., Taub, B., Maedel, A. B., Lippmann, J., & Stauffer, L. B. (1998). Psychosocial factors predicting parent reported symptomatology in sexually abused children. Journal of Child Sexual Abuse, 6(4), 35-49. https://doi.org/10.1300/j070v06n04_03Ellis, A., Stores, G., & Mayou, R. (1998). Psychological consequences of road traffic accidents in children. European child & adolescent psychiatry, 7(2), 61-68. https://doi.org/10.1007/s007870050048Endo, T., Shioiri, T., & Someya, T. (2009). Post‐traumatic symptoms among the children and adolescents 2 years after the 2004 Niigata–Chuetsu earthquake in Japan. Psychiatry and clinical neurosciences, 63(2), 253-253. https://doi.org/10.1111/j.1440-1819.2008.01914.xFamularo, R., Kinscherff, R., & Fenton, T. (1992). Psychiatric diagnoses of maltreated children: preliminary findings. Journal of the American Academy of Child & Adolescent Psychiatry, 31(5), 863-867. https://doi.org/10.1097/00004583-199209000-00013Field, T., Seligman, S., Scafidi, F., & Schanberg, S. (1996). Alleviating posttraumatic stress in children following Hurricane Andrew. Journal of applied developmental psychology, 17(1), 37-50. https://doi.org/10.1016/s0193-3973(96)90004-0Fujiwara, T., Yagi, J., Homma, H., Mashiko, H., Nagao, K., & Okuyama, M. (2017). Symptoms of post-traumatic stress disorder among young children 2 years after the Great East Japan Earthquake. Disaster medicine and public health preparedness, 11(2), 207-215. https://doi.org/10.1017/dmp.2016.101Garfin, D. R., Silver, R. C., Gil-Rivas, V., Guzmán, J., Murphy, J. M., Cova, F., ... & Guzmán, M. P. (2014). Children’s reactions to the 2010 Chilean earthquake: The role of trauma exposure, family context, and school-based mental health programming. Psychological Trauma: Theory, Research, Practice, and Policy, 6(5), 563. https://doi.org/10.1037/a0036584

Grasso, D., Boonsiri, J., Lipschitz, D., Guyer, A., Houshyar, S., Douglas-Palumberi, H., ... & Kaufman, J. (2009). Posttraumatic stress disorder: The missed diagnosis. Child Welfare, 88(4), 157.

