The study results show that those who separated from military service were at increased risk of suicide compared with personnel who had not separated.
The authors of the new study write that the US military has traditionally had lower rates of suicide compared with the general population. However, suicide rates among active duty personnel have risen sharply in the last decade - almost doubling among the Army and Marines Corps.
Despite speculation that there may be a link between deployment and increased incidence of suicide, data from the Department of Defense (DoD) show there was no history of deployment in about half of suicide cases that occurred on active duty.
However, the authors of the new study point out that the DoD data do not track mortality of service members after they leave the army. And as personnel who screen positively for mental health problems following deployment are more likely to leave military service, the authors say it is important to account for suicides that occur after personnel separate from service.
To address these methodological limitations in previous research, the authors of the new study examined the association between deployment and suicide among all 3.9 million personnel who served in the US military during Operation Enduring Freedom - the Afghanistan-centered military campaign that took place between October 7th, 2001 and December 31st, 2007.
In what they claim is the most comprehensive study to examine suicide risk in relation to these deployments, the researchers examined data on suicide mortality during the period October 7th, 2001 to December 31st, 2009.
No association between deployment and increased suicide risk
The authors identified 5,041 suicides among the 31,962 deaths of military personnel during the study period. Of these suicides, 1,162 were among service members who deployed and 3,879 were among service members who did not deploy - a rate of 18.86 and 17.78 per 100,000 person-years, respectively.
However, the results show that those who separated from military service were at increased risk of suicide, compared with personnel who had not separated. Among personnel who had separated, those who had deployed and those who had not deployed were at comparable - if elevated - risks for suicide.
Individuals who separated from the military with less than 4 years of service were more at risk of suicide than those who separated following 4 or more years of military service. For personnel who had 20 or more years of service when they left the military, the suicide rate was 11.01 per 100,000 person-years. In comparison, the suicide rate among individuals who served less than a year was 48.04 per 100,000 person-years.
Transition to military life, loss of a shared military identity and difficulty finding work were all considered by the researchers as possible explanations for why suicide rates were so elevated among personnel who had served only a short time.
Alternatively, the authors suggest, it is possible that the factors that contributed to early military discharge in these individuals - such as legal problems, mental health disorders, medical problems, disciplinary issues and disability - may have also contributed to their decisions to commit suicide.
This was a very large study, taking into account all US military personnel that served in the Operation Enduring Freedom and Operation Iraqi Freedom campaigns. The authors suggest, however, that some suicides may have been misclassified or underestimated, as suicidal service members may have intentionally placed themselves in harm's way.
The authors conclude:
"In summary, the accelerated rate of suicide among members of the US Armed Forces and veterans in recent years is concerning. Although there has been speculation that deployment to the [Operation Enduring Freedom and Operation Iraqi Freedom] combat theaters may be associated with military suicides, the results of this research do not support that hypothesis.
Future research is needed to examine combat injuries, mental health and other factors that may increase suicide risk. It is possible that such factors alone and in combination with deployment increase suicide risk."