title: How to quantify exposure to traumatic stress? Reliability and predictive validity of measures for cumulative trauma exposure in a post-conflict population.
abstract: BACKGROUND
  While studies with survivors of single traumatic experiences highlight individual response variation following trauma, research from conflict regions shows that almost everyone develops posttraumatic stress disorder (PTSD) if trauma exposure reaches extreme levels. Therefore, evaluating the effects of cumulative trauma exposure is of utmost importance in studies investigating risk factors for PTSD. Yet, little research has been devoted to evaluate how this important environmental risk factor can be best quantified.
  
  
  METHODS
  We investigated the retest reliability and predictive validity of different trauma measures in a sample of 227 Ugandan rebel war survivors. Trauma exposure was modeled as the number of traumatic event types experienced or as a score considering traumatic event frequencies. In addition, we investigated whether age at trauma exposure can be reliably measured and improves PTSD risk prediction.
  
  
  RESULTS
  All trauma measures showed good reliability. While prediction of lifetime PTSD was most accurate from the number of different traumatic event types experienced, inclusion of event frequencies slightly improved the prediction of current PTSD.
  
  
  CONCLUSIONS
  As assessing the number of traumatic events experienced is the least stressful and time-consuming assessment and leads to the best prediction of lifetime PTSD, we recommend this measure for research on PTSD etiology.
authors.affiliation: Clinical & Biological Psychology, Institute of Psychology and Education, Ulm University, Ulm, Germany.|Vivo International, Allensbach, Germany; sarah.wilker@uni-ulm.de.
authors.forename: Sarah
authors.initials: S
authors.lastname: Wilker
authors.affiliation: Vivo International, Allensbach, Germany.|Clinical Psychology, University of Konstanz, Konstanz, Germany.
authors.forename: Anett
authors.initials: A
authors.lastname: Pfeiffer
authors.affiliation: SAP Switzerland AG, Tägerwilen, Switzerland.
authors.forename: Stephan
authors.initials: S
authors.lastname: Kolassa
authors.affiliation: Clinical & Biological Psychology, Institute of Psychology and Education, Ulm University, Ulm, Germany.
authors.forename: Daniela
authors.initials: D
authors.lastname: Koslowski
authors.affiliation: Vivo International, Allensbach, Germany.|Clinical Psychology, University of Konstanz, Konstanz, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Elbert
authors.affiliation: Clinical & Biological Psychology, Institute of Psychology and Education, Ulm University, Ulm, Germany.
authors.forename: Iris-Tatjana
authors.initials: IT
authors.lastname: Kolassa
keywords: Cumulative trauma exposure; event list; posttraumatic stress disorder; predictive validity; reliability