Green, B.L., Korol. M., Grace, M.C., Vary, M.G., Leonard, A.C., Gleser, G.C., & Smitson-Cohen, S. (1991). Children and disaster: Age, gender, and parental effects on PTSD symptoms. Journal of the American Academy of Child & Adolescent Psychiatry, 30(6), 945-951. https://doi.org/10.1097/00004583-199111000-00012Husain, S. A., Allwood, M. A., & Bell, D. J. (2008). The relationship between PTSD symptoms and attention problems in children exposed to the Bosnian war. Journal of Emotional and Behavioral Disorders, 16(1), 52-62. https://doi.org/10.1177/1063426607310847Kessler, R. C., Duncan, G. J., Gennetian, L. A., Katz, L. F., Kling, J. R., Sampson, N. A., ... & Ludwig, J. (2014). Associations of housing mobility interventions for children in high-poverty neighborhoods with subsequent mental disorders during adolescence. Jama, 311(9), 937-947. https://doi.org/10.1001/jama.2014.607Kocijan-Hercigonja, D., Rijavec, M., Jones, W. P., & Remeta, D. (1996). Psychologic problems of children wounded during the war in Croatia. Nordic Journal of Psychiatry, 50(6), 451-456. https://doi.org/10.3109/08039489609082513Lamers-Winkelman, F., Willemen, A. M., & Visser, M. (2012). Adverse childhood experiences of referred children exposed to intimate partner violence: Consequences for their wellbeing. Child abuse & neglect, 36(2), 166-179. https://doi.org/10.1016/j.chiabu.2011.07.006Lehmann, P., & Elliston, E. J. (2001). Traumatic responding in children exposed to domestic violence: A cross-cultural study. Journal of Ethnic and Cultural Diversity in Social Work, 10(4), 81-102. https://doi.org/10.1300/j051v10n04_05Nader, K., Pynoos, R., Fairbanks, L., & Frederick, C. (1990). Children's PTSD reactions one year after a sniper attack at their school. The American journal of psychiatry. https://doi.org/10.1176/ajp.147.11.1526Şahin, N. H., Batıgün, A. D., & Yılmaz, B. (2007). Psychological symptoms of Turkish children and adolescents after the 1999 earthquake: Exposure, gender, location, and time duration. Journal of Traumatic Stress: Official Publication of The International Society for Traumatic Stress Studies, 20(3), 335-345. https://doi.org/10.1002/jts.20217Saltzman, K. M., Weems, C. F., & Carrion, V. G. (2006). IQ and posttraumatic stress symptoms in children exposed to interpersonal violence. Child Psychiatry and Human Development, 36(3), 261-272. https://doi.org/10.1007/s10578-005-0002-5Santiago, C. D., Raviv, T., Ros, A. M., Brewer, S. K., Distel, L. M., Torres, S. A., ... & Langley, A. K. (2018). Implementing the Bounce Back trauma intervention in urban elementary schools: A real-world replication trial. School Psychology Quarterly, 33(1), 1-9. https://doi.org/10.1037/spq0000229Schilpzand, E. J., Sciberras, E., Alisic, E., Efron, D., Hazell, P., Jongeling, B., ... & Nicholson, J. M. (2018). Trauma exposure in children with and without ADHD: prevalence and functional impairment in a community-based study of 6–8-year-old Australian children. European child & adolescent psychiatry, 27(6), 811-819. https://doi.org/10.1007/s00787-017-1067-yShears, D., Nadel, S., Gledhill, J., Gordon, F., & Garralda, M. E. (2007). Psychiatric adjustment in the year after meningococcal disease in childhood. Journal of the American Academy of Child & Adolescent Psychiatry, 46(1), 76-82. https://doi.org/10.1097/01.chi.0000242234.83140.56Sim, L., Friedrich, W. N., Davies, W. H., Trentham, B., Lengua, L., & Pithers, W. (2005). The Child Behavior Checklist as an indicator of posttraumatic stress disorder and dissociation in normative, psychiatric, and sexually abused children. Journal of Traumatic Stress: Official Publication of The International Society for Traumatic Stress Studies, 18(6), 697-705. https://doi.org/10.1002/jts.20078Soykoek, S., Mall, V., Nehring, I., Henningsen, P., & Aberl, S. (2017). Post-traumatic stress disorder in Syrian children of a German refugee camp. The Lancet, 389(10072), 903-904. https://doi.org/10.1016/s0140-6736(17)30595-0Vaage, A. B., Garløv, I., Hauff, E., & Thomsen, P. H. (2007). Psychiatric symptoms and service utilization among refugee children referred to a child psychiatry department: a retrospective comparative case note study. Transcultural psychiatry, 44(3), 440-458. https://doi.org/10.1177/1363461507081641Wiguna, T., Guerrero, A. P., Kaligis, F., & Khamelia, M. (2010). Psychiatric morbidity among children in North Aceh district (Indonesia) exposed to the 26 December 2004 tsunami. Asia‐Pacific Psychiatry, 2(3), 151-155. https://doi.org/10.1111/j.1758-5872.2010.00079.xWu, F., Meng, W. Y., Hao, C. Z., Zhu, L. L., Chen, D. Q., Lin, L. Y., & Wen, H. (2016). Analysis of posttraumatic stress disorder in children with road traffic injury in Wenzhou, China. Traffic injury prevention, 17(2), 159-163. https://doi.org/10.1080/15389588.2015.1050719

Does not meet study design criteria (k=4)

Abd-Elshafy, S. K., Khalaf, G. S., Abo-Kerisha, M. Z., Ahmed, N. T., El-Aziz, M. A. A., & Mohamed, M. A. (2015). Not all sounds have negative effects on children undergoing cardiac surgery. Journal of cardiothoracic and vascular anesthesia, 29(5), 1277-1284. https://doi.org/10.1053/j.jvca.2015.01.005Briggs‐Gowan, M. J., Grasso, D., Bar‐Haim, Y., Voss, J., McCarthy, K. J., Pine, D. S., & Wakschlag, L. S. (2016). Attention bias in the developmental unfolding of post‐traumatic stress symptoms in young children at risk. Journal of child psychology and psychiatry, 57(9), 1083-1091. https://doi.org/10.1111/jcpp.12577Horn, S. R., Miller-Graff, L. E., Galano, M. M., & Graham-Bermann, S. A. (2017). Posttraumatic stress disorder in children exposed to intimate partner violence: the clinical picture of physiological arousal symptoms. Child care in practice, 23(1), 90-103. https://doi.org/10.1080/13575279.2015.1126229Scheeringa, M. S. (2008). Developmental considerations for diagnosing PTSD and acute stress disorder in preschool and school-age children. The American Journal of Psychiatry, 165 (10), 1237-1239. https://doi.org/10.1176/appi.ajp.2008.08070974

