Where You Are Sent and for How Long Influences Post-Traumatic Stress Disorder

Recent research suggests that the wars in Afghanistan and Iraq, also known as Operation Enduring Freedom (OEF) and Operation Iraqi Freedom (OIF), pose substantial mental health challenges to U.S. military service members and the mental health systems that serve them. Estimates of military service related post-traumatic stress disorder (PTSD) vary widely, from 4 percent to 45 percent depending on the samples and how PTSD was measured. PTSD is associated with a host of long-term family and workplace problems and often goes along with other psychiatric and physical disorders.

In The Effect of OEF/OIF Deployment Intensity on the Rate of Posttraumatic Stress Disorder Among Active Duty Population (NBER Working Paper No. 15203), authors Yu-Chu Shen, Jeremy Arkes, Boon Wah Kwan, Lai Yee Tan, and Thomas Williams estimate what the rates of PTSD are for various service groups and deployment experiences. The researchers use a random sample based on all active duty enlisted personnel serving anywhere in the world between 2001 and 2006, and examine the four services (Army, Marines, Navy, and Air Force) individually. They find that the percentage of PTSD diagnoses among the active duty population varies by service. This percentage is less than 1 percent in all four services for those who are not deployed on OEF/OIF missions. Those deployed to Iraq/Afghanistan have a much higher probability of developing PTSD -- from 1.3 percent for the Air Force to 6.5 percent for the Navy. Controlling for relevant background characteristics, the researchers find that deployment to Iraq/Afghanistan increases the odds of developing PTSD substantially, with the odds ratio ranging from 1.25 for the Air Force to 9.06 for the Navy. Tour length also appears to matter: a deployment lasting longer than 180 days as compared to a short tour increases the odds of PTSD by 1.11 times to 2.84 times, depending on the service. For both the Army and the Navy, a deployment to Iraq/Afghanistan further exacerbates the adverse effect of tour length.

The Department of Defense has been addressing PTSD. It introduced the Post-Deployment Health Reassessment (PDHRA) in March 2005, and it mandates the completion of this re-assessment at 90-180 days after a deployment. However, the authors' data show that almost 75 percent of the PTSD population in their sample was not diagnosed with PTSD until 200 days after their last deployment. The average lapse between the last deployment and the first diagnosis of PTSD was 291 days.

-- Lester Picker