Research

New onset and persistent symptoms of post-traumatic stress disorder self reported after deployment and combat exposures: prospective population based US military cohort study

BMJ 2008; 336 doi: http://dx.doi.org/10.1136/bmj.39430.638241.AE (Published 14 February 2008) Cite this as: BMJ 2008;336:366
  1. Tyler C Smith, director 12,
  2. Margaret A K Ryan, associate adjunct professor12,
  3. Deborah L Wingard, professor and associate chief2,
  4. Donald J Slymen, professor 3,
  5. James F Sallis, professor 4,
  6. Donna Kritz-Silverstein, professor 5
  7. for the Millennium Cohort Study Team
  1. 1Department of Defense Center for Deployment Health Research at the Naval Health Research Center, San Diego, CA 92106, USA
  2. 2Division of Epidemiology, Department of Family and Preventive Medicine, University of California San Diego, La Jolla, CA 92093-0607
  3. 3Graduate School of Public Health, San Diego State University, San Diego, CA 92108
  4. 4Department of Psychology, San Diego State University, San Diego, CA 92108
  5. 5Division of Epidemiology, Department of Family and Preventive Medicine, University of California San Diego, La Jolla, CA 92093-0631
  1. Correspondence to: T C Smith tyler.c.smith{at}med.navy.mil
  • Accepted 25 November 2007

Abstract

Objective To describe new onset and persistence of self reported post-traumatic stress disorder symptoms in a large population based military cohort, many of whom were deployed in support of the wars in Iraq and Afghanistan.

Design Prospective cohort analysis.

Setting and participants Survey enrolment data from the millennium cohort (July 2001 to June 2003) obtained before the wars in Iraq and Afghanistan. Follow-up (June 2004 to February 2006) data on health outcomes collected from 50 184 participants.

Main outcome measures Self reported post-traumatic stress disorder as measured by the posttraumatic stress disorder checklist—civilian version using Diagnostic and Statistical Manual of Mental Disorders, fourth edition criteria.

Results More than 40% of the cohort were deployed between 2001 and 2006; between baseline and follow-up, 24% deployed for the first time in support of the wars in Iraq and Afghanistan. New incidence rates of 10-13 cases of post-traumatic stress disorder per 1000 person years occurred in the millennium cohort. New onset self reported post-traumatic stress disorder symptoms or diagnosis were identified in 7.6-8.7% of deployers who reported combat exposures, 1.4-2.1% of deployers who did not report combat exposures, and 2.3-3.0% of non-deployers. Among those with self reported symptoms of post-traumatic stress disorder at baseline, deployment did not affect persistence of symptoms.

Conclusions After adjustment for baseline characteristics, these prospective data indicate a threefold increase in new onset self reported post-traumatic stress disorder symptoms or diagnosis among deployed military personnel who reported combat exposures. The findings define the importance of post-traumatic stress disorder in this population and emphasise that specific combat exposures, rather than deployment itself, significantly affect the onset of symptoms of post-traumatic stress disorder after deployment.

Footnotes

  • We are indebted to all millennium cohort study participants. We thank Scott L Seggerman and Greg D Boyd from the Management Information Division, Defense Manpower Data Center, Seaside, CA. We also thank Lacy Farnell, Isabel Jacobson, Cynthia Leard, Travis Leleu, Robert Reed, Steven Spiegel, Kari Welch, and James Whitmer from the Department of Defense Center for Deployment Health Research; Michelle Stoia, from the Naval Health Research Center, San Diego, CA; and Karl E Friedl and professionals at the US Army Medical Research and Material Command, especially those from the Military Operational Medicine Research Program, Fort Detrick, MD. We appreciate the support of the Henry M Jackson Foundation for the Advancement of Military Medicine, Rockville, MD.

  • In addition to the authors, the Millennium Cohort Study Team includes Paul J Amoroso, Madigan Army Medical Center, Tacoma, WA; Edward J Boyko, Seattle Epidemiologic Research and Information Center, Department of Veterans Affairs Puget Sound Health Care System, Seattle, WA; Gary D Gackstetter and Tomoko I Hooper, Department of Preventive Medicine and Biometrics, Uniformed Services University of the Health Sciences, Bethesda, MD; Gregory C Gray, College of Public Health, University of Iowa, Iowa City, IA; James R Riddle and Timothy S Wells, Air Force Research Laboratory, Wright-Patterson Air Force Base, OH; and Besa Smith, Department of Defense Center for Deployment Health Research at the Naval Health Research Center, San Diego, CA.

  • Contributors: TCS, MAKR, DLW, DJS, JFS, and DKS were involved in study design and concept. TCS and MAKR were involved in acquisition of data. TCS, MAKR, DLW, DJS, JFS, and DKS were responsible for analysis and interpretation of data. TCS, MAKR, DLW, DJS, JFS, and DKS drafted the manuscript. TCS, MAKR, DLW, DJS, JFS, and DKS did the statistical analysis. TCS, MAKR, DLW, DJS, JFS, and DKS critically revised the manuscript and approved the final version. TCS is the guarantor.

  • Funding: This represents Naval Health Research Center report 07-09, supported by the Department of Defense, under work unit No 60002. Funding sources did not play any other role. The views expressed in this article are those of the authors and do not reflect the official policy or position of the US Department of the Navy; US Department of the Army; US Department of the Air Force; US Department of Defense; US Department of Veterans Affairs; US Government; University of California, San Diego; or San Diego State University.

  • Competing interests: None declared.

  • Ethical approval: This research has been conducted in compliance with all applicable federal regulations governing the protection of human subjects in research (Protocol NHRC.2000.007).

  • Provenance and peer review: Not commissioned; externally peer reviewed.

  • Accepted 25 November 2007
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