Indirect trauma (k=2)

Abbo, C., Kinyanda, E., Kizza, R. B., Levin, J., Ndyanabangi, S., & Stein, D. J. (2013). Prevalence, comorbidity and predictors of anxiety disorders in children and adolescents in rural north-eastern Uganda. Child and adolescent psychiatry and mental health, 7(1), 21. https://doi.org/10.1186/1753-2000-7-21Saylor, C. F., Cowart, B. L., Lipovsky, J. A., Jackson, C., & Finch Jr, A. J. (2003). Media exposure to September 11: Elementary school students' experiences and posttraumatic symptoms. American Behavioral Scientist, 46(12), 1622-1642. https://doi.org/10.1177/0002764203254619

Not measuring pre-school PTSD (k=12)

Al-Jawadi, A. A., & Abdul-Rhman, S. (2007). Prevalence of childhood and early adolescence mental disorders among children attending primary health care centers in Mosul, Iraq: a cross-sectional study. BMC public health, 7(1), 274. https://doi.org/10.1186/1471-2458-7-274Briere, J., Johnson, K., Bissada, A., Damon, L., Crouch, J., Gil, E., ... & Ernst, V. (2001). The Trauma Symptom Checklist for Young Children (TSCYC): Reliability and association with abuse exposure in a multi-site study. Child abuse & neglect, 25(8), 1001-1014. https://doi.org/10.1016/s0145-2134(01)00253-8De Young, A. C., Hendrikz, J., Kenardy, J. A., Cobham, V. E., & Kimble, R. M. (2014). Prospective evaluation of parent distress following pediatric burns and identification of risk factors for young child and parent posttraumatic stress disorder. Journal of Child and Adolescent Psychopharmacology, 24(1), 9-17. https://doi.org/10.1089/cap.2013.0066Endo, T., Shioiri, T., Someya, T., Toyabe, S., & Akazawa, K. (2007). Parental mental health affects behavioral changes in children following a devastating disaster: a community survey after the 2004 Niigata-Chuetsu earthquake. General hospital psychiatry, 29(2), 175-176. https://doi.org/10.1016/j.genhosppsych.2006.09.006Lieberman, A. F., Van Horn, P., & Ippen, C. G. (2005). Toward evidence-based treatment: Child-parent psychotherapy with preschoolers exposed to marital violence. Journal of the American Academy of Child & Adolescent Psychiatry, 44(12), 1241-1248. https://doi.org/10.1097/01.chi.0000181047.59702.58Milburn, N. L., Lynch, M., & Jackson, J. (2008). Early identification of mental health needs for children in care: A therapeutic assessment programme for statutory clients of child protection. Clinical child psychology and psychiatry, 13(1), 31-47. https://doi.org/10.1177/1359104507086339Schrag, N. M., McKeown, R. E., Jackson, K. L., Cuffe, S. P., & Neuberg, R. W. (2008). Stress‐related mental disorders in childhood cancer survivors. Pediatric blood & cancer, 50(1), 98-103. https://doi.org/10.1002/pbc.21285Sprang, G., Staton‐Tindall, M., & Clark, J. (2008). Trauma exposure and the drug endangered child. Journal of Traumatic Stress: Official Publication of The International Society for Traumatic Stress Studies, 21(3), 333-339. https://doi.org/10.1002/jts.20330Stoddard, F. J., Saxe, G., Ronfeldt, H., Drake, J. E., Burns, J., Edgren, C., & Sheridan, R. (2006). Acute stress symptoms in young children with burns. Journal of the American Academy of Child & Adolescent Psychiatry, 45(1), 87-93. https://doi.org/10.1097/01.chi.0000184934.71917.3aStoddard Jr, F. J., Sorrentino, E. A., Ceranoglu, T. A., Saxe, G., Murphy, J. M., Drake, J. E., ... & Sheridan, R. L. (2009). Preliminary evidence for the effects of morphine on posttraumatic stress disorder symptoms in one-to four-year-olds with burns. Journal of Burn Care & Research, 30(5), 836-843. https://doi.org/10.1097/bcr.0b013e3181b48102

