Caroline Cassels

May 26, 2011

May 26, 2010 (Honolulu, Hawaii) — Women soldiers may be at greater risk for combat stress than their male counterparts and much less likely to endorse proven protective factors for combat-related posttraumatic stress disorder (PTSD), new research suggests.

Results of a large study that anonymously surveyed a cohort of National Guard troops before and after deployment to Iraq suggest military women have more than twice the risk of developing combat-related PTSD than their male counterparts.

Furthermore, women were significantly less likely than men to feel prepared for combat or to endorse unit cohesion — 2 major factors shown to be protective against PTSD.

We found substantially higher rates of PTSD among women than men in this National Guard sample," principal investigator Anna Kline, PhD, told Medscape Medical News here at the American Psychiatric Association 2011 Annual Meeting, where the findings were presented.

"When we investigated the reasons for this we found men felt much more prepared for combat than women, and they were also much more likely to feel they had the support of their unit than women," added Dr. Kline, an investigator with the Department of Veterans Affairs–New Jersey Health Care System, East Orange.

'Unprecedented' Research Opportunity

General population studies have shown a higher prevalence of PTSD from all causes among women compared with men. There has been some previous research examining the impact of combat by sex in military populations. Dr. Kline noted the numbers of studies have been few and the results, with respect to the current conflicts, mixed.

Dr. Anna Kline

It has been difficult to investigate differences between the sexes in previous conflicts because the proportion of women in the military was so low. In Operation Iraqi Freedom and Operation Enduring Freedom, women represent approximately 14% of deployed forces, offering researchers an "unprecedented" opportunity for this type of research, said Dr. Kline.

She also noted that recent research suggests soldiers who feel well prepared for combat and have a strong sense of unit cohesion are less likely to develop PTSD.

To examine sex differences in risk and protective factors affecting the development of PTSD, the researchers conducted a longitudinal study in a cohort of 2665 members undergoing mandatory predeployment medical screening in 2008.

The investigators gathered self-administered survey data from participants before deployment to Iraq and again at integration events conducted approximately 3 months after deployment.

PTSD was measured using the National Center for PTSD Checklist. The investigators used a subscale of the Deployment Risk and Resiliency Inventory to measure unit cohesion and military preparedness. They also measured combat exposure and screened for predeployment PTSD.

Anonymity Key

A key feature of the study, said Dr. Kline, was that it was anonymous. "We know anonymity makes a huge difference in terms of the accuracy of the data, especially in the military when you are asking sensitive questions about mental health and substance use, so we developed an algorithm that allowed us to match (pre- and postdeployment) surveys without identifying individuals " she said.

The researchers successfully matched predeployment and postdeployment surveys from 922 National Guard members, including 91 women.

The results revealed that despite the fact that men and women had similar levels of combat exposure, they were significantly more likely to meet criteria for PTSD after deployment — 18.7% vs 8.7% (odds ratio [OR], 2.34; 95% confidence interval [CI], 1.27 – 4.32).

However, they were much less likely than men to report feeling well prepared for combat at baseline (14.3% vs 32.2%; P = .000) and more likely to report low unit cohesion during deployment (49.4% vs 30.9%; P = .002).

After adjusting for age, race, education, predeployment risk factors, combat exposure, and preexisting mental health conditions, women were still at significantly greater risk of developing PTSD.

However, when protective factors — perceived high unit cohesion and high military preparedness — were entered into the equation, the sex difference was no longer significant (adjusted OR, 1.68; 95% CI, 0.84 – 3.36).

According to Dr. Kline the study findings suggest a need to take a closer look at military training and possibly modify programs to ensure both women and men derive the protective effects of military preparedness and social support that comes with high unit cohesion.

"The military now has integrated gender-based basic training so men and women do prepare together. However, it is possible that even if they get exactly the same training, their perceptions [of training] could be very different. It is also possible that training is geared more towards the strengths of men, so they feel more prepared to handle the rigors of combat. These are areas that need further investigation," said Dr. Kline.

Sexual Abuse a Factor?

Dr. David Spiegel

Asked by Medscape Medical News to comment on the study, David Spiegel, MD, Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, California, said the doubling of PTSD risk among military women was "striking."

Even more impressive, he said, was the fact that the risk for PTSD "disappeared" after researchers controlled for unit cohesion and military preparedness.

"Frankly, the hidden factor, which I suspect may be most important, is that unfortunately there is a very high rate of sexual abuse of women in the military and that would have several effects. It would be a contributing factor, it would exacerbate any precombat-related trauma, and it would interfere with a woman's perception of unit cohesion.

"So it could be that unit cohesion may be code for respectful treatment of women. I'm sure there is variation of that between units where in some units mistreatment of women is not tolerated and others where people look the other way. I don't know for sure, but my suspicion is that this is a factor [in these results]," said Dr. Spiegel.

The findings further suggest that the "military needs to look harder at how they prepare women" and find ways of enhancing unit cohesiveness, he added.

The study was supported by the New Jersey Department of Military and Veterans Affairs. Dr. Kline and Dr. Spiegel have disclosed no relevant financial relationships.

American Psychiatric Association (APA) 2011 Annual Meeting: NR10-61. Presented May 17, 2011.


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