LeardMann et al. BMC Public Health 2010, 10:437 http://www.biomedcentral.com/1471-2458/10/437 Page 6 of 8 Table 4 Adjusted risk of posttraumatic stress disorder and mental health disorders among deployed male Marines by adverse childhood experiences PTSDa Mental Health Disorders not Specific to PTSDb Adverse Childhood Experiences History of ACEd in multiple categories None ACE in 1 category ACE in 2 or more categories Prevalence per 100 2.47 2.86 3.81 HR (95% CI) 1.00 1.21 (0.87, 1.69) 1.57 (1.09, 2.26) Prevalence per 100 6.03 6.90 8.57 HR (95% CI) 1.00 1.17 (0.94, 1.45) 1.41 (1.10, 1.80) Abbreviations: ACE = adverse childhood experiences; AFQT = Armed Forces Qualification Test; CI = confidence interval; HR = hazard ratio; PTSD = posttraumatic stress disorder. aModels the risk of having a PTSD diagnosis after returning from first deployment in support of the operations in Iraq and Afghanistan and within 2 years of last deployment, after adjusting for AFQT score, number of deployments, mental health diagnosis prior to deployment, and marital status. bModels the risk of a mental health diagnosis after returning from first deployment in support of the operations in Iraq and Afghanistan and within 2 years of last deployment, after adjusting for AFQT score, smoking status, race/ethnicity, and marital status. Cohort identified the risk of post-combat PTSD as increased at least two-fold among a diverse group of military members, men and women, who survived prior adult trauma without evidence of PTSD, but subse- quently deployed to a combat environment [35]. In a meta-analysis [8] of childhood adversity, younger age at time of exposure, less education, minority race/ ethnicity, trauma severity, and lack of social support among veterans were identified as risk factors for devel- oping PTSD. Consistent with previous research [36,37], men in this study who scored in the lowest quartile on an intelligence test (as measured by the AFQT) had an increased risk of being diagnosed with postdeployment PTSD. The findings of this study indicate that Marines with more than 1 military deployment were at increased risk for PTSD compared with their peers with only 1 deployment. While combat trauma data were not col- lected for this study, number of deployments may be related to trauma severity. In contrast to previous stu- dies, younger age, less education, and minority race/eth- nicity were not significantly associated with an increased risk for PTSD in this study [8]. The limited range in age and education among this study population may explain the lack of association with PTSD. Also in contrast to previous studies indicating lack of social support as a risk factor for PTSD [11,18,38,39], Marines in this study who were married at the time of deployment had a higher risk of being diagnosed with PTSD. It is possible that elevated rates of PTSD among married men are a result of spousal encouragement to seek medical care, and consequently be diagnosed with PTSD. And while the current study found the number of friends during recruit training not significantly associated with PTSD, it is reasonable that the number of friends recruits have in training may be different by the time they deploy. Unlike many recent studies that have used self- reported screening tools for PTSD outcomes [17,18], this study used a standard diagnosis in electronic medi- cal records to identify men with PTSD. Using outpatient and hospitalization records, 2.7% of Marines were diag- nosed with postdeployment PTSD within 2 years follow- ing deployment. Previous studies using interviews and screening criteria indicate that PTSD among Marines and Army soldiers returning from the conflicts in Iraq and Afghanistan is as high as 4.7% to 19.9% [9,10]. Ser- vice members who screen positive for PTSD, however, may not subsequently be diagnosed with PTSD. Pre- vious research suggests service members diagnosed with PTSD may represent a small subset of those who screen positive for PTSD using self-reported assessment tools. Hoge et al. [10] found that only 23% to 40% of service members who screened positive for a mental health dis- order reported seeking mental health care. Negative stigma, a belief that seeking mental health care could harm one’s career, and other barriers have been sug- gested as reasons that service members resist seeking mental health care [10]. Of those service members who accessed mental health services, approximately one third received a mental health diagnosis [9]. Therefore, men diagnosed with PTSD in this study may have been more willing to seek mental health care than their peers. Comparatively, it is possible that those willing to report ACE are also more likely to seek medical attention. As suggested, negative stigma may be one reason that ser- vice members do not seek mental healthcare and theo- retically could also be a reason that the same service members are hesitant to report ACE. Strengths and limitations This study has some limitations that should be consid- ered. A study period of only 2 years may not be long enough to adequately capture all members who may be diagnosed with PTSD; although the onset of PTSD symptoms usually occurs within 3 months after a trau- matic event [40]. Previous studies have identified com- bat exposures as one of the most consistent risk factors for developing combat-related PTSD [5,7,10,41]. While cumulative length of deployment was used as a covariate