Clinical or PTSD sample (k=17)

Als, L. C., Nadel, S., Cooper, M., Vickers, B., & Garralda, M. E. (2015). A supported psychoeducational intervention to improve family mental health following discharge from paediatric intensive care: feasibility and pilot randomised controlled trial. BMJ open, 5(12), e009581. https://doi.org/10.1136/bmjopen-2015-009581De Bellis, M. D., Hooper, S. R., Spratt, E. G., & Woolley, D. P. (2009). Neuropsychological findings in childhood neglect and their relationships to pediatric PTSD. Journal of the International Neuropsychological Society, 15(6), 868-878. https://doi.org/10.1017/s1355617709990464Deblinger, E., Mannarino, A. P., Cohen, J. A., Runyon, M. K., & Steer, R. A. (2011). Trauma‐focused cognitive behavioral therapy for children: impact of the trauma narrative and treatment length. Depression and anxiety, 28(1), 67-75. https://doi.org/10.1002/da.20744Dehon, C., & Scheeringa, M. S. (2006). Screening for preschool posttraumatic stress disorder with the Child Behavior Checklist. Journal of Pediatric Psychology, 31(4), 431-435. https://doi.org/10.1093/jpepsy/jsj006Hulette, A. C., Freyd, J. J., Pears, K. C., Kim, H. K., Fisher, P. A., & Becker-Blease, K. A. (2008). Dissociation and posttraumatic symptoms in maltreated preschool children. Journal of child & adolescent trauma, 1(2), 93-108. https://doi.org/10.1080/19361520802083980Ippen, C. G., Harris, W. W., Van Horn, P., & Lieberman, A. F. (2011). Traumatic and stressful events in early childhood: Can treatment help those at highest risk?. Child abuse & neglect, 35(7), 504-513. https://doi.org/10.1016/j.chiabu.2011.03.009

Karacetin, G., Demir, T., Baghaki, S., Cetinkale, O., & Elagoz Yuksel, M. (2014). Psychiatric disorders and their association with burn-related factors in children with burn injury. Turkish Journal of Trauma and Emergency Surgery, 20(3), 176-180. https://doi.org/10.5505/tjtes.2014.49033

Kiser, L. J., Ackerman, B. J., Brown, E., Edwards, N. B., McColgan, E. D. G. A. R., Pugh, R., & Pruitt, D. B. (1988). Post-traumatic stress disorder in young children: A reaction to purported sexual abuse. Journal of the American Academy of Child & Adolescent Psychiatry, 27(5), 645-649. https://doi.org/10.1097/00004583-198809000-00023Kramer, D. N., & Landolt, M. A. (2014). Early psychological intervention in accidentally injured children ages 2–16: A randomized controlled trial. European journal of psychotraumatology, 5(1), 24402. https://doi.org/10.3402/ejpt.v5.24402Kramer, D. N., Hertli, M. B., & Landolt, M. A. (2013). Evaluation of an early risk screener for PTSD in preschool children after accidental injury. Pediatrics, 132(4), e945-e951. https://doi.org/10.1542/peds.2013-0713Scheeringa, M. S., Peebles, C. D., Cook, C. A., & Zeanah, C. H. (2001). Toward establishing procedural, criterion, and discriminant validity for PTSD in early childhood. Journal of the American Academy of Child & Adolescent Psychiatry, 40(1), 52-60. https://doi.org/10.1097/00004583-200101000-00016Scheeringa, M. S., Zeanah, C. H., Myers, L., & Putnam, F. W. (2003). New findings on alternative criteria for PTSD in preschool children. Journal of the American Academy of Child & Adolescent Psychiatry, 42(5), 561-570. https://doi.org/10.1097/01.chi.0000046822.95464.14Scheeringa, M. S., Zeanah, C. H., Myers, L., & Putnam, F. W. (2005). Predictive validity in a prospective follow-up of PTSD in preschool children. Journal of the American Academy of Child & Adolescent Psychiatry, 44(9), 899-906. https://doi.org/10.1097/01.chi.0000169013.81536.71Scheeringa, M. S., Myers, L., Putnam, F. W., & Zeanah, C. H. (2015). Maternal factors as moderators or mediators of PTSD symptoms in very young children: a two-year prospective study. Journal of Family Violence, 30(5), 633-642. https://doi.org/10.1007/s10896-015-9695-9Seng, J. S., Graham-Bermann, S. A., Clark, M. K., McCarthy, A. M., & Ronis, D. L. (2005). Posttraumatic stress disorder and physical comorbidity among female children and adolescents: results from service-use data. Pediatrics, 116(6), e767-e776. https://doi.org/10.1542/peds.2005-0608Smith, T. J., Lindsey, R. A., Bohora, S., & Silovsky, J. F. (2019). Predictors of intrusive sexual behaviors in preschool-aged children. The Journal of Sex Research, 56(2), 229-238. https://doi.org/10.1080/00224499.2018.1447639

