title: The prevalence of post-traumatic stress disorder (PTSD) in US combat soldiers: a head-to-head comparison of DSM-5 versus DSM-IV-TR symptom criteria with the PTSD checklist.
abstract: BACKGROUND
  The definition of post-traumatic stress disorder (PTSD) underwent substantial changes in the 2013 edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5). How this will affect estimates of prevalence, whether clinical utility has been improved, and how many individuals who meet symptom criteria according to the previous definition will not meet new criteria is unknown. Updated screening instruments, including the PTSD checklist (PCL), have not been compared with previously validated methods through head-to-head comparisons.
  
  
  METHODS
  We compared the new 20-item PCL, mapped to DSM-5 (PCL-5), with the original validated 17-item specific stressor version (PCL-S) in 1822 US infantry soldiers, including 946 soldiers who had been deployed to Iraq or Afghanistan. Surveys were administered in November, 2013. Soldiers alternately received either of two surveys that were identical except for the order of the two PCL versions (911 per group). Standardised scales measured major depression, generalised anxiety, alcohol misuse, and functional impairment.
  
  
  RESULTS
  In analysis of all soldiers, 224 (13%) screened positive for PTSD by DSM-IV-TR criteria and 216 (12%) screened positive by DSM-5 criteria (κ 0·67). In soldiers exposed to combat, 177 (19%) screened positive by DSM-IV-TR and 165 (18%) screened positive by DSM-5 criteria (0·66). However, of 221 soldiers with complete data who met DSM-IV-TR criteria, 67 (30%) did not meet DSM-5 criteria, and 59 additional soldiers met only DSM-5 criteria. PCL-5 scores from 15-38 performed similarly to PCL-S scores of 30-50; a PCL-5 score of 38 gave optimum agreement with a PCL-S of 50. The two definitions showed nearly identical association with other psychiatric disorders and functional impairment.
  
  
  CONCLUSIONS
  Our findings showed the PCL-5 to be equivalent to the validated PCL-S. However, the new PTSD symptom criteria do not seem to have greater clinical utility, and a high percentage of soldiers who met criteria by one definition did not meet the other criteria. Clinicians need to consider how to manage discordant outcomes, particularly for service members and veterans with PTSD who no longer meet criteria under DSM-5.
  
  
  BACKGROUND
  US Army Military Operational Medicine Research Program (MOMRP), Fort Detrick, MD.
authors.affiliation: Center for Psychiatry and Neuroscience, Walter Reed Army Institute of Research, Silver Spring, MD, USA. Electronic address: charles.hoge@us.army.mil.
authors.forename: Charles W
authors.initials: CW
authors.lastname: Hoge
authors.affiliation: Center for Psychiatry and Neuroscience, Walter Reed Army Institute of Research, Silver Spring, MD, USA.
authors.forename: Lyndon A
authors.initials: LA
authors.lastname: Riviere
authors.affiliation: Center for Psychiatry and Neuroscience, Walter Reed Army Institute of Research, Silver Spring, MD, USA.
authors.forename: Joshua E
authors.initials: JE
authors.lastname: Wilk
authors.affiliation: Center for Psychiatry and Neuroscience, Walter Reed Army Institute of Research, Silver Spring, MD, USA.
authors.forename: Richard K
authors.initials: RK
authors.lastname: Herrell
authors.affiliation: Department of Psychology, Auburn University, AL, USA.
authors.forename: Frank W
authors.initials: FW
authors.lastname: Weathers