Studies duplicating same data sample (k=6)

Cohen, E., Chazan, S., Lerner, M., & Maimon, E. (2010). Posttraumatic play in young children exposed to terrorism: An empirical study. Infant Mental Health Journal: Official Publication of the World Association for Infant Mental Health, 31(2), 159-181. https://doi.org/10.1002/imhj.20250De Young, A. C., Kenardy, J. A., Cobham, V. E., & Kimble, R. (2012). Prevalence, comorbidity and course of trauma reactions in young burn‐injured children. Journal of Child Psychology and Psychiatry, 53(1), 56-63. https://doi.org/10.1111/j.1469-7610.2011.02431.xMeiser-Stedman, R., Smith, P., Yule, W., Glucksman, E., & Dalgleish, T. (2017). Posttraumatic stress disorder in young children three years post-trauma: Prevalence and longitudinal predictors. The Journal of clinical psychiatry, 78(3), 334-339. https://doi.org/10.4088/jcp.15m10002Scheeringa, M. S., Zeanah, C. H., Myers, L., & Putnam, F. W. (2003). New findings on alternative criteria for PTSD in preschool children. Journal of the American Academy of Child & Adolescent Psychiatry, 42(5), 561-570. https://doi.org/10.1097/01.CHI.0000046822.95464.14Scheeringa, M. S., & Zeanah, C. H. (2008). Reconsideration of harm's way: Onsets and comorbidity patterns of disorders in preschool children and their caregivers following Hurricane Katrina. Journal of Clinical Child & Adolescent Psychology, 37(3), 508-518. https://doi.org/10.1080/15374410802148178Scheeringa, M. S. (2019). Development of a brief screen for symptoms of posttraumatic stress disorder in young children: the Young Child PTSD Screen. Journal of Developmental & Behavioral Pediatrics, 40(2), 105-111. https://doi.org/10.1097/dbp.0000000000000639

Data does not describe prevalence (k=4)

DeVoe, E. R., Klein, T. P., Bannon Jr, W., & Miranda-Julian, C. (2011). Young children in the aftermath of the World Trade Center attacks. Psychological Trauma: Theory, Research, Practice, and Policy, 3(1), 1-11. https://doi.org/10.1037/a0020567Drake, J. E., Stoddard Jr, F. J., Murphy, J. M., Ronfeldt, H., Snidman, N., Kagan, J., ... & Sheridan, R. (2006). Trauma severity influences acute stress in young burned children. Journal of burn care & research, 27(2), 174-182. https://doi.org/10.1097/01.bcr.0000202618.51001.69Grasso, D. J., Ford, J. D., & Briggs-Gowan, M. J. (2013). Early life trauma exposure and stress sensitivity in young children. Journal of pediatric psychology, 38(1), 94-103. https://doi.org/10.1093/jpepsy/jss101Stoddard, F. J., Ronfeldt, H., Kagan, J., Drake, J. E., Snidman, N., Murphy, J. M., ... & Sheridan, R. L. (2006). Young burned children: the course of acute stress and physiological and behavioral responses. American journal of psychiatry, 163(6), 1084-1090. https://doi.org/10.1176/ajp.2006.163.6.1084

Questionnaire based (k=39)

Als, L. C., Picouto, M. D., O’Donnell, K. J., Nadel, S., Cooper, M., Pierce, C. M., ... & Garralda, M. E. (2017). Stress hormones and posttraumatic stress symptoms following paediatric critical illness: an exploratory study. European child & adolescent psychiatry, 26(5), 511-519. https://doi.org/10.1007/s00787-016-0933-3Ari, A. B., Peri, T., Margalit, D., Galili-Weisstub, E., Udassin, R., & Benarroch, F. (2018). Surgical procedures and pediatric medical traumatic stress (PMTS) syndrome: Assessment and future directions. Journal of pediatric surgery, 53(8), 1526-1531. https://doi.org/10.1016/j.jpedsurg.2017.10.043Azarian, A., Miller, T. W., & Skriptchenko-Gregorian, V. (1996). Baseline assessment of children traumatized by the Armenian earthquake. Child psychiatry and human development, 27(1), 29-41. https://doi.org/10.1007/bf02353444Bogat, G. A., DeJonghe, E., Levendosky, A. A., Davidson, W. S., & von Eye, A. (2006). Trauma symptoms among infants exposed to intimate partner violence. Child abuse & neglect, 30(2), 109-125. https://doi.org/10.1016/j.chiabu.2005.09.002Breton, J. J., Valla, J. P., & Lambert, J. (1993). Industrial disaster and mental health of children and their parents. Journal of the American Academy of Child & Adolescent Psychiatry, 32(2), 438-445. https://doi.org/10.1097/00004583-199303000-00028Broekman, B. F., Olff, M., Tan, F. M., Schreuder, B. J., Fokkens, W., & Boer, F. (2010). The psychological impact of an adenoidectomy and adenotonsillectomy on young children. International journal of pediatric otorhinolaryngology, 74(1), 37-42. https://doi.org/10.1016/j.ijporl.2009.10.005Chae, Y., Goodman, G. S., Eisen, M. L., & Qin, J. (2011). Event memory and suggestibility in abused and neglected children: Trauma-related psychopathology and cognitive functioning. Journal of experimental child psychology, 110(4), 520-538. https://doi.org/10.1016/j.jecp.2011.05.006Fairbrother, G., Stuber, J., Galea, S., Fleischman, A. R., & Pfefferbaum, B. (2003). Posttraumatic stress reactions in New York City children after the September 11, 2001, terrorist attacks. Ambulatory Pediatrics, 3(6), 304-311 https://doi.org/10.1367/1539-4409(2003)003<0304:psriny>2.0.co;2Fujiwara, T., Mizuki, R., Miki, T., & Chemtob, C. (2015). Association between facial expression and PTSD symptoms among young children exposed to the Great East Japan Earthquake: a pilot study. Frontiers in psychology, 6, 1534. https://doi.org/10.3389/fpsyg.2015.01534Garralda, M. E., Gledhill, J., Nadel, S., Neasham, D., O'Connor, M., & Shears, D. (2009). Longer-term psychiatric adjustment of children and parents after meningococcal disease. Pediatric Critical Care Medicine, 10(6), 675-680. https://doi.org/10.1097/pcc.0b013e3181ae785aGil‐Rivas, V., & Kilmer, R. P. (2013). Children's adjustment following Hurricane Katrina: The role of primary caregivers. American journal of orthopsychiatry, 83(2-3), 413-421. https://doi.org/10.1111/ajop.12016Hagan, M. J., Sulik, M. J., & Lieberman, A. F. (2016). Traumatic life events and psychopathology in a high risk, ethnically diverse sample of young children: A person-centered approach. Journal of abnormal child psychology, 44(5), 833-844. https://doi.org/10.1007/s10802-015-0078-8Hickman, L. J., Jaycox, L. H., Setodji, C. M., Kofner, A., Schultz, D., Barnes-Proby, D., & Harris, R. (2013). How much does “how much” matter? Assessing the relationship between children’s lifetime exposure to violence and trauma symptoms, behavior problems, and parenting stress. Journal of interpersonal violence, 28(6), 1338-1362. https://doi.org/10.1177/0886260512468239Jonkman, C. S., Schuengel, C., Lindeboom, R., Oosterman, M., Boer, F., & Lindauer, R. J. (2013). The effectiveness of Multidimensional Treatment Foster Care for Preschoolers (MTFC-P) for young children with severe behavioral disturbances: study protocol for a randomized controlled trial. Trials, 14(1), 197. https://doi.org/10.1186/1745-6215-14-197Kaplow, J. B., Howell, K. H., & Layne, C. M. (2014). Do circumstances of the death matter? Identifying socioenvironmental risks for grief‐related psychopathology in bereaved youth. Journal of Traumatic Stress, 27(1), 42-49. https://doi.org/10.1002/jts.21877Kaufman‐Shriqui, V., Werbeloff, N., Faroy, M., Meiri, G., Shahar, D. R., Fraser, D., ... & Pietrzak, R. H. (2013). Posttraumatic stress disorder among preschoolers exposed to ongoing missile attacks in the Gaza war. Depression and anxiety, 30(5), 425-431. https://doi.org/10.1002/da.22121Kisiel, C. L., Fehrenbach, T., Torgersen, E., Stolbach, B., McClelland, G., Griffin, G., & Burkman, K. (2014). Constellations of interpersonal trauma and symptoms in child welfare: Implications for a developmental trauma framework. Journal of Family Violence, 29(1), 1-14. https://doi.org/10.1007/s10896-013-9559-0Laor, N., Wolmer, L., Mayes, L. C., Gershon, A., Weizman, R., & Cohen, D. J. (1997). Israeli preschool children under Scuds: a 30-month follow-up. Journal of the American Academy of Child & Adolescent Psychiatry, 36(3), 349-356. https://doi.org/10.1097/00004583-199703000-00013Lester, P., Stein, J. A., Saltzman, W., Woodward, K., MacDermid, S. W., Milburn, N., ... & Beardslee, W. (2013). Psychological health of military children: Longitudinal evaluation of a family-centered prevention program to enhance family resilience. Military medicine, 178(8), 838-845. https://doi.org/10.7205/milmed-d-12-00502Levendosky, A. A., Huth-Bocks, A. C., Semel, M. A., & Shapiro, D. L. (2002). Trauma symptoms in preschool-age children exposed to domestic violence. Journal of interpersonal Violence, 17(2), 150-164. https://doi.org/10.1177/0886260502017002003Magwaza, A. S., Killian, B. J., Petersen, I., & Pillay, Y. (1993). The effects of chronic violence on preschool children living in South African townships. Child Abuse & Neglect, 17(6), 795-803. https://doi.org/10.1016/s0145-2134(08)80010-5Milot, T., Éthier, L. S., St-Laurent, D., & Provost, M. A. (2010). The role of trauma symptoms in the development of behavioral problems in maltreated preschoolers. Child abuse & neglect, 34(4), 225-234. https://doi.org/10.1016/j.chiabu.2009.07.006Mongillo, E. A., Briggs-Gowan, M., Ford, J. D., & Carter, A. S. (2009). Impact of traumatic life events in a community sample of toddlers. Journal of Abnormal Child Psychology, 37(4), 455-468. https://doi.org/10.1007/s10802-008-9283-z

Nader, K., Stuber, M., & Pynoos, R. (1991). Posttraumatic stress reactions in preschool children with catastrophic illness: Assessment needs. Comprehensive Mental Health Care, 1(3), 223-239.

Nilsson, D., Gustafsson, P. E., & Svedin, C. G. (2012). The psychometric properties of the Trauma Symptom Checklist for Young Children in a sample of Swedish children. European journal of psychotraumatology, 3(1), 18505. https://doi.org/10.3402/ejpt.v3i0.18505Nuttman-Shwartz, O. (2017). Children and adolescents facing a continuous security threat: Aggressive behavior and post-traumatic stress symptoms. Child Abuse & Neglect, 69, 29-39. https://doi.org/10.1016/j.chiabu.2017.04.008Pernebo, K., Fridell, M., & Almqvist, K. (2018). Outcomes of psychotherapeutic and psychoeducative group interventions for children exposed to intimate partner violence. Child abuse & neglect, 79, 213-223. https://doi.org/10.1016/j.chiabu.2018.02.014

Piyasil, V., Ketumarn, P., Prubrukarn, R., Pacharakaew, S., Dumrongphol, H., Rungsri, S., ... & Theerawongseree, S. (2008). Psychiatric disorders in children at one year after the tsunami disaster in Thailand. J Med Assoc Thai, 91(Suppl 3), S15-S20.

Rivara, F. P., McCarty, C. A., Shandro, J., Wang, J., & Zatzick, D. (2014). Parental injury and psychological health of children. Pediatrics, 134(1), e88-e97. https://doi.org/10.1542/peds.2013-3273Rossman, B. R., Bingham, R. D., & Emde, R. N. (1997). Symptomatology and adaptive functioning for children exposed to normative stressors, dog attack, and parental violence. Journal of the American Academy of Child & Adolescent Psychiatry, 36(8), 1089-1097. https://doi.org/10.1097/00004583-199708000-00016Sadeh, A., Hen-Gal, S., & Tikotzky, L. (2008). Young children's reactions to war-related stress: A survey and assessment of an innovative intervention. Pediatrics, 121(1), 46-53. https://doi.org/10.1542/peds.2007-1348Saigh, P. A., Yasik, A. E., Mitchell, P., & Abright, A. R. (2011). The psychological adjustment of a sample of New York City preschool children 8–10 months after September 11, 2001. Psychological Trauma: Theory, Research, Practice, and Policy, 3(2), 109-116. https://doi.org/10.1037/a0020701Schechter, D. S., Zygmunt, A., Coates, S. W., Davies, M., Trabka, K. A., McCaw, J., ... & Robinson, J. L. (2007). Caregiver traumatization adversely impacts young children's mental representations on the MacArthur Story Stem Battery. Attachment & Human Development, 9(3), 187-205. https://doi.org/10.1080/14616730701453762Schultz, D., Jaycox, L. H., Hickman, L. J., Setodji, C., Kofner, A., Harris, R., & Barnes, D. (2013). The relationship between protective factors and outcomes for children exposed to violence. Violence and victims, 28(4), 697-714. https://doi.org/10.1891/0886-6708.vv-d-12-00005Shehadeh, A., Loots, G., Vanderfaeillie, J., & Derluyn, I. (2015). The impact of parental detention on the psychological wellbeing of Palestinian children. PloS one, 10(7), e0133347. https://doi.org/10.1371/journal.pone.0133347Stuber, M. L., Nader, K., Yasuda, P., Pynoos, R. S., & Cohen, S. (1991). Stress responses after pediatric bone marrow transplantation: Preliminary results of a prospective longitudinal study. Journal of the American Academy of Child & Adolescent Psychiatry, 30(6), 952-957. https://doi.org/10.1097/00004583-199111000-00013Vasileva, M., Haag, A. C., Landolt, M. A., & Petermann, F. (2018). Posttraumatic Stress Disorder in Very Young Children: Diagnostic Agreement Between ICD‐11 and DSM‐5. Journal of traumatic stress, 31(4), 529-539. https://doi.org/10.1002/jts.22314Vasileva, M., & Petermann, F. (2017). Posttraumatic stress symptoms in preschool children in foster care: the influence of placement and foster family environment. Journal of traumatic stress, 30(5), 472-481. https://doi.org/10.1002/jts.22217Yagi, J., Fujiwara, T., Yambe, T., Okuyama, M., Kawachi, I., & Sakai, A. (2016). Does social capital reduce child behavior problems? Results from the Great East Japan Earthquake follow-up for Children Study. Social psychiatry and psychiatric epidemiology, 51(8), 1117-1123. https://doi.org/10.1007/s00127-016-1227-2

Non-standardised interviews (k=4)

Almqvist, K., & Brandell-Forsberg, M. (1997). Refugee children in Sweden: Post-traumatic stress disorder in Iranian preschool children exposed to organized violence. Child abuse & neglect, 21(4), 351-366. https://doi.org/10.1016/s0145-2134(96)00176-7Dawes, A., Tredoux, C., & Feinstein, A. (1989). Political violence in South Africa: Some effects on children of the violent destruction of their community. International journal of mental health, 18(2), 16-43. https://doi.org/10.1080/00207411.1989.11449122Feldman, R., & Vengrober, A. (2011). Posttraumatic stress disorder in infants and young children exposed to war-related trauma. Journal of the American Academy of Child & Adolescent Psychiatry, 50(7), 645-658. https://doi.org/10.1016/j.jaac.2011.03.001Halevi, G., Djalovski, A., Vengrober, A., & Feldman, R. (2016). Risk and resilience trajectories in war‐exposed children across the first decade of life. Journal of Child Psychology and Psychiatry, 57(10), 1183-1193. https://doi.org/10.1111/jcpp.12622

PTSD measure before 1 month (k=1)

Haag, A. C., & Landolt, M. A. (2017). Young children’s acute stress after a burn injury: Disentangling the role of injury severity and parental acute stress. Journal of pediatric psychology, 42(8), 861-870. https://doi.org/10.1093/jpepsy/jsx059

Tabled 1Table S1: Risk of bias assessment outcomes by criteria

Table S1: Risk of bias assessment outcomes by criteria